Page 1
Expi293™ Expression System: Structural
Biology and Inducible Expression Modules
USER GUIDE
For scalable transfection of Expi293F™ GnTI- and Expi293F™ Inducible cell lines in
a chemically defined, serum-free medium, using the ExpiFectamine™ 293
Transfection Kit.
For scalable metabolic protein labeling using Expi293F™ cell lines in a chemically
defined, serum-free, methionine-free medium using a methionine-deficient
ExpiFectamine™ 293 Transfection Kit.
Catalog Numbers A39250, A39250CN, A39251, A14527CN, A39252, A41276CN, A41249, A14524,
A14525, A14526, A39249
Publication Number MAN0007814
Revision B.0
For Research Use Only. Not for use in diagnostic procedures.
Page 2
Life Technologies Corporation | 5781 Van Allen Way | Carlsbad, CA 92008
For descriptions of symbols on product labels or product documents, go to thermofisher.com/symbols-definition.
The information in this guide is subject to change without notice.
DISCLAIMER: T
O THE EXTENT ALLOWED BY LAW, THERMO FISHER SCIENTIFIC INC. AND/OR ITS AFFILIATE(S) WILL NOT BE
LIABLE FOR SPECIAL, INCIDENTAL, INDIRECT, PUNITIVE, MULTIPLE, OR CONSEQUENTIAL DAMAGES IN CONNECTION WITH OR
ARISING FROM THIS DOCUMENT, INCLUDING YOUR USE OF IT.
Revision history: Pub. No. MAN0007814
Revision Date Description
B.0 29
A.0 14 April 2019 Update of user guide to bring it up to current standards and styles.
2.0 11 June 2018 Format conversion. Addition of application notes.
1.0 June 2013 Introduction of new format
— 2012 New document
May 2020
Update to reflect inducible expression and structural biology kit
configurations.
Addition of GNTI cells, Inducible cells, and Inducible GNTI cells.
Updating of protocols to incorporate the new cell lines added.
Important Licensing Information: This pr
oduct may be covered by one or more Limited Use Label Licenses. By use of this product,
you accept the terms and conditions of all applicable Limited Use Label Licenses.
TRADEMARKS: All trademarks are the property of Thermo Fisher Scientific and its subsidiaries unless otherwise specified.
©2020 Thermo Fisher Scientific Inc. All rights reserved.
Page 3
Contents
■
CHAPTER 1 Product information .................................................. 6
Product description ............................................................. 6
Contents and storage ............................................................ 7
Components of the Expi293™ Expression System: structural biology and
inducible expression modules ................................................. 10
Expi293F™ Cells ........................................................... 10
Expi293F™ GnTI- Cells ..................................................... 10
Expi293F™ Inducible Cells .................................................. 10
Expi293F™ Inducible GnTI- Cells ............................................. 10
Expi293™ Expression Medium ............................................... 11
Expi293™ Met (-) Expression Medium ........................................ 11
ExpiFectamine™ 293 Reagent ............................................... 12
ExpiFectamine™ 293 Transfection Enhancer 1 ................................. 12
ExpiFectamine™ 293 Transfection Enhancer 2 ................................. 12
ExpiFectamine™ 293 Met (-) Transfection Enhancer 2 .......................... 12
Opti-Plex™ Complexation Buer ............................................ 13
pRABBIT IgG IRES-EmGFP Positive Control Vector ............................ 13
pcDNA™5/TO Mammalian Expression Vector .................................. 13
PNGase F Glycan Cleavage Kit .............................................. 13
■
Expi293
CHAPTER 2 Methods ............................................................. 14
Procedural guidelines for Expi293F™ cell culture ................................... 14
General cell handling ....................................................... 14
Guidelines for thawing and storing cells ...................................... 14
Guidelines for cell maintenance and subculturing .............................. 14
Guidelines for inducible cells ................................................ 15
Guidelines for media ....................................................... 16
Thaw and establish Expi293F™ cell lines .......................................... 16
Required materials ......................................................... 16
Thaw Expi293F™ cells ...................................................... 16
Subculture Expi293F™ cell lines ................................................. 17
Required materials ......................................................... 17
Subculture Expi293F™ cells ................................................. 18
Cryopreserve Expi293F™ cells ............................................... 19
™
Expression System User Guide
3
Page 4
Contents
Transfect Expi293F™ cell lines using ExpiFectamine™ 293 Transfection Kit ............. 19
Required materials ......................................................... 20
Guidelines for transfection .................................................. 20
Day −2: Subculture cells ................................................... 21
Day −1: Seed cells ........................................................ 21
Day 0: Transfect cells ...................................................... 21
Day +1: Add Enhancers .................................................... 22
Day +5: Harvest protein .................................................... 22
Transfect Expi293F™ cell lines using ExpiFectamine™ 293 Met (-) Transfection Kit
for metabolic protein labeling .................................................. 22
Required materials ......................................................... 23
Guidelines for transfection .................................................. 23
Day −2: Subculture cells ................................................... 23
Day −1: Seed cells ........................................................ 24
Day 0: Perform metabolic labeling ........................................... 24
Day 0: Transfect cells ...................................................... 25
Day +1: Add Enhancers .................................................... 25
Day +5: Harvest protein .................................................... 26
■
APPENDIX A Additional guidelines .............................................. 27
Guidelines to optimize protein expression ......................................... 27
Equipment .................................................................... 27
Cells ......................................................................... 28
Plasmid DNA complexation ..................................................... 28
Harvest ....................................................................... 28
Cell culture supernatant clarification .............................................. 29
■
APPENDIX B Positive control for transfection and expression ................ 30
pRABBIT IgG IRES-EmGFP Positive Control Vector ................................ 30
Transfection and expression ..................................................... 30
■
APPENDIX C Scaling up transfections .......................................... 31
Scale up transfections .......................................................... 31
■
APPENDIX D Ordering information .............................................. 33
Additional products ............................................................ 33
Shaker flasks for suspension culture .............................................. 34
Plasmid purification products .................................................... 34
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Expi293™ Expression System User Guide
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APPENDIX E Safety ............................................................... 35
Chemical safety ................................................................ 36
Biological hazard safety ......................................................... 37
■
APPENDIX F Documentation and support ...................................... 38
Customer and technical support ................................................. 38
Limited product warranty ........................................................ 38
Contents
Expi293™ Expression System User Guide
5
Page 6
1
IMPORTANT! Before using this product, read and understand the information in the
“Safety” appendix in this document.
Product description
The Gibco™ Expi293™ Expression System is a high-yield transient expression system
based on suspension-adapted Human Embryonic Kidney (HEK) cells. As part of the
structural biology and inducible expression modules, we oer 3 System Starter Kits
for structural biology or inducible expression and additional reagents to allow
metabolic labelling of proteins. Each Expi293™ Expression System Starter Kit
provides cells, culture medium, and reagents to express a total of 1 liter production
volume.
The structural biology and inducible expression modules of the Expi293™ Expression
System includes four Expi293F™ cell lines that can be used to express your protein of
interest.
•
Use Expi293F™ cells for metabolic protein labeling.
•
Use Expi293F™ GnTI- Cells for expression of proteins with a uniform
glycosylation pattern.
•
Use Expi293F™ Inducible Cells for regulated expression of proteins through
tetracycline mediated induction.
•
Use Expi293F™ Inducible GnTI- Cells for regulated expression of proteins with a
uniform glycosylation pattern.
Product information
Each of these cell lines display the same growth kinetics, follow the same
transfection protocols, and can be used in metabolic protein labeling studies.
For metabolic (methionine) protein labeling, Expi293™ Met (-) Expression Medium and
the ExpiFectamine™ 293 Met (-) Transfection Kit should be used to metabolically label
proteins of interest with L-Methionine (Methyl-13C) or L-Selenomethionine.
Expi293™ Met (-) Expression Medium and the ExpiFectamine™ 293 Met (-)
Transfection Kit can be ordered separately or together as part of the Expi293™ Met (-)
Protein Labeling Kit. L-Methionine (Methyl-13C) and L-Selenomethionine can be
ordered separately.
For further instruction on metabolically labeling proteins using the Expi293
Expression System, see “Transfect Expi293F™ cell lines using ExpiFectamine™ 293
Met (-) Transfection Kit for metabolic protein labeling” on page 22.
6
Expi293™ Expression System User Guide
™
Page 7
Chapter 1
Contents and storage
Table 1 Expi293™ GnTI- Expression System Kit (Cat. No. A39250 or A39250CN)
Contents Amount Cat. No. Storage
Product information
Contents and storage
1
Expi293F™ GnTI- Cells
[1]
(1 × 107 cells/mL) 1 mL A39240 Liquid nitrogen
Expi293™ Expression Medium 1 L A1435101
ExpiFectamine™ 293 Transfection Kit:
•
ExpiFectamine™ 293 Reagent
•
ExpiFectamine™ 293 Transfection Enhancer 1
•
ExpiFectamine™ 293 Transfection Enhancer 2
1 kit for 1 L of
culture
A14524
2°C to 8°C
Protect from light
Opti-Plex™ Complexation Buer 100 mL A4096801
pRABBIT IgG IRES-EmGFP Positive Control Vector (at
1 mg/mL in TE
[3]
Buer, pH 8.0)
150 µg A39243 −20°C
PNGase F Glycan Cleavage Kit 1 Kit A39245 −20°C
[1]
Cells are cryopreserved in 90% Expi293™ Expression Medium and 10% DMSO.
[2]
Store the frozen cells in liquid nitrogen immediately upon receipt and until ready to use. Do not store the cells at −80°C.
[3]
TE buffer, pH 8.0: 10 mM Tris-HCl, 1 mM EDTA, pH 8.0.
Table 2 Expi293™ Inducible Expression System Kit (Cat. No. A39251 or A14527CN)
Expi293F™ Inducible Cells
Contents
[1]
(1 × 107 cells/mL) 1 mL A39241 Liquid nitrogen
Amount Cat. No. Storage
[2]
[2]
Expi293™ Expression Medium 1 L A1435101
ExpiFectamine™ 293 Transfection Kit:
•
ExpiFectamine™ 293 Reagent
•
ExpiFectamine™ 293 Transfection Enhancer 1
•
ExpiFectamine™ 293 Transfection Enhancer 2
1 kit for 1 L of
culture
A14524
Opti-Plex™ Complexation Buer 100 mL A4096801
pRABBIT IgG IRES-EmGFP Positive Control Vector (at
1 mg/mL in TE
[3]
Buer, pH 8.0)
150 µg A39243
pcDNA™5/TO Mammalian Expression Vector 20 µg V103320
Tetracycline Hydrochloride
[1]
Cells are cryopreserved in 90% Expi293™ Expression Medium and 10% DMSO.
[2]
Store the frozen cells in liquid nitrogen immediately upon receipt and until ready to use. Do not store the cells at −80°C.
[3]
TE buffer, pH 8.0: 10 mM Tris-HCl, 1 mM EDTA, pH 8.0.
[4]
Not included in Cat. No. A41275.
[4]
500 mg A39246 Protect from light
2°C to 8°C
Protect from light
−20°C
and moisture
Room temperature
Expi293™ Expression System User Guide
7
Page 8
Chapter 1 Product information
1
Contents and storage
Table 3 Expi293™ Inducible GnTI- Expression System Kit (Cat. No. A39252 or A41276CN)
Contents Amount Cat. No. Storage
Expi293F™ Inducible GnTI- Cells
[1]
(1 × 107 cells/mL) 1 mL A39242 Liquid nitrogen
Expi293™ Expression Medium 1 L A1435101
ExpiFectamine™ 293 Transfection Kit:
•
ExpiFectamine™ 293 Reagent
•
ExpiFectamine™ 293 Transfection Enhancer 1
•
ExpiFectamine™ 293 Transfection Enhancer 2
1 kit for 1 L of
culture
A14524
2°C to 8°C
Protect from light
Opti-Plex™ Complexation Buer 100 mL A4096801
pRABBIT IgG IRES-EmGFP Positive Control Vector (at
1 mg/mL in TE
[3]
Buer, pH 8.0)
150 µg A39243
−20°C
pcDNA™5/TO Mammalian Expression Vector 20 µg V103320
Tetracycline Hydrochloride
[4]
500 mg A39246 Protect from light
and moisture
Room temperature
PNGase F Glycan Cleavage Kit 1 kit A39245 −20°C
[1]
Cells are cryopreserved in 90% Expi293™ Expression Medium and 10% DMSO.
[2]
Store the frozen cells in liquid nitrogen immediately upon receipt and until ready to use. Do not store the cells at −80°C.
[3]
TE buffer, pH 8.0: 10 mM Tris-HCl, 1 mM EDTA, pH 8.0.
[4]
Not included in Cat. No. A41276.
[2]
Table 4 Expi293™ Met (-) Protein Labeling Kit (Cat. No. A41249)
Contents
ExpiFectamine™ 293 Met (-) Transfection Kit
•
ExpiFectamine™ 293 Reagent
•
ExpiFectamine™ 293 Transfection Enhancer 1
•
ExpiFectamine™ 293 Met (-) Transfection Enhancer 2
•
Opti-Plex™ Complexation Buer
Amount Cat. No. Storage
1 kit for 1 L
A39249
culture
Expi293™ Met (-) Expression Medium 1 L A4096701
2°C to 8°C
Protect from light.
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Expi293™ Expression System User Guide
Page 9
Chapter 1 Product information
Table 5 ExpiFectamine™ 293 Transfection Kit (Cat. No. A14524, A14525, and A14526)
Contents Amount Cat. No. Storage
ExpiFectamine™ 293 Transfection Kit:
Contents and storage
1
•
ExpiFectamine™ 293 Reagent
•
ExpiFectamine™ 293 Transfection Enhancer 1
•
ExpiFectamine™ 293 Transfection Enhancer 2
•
1 kit for 1 L
of culture
•
1 kit for 10 L
of culture
•
1 kit for 50 L
of culture
Table 6 ExpiFectamine™ 293 Met (-) Transfection Kit (Cat. No. A39249)
Contents Amount Cat. No. Storage
ExpiFectamine™ 293 Met (-) Transfection Kit
•
ExpiFectamine™ 293 Reagent
•
ExpiFectamine™ 293 Transfection Enhancer 1
•
ExpiFectamine™ 293 Met (-) Transfection Enhancer 2
•
Opti-Plex™ Complexation Buer
1 kit for 1 L
culture
•
A14524
•
A14525
•
A14526
A39249
2°C to 8°C
Protect from light.
2°C to 8°C
Protect from light.
Expi293™ Expression System User Guide
9
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Chapter 1
1
Components of the Expi293™ Expression System: structural biology and inducible expression modules
Product information
Components of the Expi293™ Expression System: structural
biology and inducible expression modules
The Expi293™ Expression System is based on high density culture of Expi293F™ Cells
in Expi293™ Expression Medium. Transient expression is by the cationic lipid-based
ExpiFectamine™ 293 Reagent with specialized transfection enhancers. The
components work together to generate 2- to 10-fold higher protein yields than
previous generation transient expression systems.
Expi293F™ Cells
Expi293F™ Cells are human cells derived from the 293F cell line, and are a core
component of the Expi293™ Expression System. They are maintained in suspension
culture and will grow to high density in Expi293™ Expression Medium. Expi293F
Cells are highly transfectable and generate superior protein yields compared to
standard 293 cell lines in transient protein expression.
Expi293F™ GnTI- Cells
™
Expi293F™ GnTI- Cells are derived from Expi293F™ Cells and have been engineered
to lack N-acetylglucosaminyl-transferase I (GnTI) enzyme activity leading to the
production of glycoproteins with a uniform (GlcNAc)2Man5 glycopattern.
Expi293F™ Inducible Cells
Expi293F™ Inducible Cells are derived from Expi293F™ Cells and stably express high
levels of the tetracycline repressor protein (TetR) from the pcDNA™6/TR plasmid.
When used with compatible inducible vectors (e.g. pcDNA™5/TO Mammalian
Expression Vector), the gene of interest is repressed with very low levels of basal
expression until induction with tetracycline. Expression can be modulated by addition
of dierent amounts of tetracycline. For best results, Expi293F™ Inducible Cells
should be maintained under selective pressure of blasticidin. For further details, see
“Guidelines for inducible cells” on page 15.
Expi293F™ Inducible GnTI- Cells
Expi293F™ Inducible GnTI- Cells are derived from Expi293F™ GnTI- Cells and stably
express high levels of the tetracycline repressor protein (TetR) from the pcDNA™6/TR
plasmid in combination with knockout of the GnTI gene. When used with compatible
inducible vectors (e.g. pcDNA™5/TO Mammalian Expression Vector), the gene of
interest is repressed with very low levels of basal expression until induction with
tetracycline. Expression can be modulated by addition of dierent amounts of
tetracycline. Resultant glycan patterns of the expressed glycoprotein are consistent
with those expressed by Expi293F™ GnTI- Cells. For best results, Expi293F
Inducible GnTI- Cells should be maintained under selective pressure of blasticidin.
For further details, see “Guidelines for inducible cells” on page 15.
™
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Expi293™ Expression System User Guide
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Components of the Expi293™ Expression System: structural biology and inducible expression modules
Expi293™ Expression Medium
Expi293™ Expression Medium is a chemically defined, serum-free, protein-free,
animal origin-free medium for growth and transfection of suspension-adapted human
embryonic kidney (HEK) 293 cells. It is specifically designed to support high density
culture of Expi293F™ cell lines as part of the Expi293™ Expression System for
scalable transient protein expression. Expi293™ Expression Medium is formulated
with GlutaMAX™ Supplement. It is ready to use and no supplementation is required.
The chemically defined formulation results in high lot-to-lot reproducibility and
reliability. Expi293™ Expression Medium contains no human or animal-origin
components. The medium is not recommended for adherent cell cultures.
Expi293™ Expression Medium exhibits the following features:
•
Supports growth of suspension Expi293F™ cultures to densities over
15 × 106 cells/mL.
•
Transfection compatible medium enables transfection eciencies of
approximately 80% using ExpiFectamine™ 293 Transfection Reagent
•
Enables sustained, high-level expression of high-density transiently transfected
cultures, achieving yields of up to 1 gram per liter of recombinant protein
•
Supports growth and transfection of Expi293F™ cells in culture formats of less
than 1 mL in multi-well plates to greater than 10 L in disposable bioreactors
•
Does not contain phenol red
Chapter 1 Product information
1
Expi293™ Met (-) Expression Medium
Expi293™ Met (-) Expression Medium is an optimized, chemically defined formulation
designed to support methionine labeling of proteins and transfection of 293 cells
(e.g., Expi293F™ cells) in suspension. The medium does not contain methionine,
protein, undefined lysates, or components of animal origin. Expi293™ Met (-)
Expression Medium is a complete, ready-to-use medium formulated with GlutaMAX
Supplement, but requires methionine supplementation. The medium is not
recommended for adherent 293 cell culture.
™
Expi293™ Expression System User Guide
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Chapter 1
1
Components of the Expi293™ Expression System: structural biology and inducible expression modules
Product information
ExpiFectamine™ 293 Reagent
ExpiFectamine™ 293 Reagent is optimized for the transfection of nucleic acids into
high-density Expi293™ cell cultures.
ExpiFectamine™ 293 Reagent has the following features:
•
Designed specifically for transfection of high-density suspension cell culture,
with matching transfection enhancers that boost transfection performance and
protein expression
•
Achieves protein yields 2- to 10-fold higher than other transfection reagents used
on high-density 293 cell cultures
•
Employs the same transient expression protocols typically used in current lowdensity 293 suspension culture systems to easily switch from low‑density
systems to the high yield, high-density Expi293™ Expression System
•
Provides robust and reproducible transfection results
•
Enables scalable transfections for culture volumes of less than 1 mL to greater
than 10 liters, while maintaining equivalent volumetric protein yields
ExpiFectamine™ 293 Transfection Enhancer 1
ExpiFectamine™ 293 Transfection Enhancer 1 is an optimized, chemically defined,
serum-free, protein-free, animal origin-free formulation designed to work in
conjunction with Expi293™ Expression Medium to support, high-density transient
transfections. ExpiFectamine™ 293 Transfection Enhancer 1 is a component of the
ExpiFectamine™ 293 Transfection Kit.
ExpiFectamine™ 293 Transfection Enhancer 2
ExpiFectamine™ 293 Transfection Enhancer 2 is a proprietary, animal origin-free
formulation developed to be used in conjunction with ExpiFectamine™ 293 Reagent
and ExpiFectamine™ 293 Transfection Enhancer 1 to enhance protein production,
resulting in maximal protein yields. ExpiFectamine™ 293 Transfection Enhancer 2 is a
component of the ExpiFectamine™ 293 Transfection Kit.
ExpiFectamine™ 293 Met (-) Transfection Enhancer 2
ExpiFectamine™ 293 Met (-) Transfection Enhancer 2 is a proprietary, animal originfree, methionine-free formulation developed to be used in conjunction with
ExpiFectamine™ 293 Reagent and ExpiFectamine™ 293 Transfection Enhancer 1 to
enhance protein production during metabolic protein labeling experiments.
ExpiFectamine™ 293 Met (-) Transfection Enhancer 2 is a component of the
ExpiFectamine™ 293 Met (-) Transfection Kit.
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Expi293™ Expression System User Guide
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Components of the Expi293™ Expression System: structural biology and inducible expression modules
Opti-Plex™ Complexation Buer
Opti-Plex™ Complexation Buer is a chemically defined, animal origin-free, serumfree, phenol red-free, methionine-free, and biotin-free buer used to complex plasmid
DNA with ExpiFectamine™ 293 Reagent.
Note: Opti-Plex™ Complexation Buer must be used when expressing proteins using
the ExpiFectamine™ 293 Met (-) Transfection Kit to ensure maximal incorporation of
labeled methionine into the expressed proteins. For routine transient transfections,
the absence of methionine in Opti-Plex™ will not impact transfection eciency and
protein expression levels.
pRABBIT IgG IRES-EmGFP Positive Control Vector
Chapter 1 Product information
1
pRABBIT IgG IRES-EmGFP Positive Control Vector is provided as a positive control
for transfection, expression, and evaluation of transfection eciency in Expi293F
cell lines. The rabbit IgG that is produced in Expi293F™ Cells after transfection with
the control vector is secreted into the culture medium, with the optimal yields
occurring 5–7 days posttransfection (typical yield range: 450–500 mg/L). Emerald
Green Florescent Protein (EmGFP) is an intracellular protein that can be used to
qualitatively assess Expi293F cell transfection by fluorescence microscopy,
fluoresescent plate reader, or flow cytometry, 24–96 hours posttransfection. For more
information on using the pRABBIT IgG IRES-EmGFP Positive Control Vector, see
Appendix B, “Positive control for transfection and expression”.
pcDNA™5/TO Mammalian Expression Vector
pcDNA™5/TO Mammalian Expression Vector is a 5.7 kb expression vector that
utilizes the complete CMV promoter and adds control elements from the bacterial
tetracycline resistance operon to eectively repress and derepress transcription from
one of the strongest mammalian promoter sequences known. The pcDNA™5/TO
vector allows tetracycline-regulated expression of the gene of interest in mammalian
host cells expressing the tetracycline repressor protein (TetR).
PNGase F Glycan Cleavage Kit
The PNGase F Glycan Cleavage Kit includes all components required to perform the
enzymatic removal of almost all N-linked oligosaccharides from glycoproteins. The kit
includes recombinant PNGase F enzyme, which cleaves N-glycan chains at the
innermost GlcNAc and asparagine residues of high mannose, hybrid, and complex
oligosaccharides.
™
Expi293™ Expression System User Guide
13
Page 14
2
Procedural guidelines for Expi293F™ cell culture
Note: The cell handling instructions below are applicable to all Expi293F™ cell lines
including Expi293F™ Cells, Expi293F™ GnTI- Cells, Expi293F™ Inducible Cells, and
Expi293F™ Inducible GnTI- Cells.
General cell handling
•
All solutions and equipment that come in contact with the cells must be sterile.
Always use proper aseptic technique and work in a laminar flow hood.
•
For all cell manipulations, mix the cells by gentle swirling and avoid vigorous
shaking and pipetting. Cell health is critical for maximal performance.
•
Expi293F™ cell lines are robust cell lines adapted to high-density growth
conditions with a doubling time of approximately 24 hours during log phase
growth.
Methods
Guidelines for thawing and storing cells
•
On receipt, either thaw the cells immediately into pre-warmed Expi293
Expression Medium or immediately place the frozen cells into vapor phase liquid
nitrogen storage until ready to use. Do not store the cells at –80°C.
•
Avoid short-term, extreme temperature changes. When storing cells in liquid
nitrogen following receipt on dry ice, allow the cells to remain in liquid nitrogen
for 3–4 days before thaw.
•
Before starting experiments, ensure to have cells that are established and have
frozen stocks on hand. On receipt, grow and freeze multiple vials of Expi293F
cells to ensure that you have an adequate supply of early-passage cells.
Guidelines for cell maintenance and subculturing
•
Allow freshly thawed cells to recover in culture for three or more passages postthaw before transfecting.
•
Use an automated cell counter or a hemocytometer with the trypan blue
exclusion method to determine cell viability. Log phase cultures should be ≥95%
viable.
•
When thawing or subculturing cells, transfer cells into pre-warmed medium.
•
Cell viability should be ≥90% within 4–7 days post-thaw with viable cell density
typically >1 × 106 viable cells/mL at this time; if viability is not ≥90%, cells should
be incubated for up to an additional 3 days in order to reach this criterion.
™
14
Expi293™ Expression System User Guide
Page 15
•
At the time of first subculture, cells should be subcultured when the viable cell
density reaches 1–3 × 106 viable cells/mL.
•
For general maintenance of cells, passage Expi293F™ cells when they reach a
density of approximately 3–5 × 106 viable cells/mL (i.e., early log-phase growth),
typically every 3–4 days.
Note: Cells that are subcultured at densities outside of this early log-phase
growth window can show longer doubling times and lower protein titers over
time. Modify the initial seeding density to attain the target cell density of 3–5 ×
106 viable cells/mL at the time of subculturing.
Guidelines for inducible cells
For Expi293F™ Inducible Cells or Expi293F™ Inducible GnTI- Cells:
•
For routine culture maintenance, add blasticidin to a final concentration of
20 µg/mL to culture medium.
•
Blasticidin can be present in the media during cryopreservation without
impacting cell health.
•
An inducible expression vector must be utilized in conjunction with the
Expi293F™ Inducible Cells and Expi293F™ Inducible GnTI- Cells. pcDNA™5/TO
expression vector is recommended for lowest levels of basal expression and
highest levels of expression upon induction with tetracycline.
•
We recommend making a 1 mg/mL tetracycline stock solution in water.
Chapter 2 Methods
Procedural guidelines for Expi293F™ cell culture
2
Expi293™ Expression System User Guide
15
Page 16
Chapter 2
2
Thaw and establish Expi293F™ cell lines
Methods
Guidelines for media
Expi293™ Expression Medium is formulated with GlutaMAX™ Supplement. For
suspension growth and transfection applications, use the Expi293™ Expression
Medium without any supplementation.
IMPORTANT! Expi293
use and store media protected from light.
Note: ExpiFectamine™ 293 Transfection Enhancer 1 can exhibit a slightly yellowish
tint. Internal studies show this has no impact on system performance or protein titer.
™
Expression Medium is sensitive to light. For optimal results,
Thaw and establish Expi293F™ cell lines
Note: The thawing and cell line establishment instructions below are applicable to all
Expi293F™ cell lines including Expi293F™ Cells, Expi293F™ GnTI- Cells, Expi293F
Inducible Cells, and Expi293F™ Inducible GnTI- Cells.
Required materials
•
One of the following Expi293F™ cell lines:
–
Expi293F™ Cells
–
Expi293F™ GnTI- Cells
–
Expi293F™ Inducible Cells
–
Expi293F™ Inducible GnTI- Cells
•
125-mL polycarbonate or PETG, non-baed, disposable, sterile, vented shaker
flask for culturing suspension cells, such as Nalgene™ Single-Use PETG
Erlenmeyer Flasks with Plain Bottom: Sterile
•
Expi293™ Expression Medium, pre-warmed to 37°C
•
Orbital shaker in a 37°C incubator with ≥80% relative humidity and 8% CO
•
Reagents and equipment to determine cell viability (e.g., hemocytometer with
trypan blue or cell counter)
™
2
Thaw Expi293F™ cells
1.
2.
3.
16
Remove one vial of cells from liquid nitrogen, then swirl in a 37°C water bath for
1 to 2 minutes to thaw the cells rapidly until only a small amount of ice remains.
Do not submerge the vial in the water.
Just before the cells are completely thawed, decontaminate the vial by wiping it
with 70% ethanol before opening it in a laminar flow hood.
Use a 2‑mL or 5‑mL pipette, to transfer the entire contents of the cryovial into a
125‑mL polycarbonate or PETG, disposable, sterile, vented Erlenmeyer shaker
flask containing 30 mL of Expi293™ Expression Medium, pre-warmed to 37°C.
Expi293™ Expression System User Guide
Page 17
Chapter 2 Methods
Subculture Expi293F™ cell lines
4.
Incubate the cells in a 37°C incubator with ≥80% relative humidity and 8% CO
on an orbital shaker platform according to the following table.
Shaker diameter Shake speed (rpm)
19 mm 125 ± 5
25 mm 120 ± 5
50 mm 95 ± 5
5.
Allow cells to culture for 3–4 days post-thaw, then determine viable cell density
and percent viability.
Note: At 24 hours post-thaw, viability may drop to 80%, but should not get
below 70%. It can take up to 7 days for cells to recover and reach ≥90% viability
post-thaw.
6.
Perform the first subculture when the viable cell density reaches 1–3 × 106 viable
cells/mL (typically 4–7 days post-thaw).
2
2
Subculture Expi293F™ cell lines
Note: The cell handling and cell freezing instructions below are applicable to all
Expi293F™ cell lines including Expi293F™ Cells, Expi293F™ GnTI- Cells, Expi293F
Inducible Cells, and Expi293F™ Inducible GnTI- Cells.
Required materials
•
Expi293F™ cell culture at 3–5 × 106 viable cells/mL
•
Expi293™ Expression Medium, pre-warmed to 37°C
•
Polycarborate or PETG, non-baed, disposable, sterile, vented shaker flask for
culturing suspension cells, such as Nalgene™ Single-Use PETG Erlenmeyer
Flasks with Plain Bottom: Sterile (Cat. No. 4115-0125)
•
Reagents and equipment to determine viable cell density and percent viability
(e.g., hemocytometer or an automated cell counter, trypan blue)
•
Orbital shaker in a 37°C incubator with ≥80% relative humidity and 8% CO
™
2
Expi293™ Expression System User Guide
17
Page 18
Chapter 2
2
Subculture Expi293F™ cell lines
Methods
Subculture Expi293F™ cells
1.
Use the viable cell density to calculate the volume of cell suspension required to
seed a new shake flask according to the recommended seeding densities in
Table 7 and the recommended culture volumes in Table 8.
Table 7 Recommended seeding densities for routine cell culture
maintenance
For cells ready 3 days post-subculture 0.4–0.5 × 106 viable cells/mL
For cells ready 4 days post-subculture 0.3–0.4 × 106 viable cells/mL
Table 8 Recommended volumes for routine cell culture maintenance in
vented, non-baed flask
Sub-culture timing Recommended seeding density
Flask size
125 mL 30–35 mL
250 mL 60–70 mL
500 mL 100–120 mL
1 L 220–240 mL
2 L 440–480 mL
3 L 800–1,000 mL
2.
Transfer the calculated volume of cells to fresh, pre-warmed Expi293
Culture
volume (mL)
Shake speed
125 ± 5 rpm (19 mm shaking diameter)
120 ± 5 rpm (25 mm shaking diameter)
95 ± 5 rpm (50 mm shaking diameter)
90 ± 5 rpm
85 ± 5 rpm
80 ± 5 rpm
™
Expression Medium in a shake flask.
3.
Incubate flasks in a 37°C incubator with ≥80% relative humidity and 8% CO2 on
an orbital shaker platform until cultures reach a density of
3–5 × 106 viable cells/mL.
Note: Do not let cells grow above 5 × 106 viable cells/mL during routine culture.
Note: Cells that are subcultured at densities outside of this early log-phase
growth window can show longer doubling times and lower protein titers over
time. Modify the initial seeding density to attain the target cell density of 3–
5 × 106 viable cells/mL at the time of subculturing.
18
4.
Repeat step 1 to step 3 to maintain or expand the cells for transfection.
Expi293™ Expression System User Guide
Page 19
Cryopreserve Expi293F™ cells
1.
Centrifuge the cells at 300 × g for 5 minutes to collect the cells at the bottom.
Chapter 2 Methods
Transfect Expi293F™ cell lines using ExpiFectamine™ 293 Transfection Kit
2
2.
Discard the supernatant, then gently resuspend the cells in ice cold Expi293
Expression Medium containing 10% DMSO by pipetting up and down.
3.
Dilute the cells in fresh Expi293™ Expression Medium containing 10% DMSO to
a final density of 1 × 107 viable cells/mL.
Note: Alternatively, conditioned medium obtained following centrifugation of the
cells before freeze down can be added to fresh Expi293™ Expression Medium in
the following ratios: 45% fresh Expi293™ Expression Medium, 45% conditioned
medium, and 10% DMSO to generate a conditioned freeze medium.
4.
Freeze the cells in an automated or manual controlled-rate freezing apparatus
following standard procedures.
For ideal cryopreservation, the freezing rate is a decrease of 1°C per minute.
5.
Transfer frozen vials to vapor phase liquid nitrogen for long-term storage.
Transfect Expi293F™ cell lines using ExpiFectamine™ 293
Transfection Kit
Note: The cell transfection instructions below are applicable to all Expi293F™ cell
lines including Expi293F™ Cells, Expi293F™ GnTI- Cells, Expi293F™ Inducible Cells,
and Expi293F™ Inducible GnTI- Cells.
™
For optimal transfection of high-density suspension Expi293F™ cell cultures, use the
ExpiFectamine™ 293 Reagent included in the transfection kits.
Unlike other serum-free media formulations, Expi293™ Expression Medium does not
inhibit transfection. Expi293™ Expression Medium is specifically formulated to enable
transfection without the need to change or add media pre- and posttransfection.
Note: For metabolic labeling of proteins using the ExpiFectamine™ 293 Met (-)
Transfection Kit, proceed to “Transfect Expi293F™ cell lines using ExpiFectamine
293 Met (-) Transfection Kit for metabolic protein labeling” on page 22.
™
Expi293™ Expression System User Guide
19
Page 20
Chapter 2
2
Transfect Expi293F™ cell lines using ExpiFectamine™ 293 Transfection Kit
Methods
Required materials
•
Expi293F™ cell culture in Expi293™ Expression Medium
•
Plasmid DNA preparation, sterile, free from phenol and sodium chloride, and
containing mostly supercoiled DNA
Note: We recommend isolating plasmid DNA using the PureLink™ HiPure
Plasmid Kit (For ordering information, see Appendix D, “Ordering information”).
To ensure sterility, DNA can be filtered through a 0.22-μm filter before use.
Note: Expi293F™ Inducible Cells and Expi293F™ Inducible GnTI- Cells require an
inducible expression vector (e.g., pcDNA™5/TO Mammalian Expression Vector)
for inducible expression of the protein of interest. For more information, see
Appendix D, “Ordering information”.
•
pRABBIT IgG IRES-EmGFP Positive Control Vector
•
ExpiFectamine™ 293 Transfection Kit
•
Opti-Plex™ Complexation Buer ( Opti-MEM™ I Medium can also be used)
•
Expi293™ Expression Medium, pre-warmed to 37°C
Note: Do not add antibiotics to culture media during transfection as this will
decrease transfection eciency. If necessary, antibiotics can be added to
cultures approximately 24 hours posttransfection.
•
Polycarborate or PETG, non-baed, disposable, sterile, vented shaker flask for
culturing suspension cells, such asNalgene™ Single-Use PETG Erlenmeyer
Flasks with Plain Bottom: Sterile
•
Orbital shaker in a 37°C incubator with ≥80% relative humidity and 8% CO
•
Reagents and equipment to determine viable cell density and percent viability
2
Guidelines for transfection
•
Use of transfection reagents other than the ExpiFectamine™ 293 Reagent to
transfect Expi293F™ cell cultures can substantially reduce performance.
•
Gently invert the ExpiFectamine™ 293 Reagent 4–5 times before use to ensure
thorough mixing.
•
Complexation of plasmid DNA and ExpiFectamine™ 293 Reagent takes place at
room temperature.
•
Incubate the ExpiFectamine™ 293/DNA complexes for 10–20 minutes before
adding to the cells. Longer incubation times can lead to slight reduction in
performance. Incubation times over 20 minutes are not recommended.
•
For Expi293F™ Inducible Cells or Expi293F™ Inducible GnTI- Cells only, the
presence of blasticidin will not impact transfection, thus, there is no need to
remove blasticidin before transfection.
•
For scaling up transfections, see Appendix C, “Scaling up transfections”.
20
Expi293™ Expression System User Guide
Page 21
Day −2: Subculture cells
Subculture and expand Expi293F™ cells until cell density reaches approximately
3–5 × 106 viable cells/mL.
Day −1: Seed cells
Seed Expi293F™ cells to a final density of 2.5–3 × 106 viable cells/mL, then allow
cells to grow overnight.
Day 0: Transfect cells
1.
Determine viable cell density and percent viability.
Viable cell density and percent viability should be 4.5–5.5 × 106 viable cells/mL
and ≥95%, respectivelly, to proceed with transfection.
2.
Dilute the cells to a final density of 3 × 106 viable cells/mL with fresh, prewarmed Expi293™ Expression Medium, then swirl the culture flasks gently to mix
the cells.
Chapter 2
Transfect Expi293F™ cell lines using ExpiFectamine™ 293 Transfection Kit
Methods
2
Note: Discard the remaining cells. Do not re-use high-density cells for routine
subculturing.
3.
Gently invert the ExpiFectamine™ 293 Reagent bottle 4–5 times before use to
ensure thorough mixing.
4.
Dilute plasmid DNA with Opti-Plex™ Complexation Buer (or Opti-MEM™ I
Medium), then mix by swirling or inversion.
Note: Total plasmid DNA concentration of 1.0 µg/mL of culture volume to be
transfected is appropriate for most proteins.
5.
Dilute ExpiFectamine™ 293 Reagent with Opti-Plex™ Complexation Buer (or
Opti-MEM™ I Medium, if used in step 4), then mix by swirling or inversion.
6.
Incubate at room temperature for 5 minutes.
7.
Add the diluted ExpiFectamine™ 293 Reagent to the diluted plasmid DNA, then
mix by swirling or inversion.
8.
Incubate the ExpiFectamine™ 293/plasmid DNA complexes at room temperature
for 10–20 minutes.
9.
Slowly transfer the complexes to the cells, swirling the culture flask gently during
addition, then incubate the cells in a 37°C incubator with ≥80% relative humidity
and 8% CO2 on an orbital shaker (for suggested shake speeds, see Table 9).
Expi293™ Expression System User Guide
21
Page 22
Chapter 2
2
Transfect Expi293F™ cell lines using ExpiFectamine™ 293 Met (-) Transfection Kit for metabolic protein labeling
Methods
Day +1: Add Enhancers
1.
18–22 hours posttransfection, add ExpiFectamine™ 293 Transfection Enhancer 1
and ExpiFectamine™ 293 Transfection Enhancer 2 to the transfection flask,
gently swirling the flask during addition.
Note: It is not necessary to pre-warm ExpiFectamine™ 293 Transfection
Enhancer 1 and ExpiFectamine™ 293 Transfection Enhancer 2 before addition.
ExpiFectamine™ 293 Transfection Enhancer 1 and ExpiFectamine™ 293
Transfection Enhancer 2 can be mixed together just before addition.
2.
(Optional) If transfecting Expi293F™ Inducible Cells or Expi293F™ Inducible GnTI-
Cells, add 1 mg/mL tetracycline to a final concentration of 1 µg/mL to induce
protein expression.
Note: Lower concentrations of tetracycline (ranging from 10 ng/mL to 1 µg/mL)
can be added to modulate the expression of the protein of interest in a dosedependent manner.
3.
Immediately return the flask to the 37°C incubator with ≥80% relative humidity
and 8% CO2 on an orbital shaker platform.
Day +5: Harvest protein
Optimal time to harvest protein depends on the specific properties of the protein
being expressed.
• For many secreted proteins, 5–7 days posttransfection is a typical harvest time
to reach maximum titer.
• For membrane proteins and intracellular proteins, 3–4 days is a typical harvest
time to reach maximum titer.
Transfect Expi293F™ cell lines using ExpiFectamine™ 293 Met (-)
Transfection Kit for metabolic protein labeling
Note: The cell transfection instructions below are applicable to all Expi293F™ cell
lines including Expi293F™ Cells, Expi293F™ GnTI- Cells, Expi293F™ Inducible Cells,
and Expi293F™ Inducible GnTI- Cells.
For optimal transfection of high-density suspension Expi293F™ cell cultures, use the
ExpiFectamine™ 293 Reagent included in the transfection kit.
Unlike other serum-free media formulations, Expi293™ Expression Medium does not
inhibit transfection. Expi293™ Expression Medium is specifically formulated to enable
transfection without the need to change or add media pre- and posttransfection.
22
Note: For routine transfections, proceed to “Transfect Expi293F™ cell lines using
ExpiFectamine™ 293 Transfection Kit” on page 19.
Expi293™ Expression System User Guide
Page 23
Transfect Expi293F™ cell lines using ExpiFectamine™ 293 Met (-) Transfection Kit for metabolic protein labeling
Required materials
Chapter 2
•
Expi293F™ cell culture in Expi293™ Expression Medium
•
Plasmid DNA preparation, sterile, free from phenol and sodium chloride, and
containing mostly supercoiled DNA
Note: We recommend isolating plasmid DNA using the PureLink™ HiPure
Plasmid Kit (For ordering information, see Appendix D, “Ordering information”).
To ensure sterility, DNA can be filtered through a 0.22-μm filter before use.
Note: Expi293F™ Inducible Cells and Expi293F™ Inducible GnTI- Cells require an
inducible expression vector (e.g., pcDNA™5/TO Mammalian Expression Vector)
for inducible expression of protein of interest. For more information, see
Appendix D, “Ordering information”.
•
pRABBIT IgG IRES-EmGFP Positive Control Vector
•
ExpiFectamine™ 293 Met (-) Transfection Kit
•
Expi293™ Met (-) Expression Medium, pre-warmed to 37°C
Note: Do not add antibiotics to culture media during transfection as this will
decrease transfection eciency. If necessary, antibiotics can be added to
cultures approximately 24 hours posttransfection.
•
Polycarborate or PETG, non-baed, disposable, sterile, vented shaker flask for
culturing suspension cells, such as Nalgene™ Single-Use PETG Erlenmeyer
Flasks with Plain Bottom: Sterile
•
Orbital shaker in a 37°C incubator with ≥80% relative humidity and 8% CO
•
Reagents and equipment to determine viable cell density and percent viability
Methods
2
2
Guidelines for transfection
•
Use of transfection reagents other than the ExpiFectamine™ 293 Reagent to
transfect Expi293F™ cell cultures can substantially reduce performance.
•
Gently invert the ExpiFectamine™ 293 Reagent 4–5 times before use to ensure
thorough mixing.
•
Complexation of plasmid DNA and ExpiFectamine™ 293 Reagent takes place at
room temperature.
•
Incubate the ExpiFectamine™ 293/DNA complexes for 10–20 minutes before
adding to the cells. Longer incubation times can lead to slight reduction in
performance. Incubation times over 20 minutes are not recommended.
•
For Expi293F™ Inducible Cells or Expi293F™ Inducible GnTI- Cells only, the
presence of blasticidin will not impact transfection, thus, there is no need to
remove blasticidin before transfection.
•
For scaling up transfections, see Appendix C, “Scaling up transfections”.
Day −2: Subculture cells
Subculture and expand Expi293F™ cells until cell density reaches approximately
3–5 × 106 viable cells/mL.
Expi293™ Expression System User Guide
23
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Chapter 2
2
Transfect Expi293F™ cell lines using ExpiFectamine™ 293 Met (-) Transfection Kit for metabolic protein labeling
Methods
Day −1: Seed cells
Seed Expi293F™ cells to a final density of 2.5–3 × 106 viable cells/mL, then allow
cells to grow overnight.
Day 0: Perform metabolic labeling
1.
Determine the number of cells required for transfection.
Nominally, 75 × 106 total cells are required for every 25 mL of culture to be
transfected (3 × 106 cells/mL). We recommend including at least 10% overage of
cells to account for any loss of cells on centrifugation.
2.
Centrifuge the required number of cells at 300 × g for 5 minutes.
3.
Discard the supernatant, then resuspend cells in fresh Expi293™ Met (-)
Expression Medium, pre-warmed to 37°C.
4.
Incubate the cells in a 37°C incubator with ≥80% relative humidity and 8% CO
on an orbital shaker platform for 5–7 hours to allow the cells to exhaust their
cellular supplies of methionine.
2
5.
Determine cell density and cell viability using an automated cell counter or the
trypan blue dye exclusion method.
Note: Viable cell density should be 3 × 106 cells/mL at ≥95% viability to
proceed with transfection. If necessary, dilute cell culture by adding fresh, prewarmed Expi293™ Met (-) Expression Medium to achieve 3 × 106 cells/mL.
6.
Immediately add labeled methionine to the culture flasks according to the
following table:
Methionine source
L-Methionine (Methyl-13C) 225 mg/L
L-Selenomethionine 50 mg/L
Note: Empirically optimize the concentration of labeled methionine for your
experiments.
Note: L-Selenomethionine is toxic to cells. Therefore, use the lowest
concentration required to achieve labeling of expressed protein.
Note: For metabolic labeling with L-Methionine (Methyl-13C), cells can be
cultured in Expi293™ Met (-) Expression Medium containing labeling reagent for
up to 3 passages before transfection. This strategy increases the eciency of LMethionine (Methyl-13C) incorporation into the protein of interest.
Final concentration
24
Expi293™ Expression System User Guide
Page 25
Transfect Expi293F™ cell lines using ExpiFectamine™ 293 Met (-) Transfection Kit for metabolic protein labeling
Day 0: Transfect cells
1.
2.
3.
4.
5.
Chapter 2
Methods
2
Determine viable cell density and percent viability.
If necessary, dilute the cells to a final density of 3 × 106 viable cells/mL with
fresh, pre-warmed Expi293™ Met (-) Expression Medium, then swirl the flask
gently to mix the cells.
Note: Discard the remaining cells. Do not re-use high-density cells for routine
subculturing.
Gently invert the ExpiFectamine™ 293 Reagent bottle 4–5 times before use to
ensure thorough mixing.
Dilute plasmid DNA with Opti-Plex™ Complexation Buer, then mix by swirling or
inversion.
Note: Total plasmid DNA concentration of 1.0 µg/mL of culture volume to be
transfected is appropriate for most proteins.
Dilute ExpiFectamine™ 293 Reagent with Opti-Plex™ Complexation Buer, then
mix by swirling or inversion.
6.
Incubate at room temperature for 5 minutes.
7.
Add the diluted ExpiFectamine™ 293 Reagent to the diluted plasmid DNA, then
mix by swirling or inversion.
8.
Incubate the ExpiFectamine™ 293/plasmid DNA complexes at room temperature
for 10–20 minutes.
9.
Slowly transfer the complexes to the cells, swirling the flask gently during
addition, then incubate the cells in a 37°C incubator with ≥80% relative humidity
and 8% CO2 on an orbital shaker (for suggested shake speeds, see Table 9).
Day +1: Add Enhancers
1.
18–22 hours post-transfection, add ExpiFectamine™ 293 Transfection
Enhancer 1 and ExpiFectamine™ 293 Met (-) Transfection Enhancer 2 to the
flask, gently swirling the flask during addition.
Note: It is not necessary to pre-warm ExpiFectamine™ 293 Transfection
Enhancer 1 and ExpiFectamine™ 293 Met (-) Transfection Enhancer 2 before
addition.
ExpiFectamine™ 293 Transfection Enhancer 1 and ExpiFectamine™ 293 Met (-)
Transfection Enhancer 2 can be mixed together just before addition.
Expi293™ Expression System User Guide
25
Page 26
Chapter 2 Methods
2
Transfect Expi293F™ cell lines using ExpiFectamine™ 293 Met (-) Transfection Kit for metabolic protein labeling
2.
(Optional) If transfecting Expi293F™ Inducible Cells or Expi293F™ Inducible GnTI-
Cells, add 1 mg/mL tetracycline to a final concentration of 1 µg/mL to induce
protein expression.
Note: Lower concentrations of tetracycline (ranging from 10 ng/mL to 1 µg/mL)
can be added to modulate the expression of the protein of interest in a dosedependent manner.
3.
Immediately return the flask to the 37°C incubator with ≥80% relative humidity
and 8% CO2 on an orbital shaker platform.
Day +5: Harvest protein
Optimal time to harvest protein depends on the specific properties of the protein
being expressed.
• For many secreted proteins, 5–7 days posttransfection is a typical harvest time
to reach maximum titer.
• For membrane proteins and intracellular proteins, 3–4 days is a typical harvest
time to reach maximum titer.
26
Expi293™ Expression System User Guide
Page 27
Additional guidelines
A
Guidelines to optimize protein expression
•
Expression levels will vary depending on the specific recombinant protein
expressed and the vector used; however, the Expi293™ Expression System will
exhibit consistent expression level for any particular protein from one
transfection to the next.
•
When expressing a protein for the first time, you may want to perform a time
course (e.g., harvest cells or media at several time points posttransfection) to
optimize the length of the expression run.
•
When expressing antibody molecules with the heavy and light chains encoded
on two separate plasmids, we also recommend optimizing the ratio of heavy
chain to light chain for each individual antibody. We recommend initial testing of
heavy chain:light chain ratio at 1:2.
Equipment
•
For optimal performance, it is critical that the shaking diameter, shaking speed,
flask size/type, and volume of culture to be transfected match the
recommendations in this protocol for both routine subculture and protein
expression runs.
•
Humidified incubators (≥80% relative humidity) are recommended to reduce
evaporation during expression runs. When using multi-well plates, high-humidity
settings should be used if available, as evaporation will be greater.
•
Ensure equipment is calibrated for temperature. In some instances, the total heat
from the incubator and the shaker can cause cell culture temperatures to exceed
the recommended ranges and lead to decreased cell growth, clumping or cell
death. In such instances, reduce the temperature setting of the incubator to
compensate for heat generated by the shaker.
•
Ensure that equipment is calibrated for CO2. Levels of CO2 should not exceed
8%.
Expi293™ Expression System User Guide
27
Page 28
A
Cells
Appendix A
Cells
Additional guidelines
•
Cells should exhibit growth profiles within the guidelines of the protocol during
routine cell culture maintenance (see “Expi293F™ Cells” on page 10).
Note: At 24 hours post-thaw, viability can drop to 80%, but should not get
below 70%. It can take up to 7 days for cells to recover and reach ≥90% viability
post-thaw.
•
Expi293F™ Cells are high-density cell lines: subculture cells when density has
reached log phase growth at 3–5 × 106 viable cells/mL. Subculturing cells before
they have reached log phase growth can negatively impact cell performance.
•
During all cell manipulations, mix the cells by gentle swirling; avoid vigorous
mixing/pipetting, especially immediately before transfection. Cell health prior to
transfection is critical to maximal performance.
•
Always keep dedicated cell culture maintenance flasks: do not re-purpose
remaining high-density cells from a transfection run for routine subculturing.
Plasmid DNA complexation
•
Plasmid DNA is highly stable in Opti-Plex™ Complexation Buer (or Opti-MEM™ I
Medium). After ExpiFectamine™ 293 Reagent is diluted with Opti-Plex™ or OptiMEM™ I Medium, mix by swirling the tube and/or inversion or gentle pipetting 2–
3 times. Do not vortex.
•
For optimal performance, once the diluted ExpiFectamine™ 293 Reagent is
added to diluted plasmid DNA, mix by swirling the tube and/or inversion or
gentle pipetting 2–3 times; do not vortex. Incubate 10–20 minutes postcomplexation before drop-wise addition to the flasks with swirling.
•
When using Expi293F™ Inducible Cells or Expi293F™ Inducible GnTI- Cells, an
inducible vector such as pcDNA™5/TO Mammalian Expression Vector must be
used to enable inducible expression of the protein of interest after treatment with
tetracycline.
Harvest
Proteins should be harvested when cells are at ~60% or greater viable cell density
posttransfection. Optimal time to harvest protein will depend on the specific
properties of the protein being expressed. 5-7 days posttransfection is a typical
harvest time to reach maximum titer for many secreted proteins. For membrane
proteins and intracellular proteins, 3-4 days is a typical harvest time.
28
Expi293™ Expression System User Guide
Page 29
Cell culture supernatant clarification
•
Following harvest, centrifuge the supernatant at 3,000–5,000 x g for 20–30
minutes in a refrigerated centrifuge.
•
Filter supernatant through a 0.22-μm filter.
Appendix A Additional guidelines
Cell culture supernatant clarification
A
Expi293™ Expression System User Guide
29
Page 30
Positive control for transfection and
B
Two dierent antibody expressing positive control vectors (with or without GFP) are
available for assessing expression conditions in the Expi293™ Expression System.
pRABBIT IgG IRES-EmGFP Positive Control Vector
pRABBIT IgG IRES-EmGFP Positive Control Vector is provided with the various
System Kits as a positive control for transfection and expression in Expi293F™ cell
lines. This control vector contains a mixture of pcDNA™3.4 plasmid clones expressing
the heavy and light chains of a rabbit IgG as well as Emerald Green Fluorescent
Protein (EmGFP). The control is provided as a ready-to-use transfection-grade
plasmid mix at a concentration of 1 mg/mL with a 1:2 heavy chain:light chain IgG
ratio and is sucient to transfect up to 150 mL of Expi293F™ cells.
expression
Transfection and expression
Note: The transfection conditions below are identical regardless of which Positive
Control Vector is to be used.
Transfect 25 mL of suspension Expi293™ cells using 25 µL of either of the positive
control vectors (i.e., 1 µg of positive control per 1 mL of Expi293™ culture) following
the protocol provided in “Transfect Expi293F™ cell lines using ExpiFectamine™ 293
Transfection Kit” on page 19.
The rabbit IgG that is produced in Expi293™ cells after transfection with either control
vector is secreted into the culture medium, with optimal yields obtained between 5–7
days (typical yield range: 450–500 mg/L).
When using pRABBIT IgG IRES-EmGFP Positive Control Vector, EmGFP
accumulates within the cells 24–96 hours post-transfection. GFP fluorescence can be
used to qualitatively assess cellular transfection by fluorescence microscopy,
fluorescent plate reader, or flow cytometry using standard GFP settings of 488 nm
excitation and 510 nm emission.
30
Expi293™ Expression System User Guide
Page 31
Scaling up transfections
C
Scale up transfections
You can scale up the Expi293F™ cell cultures in spinner flasks or bioreactors.
Determine the optimal spinner or impeller speed and seeding density for your culture
system. We recommend that the cells be seeded at 0.3 × 106 to 0.5 × 106 viable
cells/mL. Optimum spinner speed is approximately 100–130 rpm, and optimum
impeller speed in Celligen™ stirred tank bioreactors is 70–100 rpm. If the split ratio of
cells to fresh media is less than 1:2, centrifuge the cell suspension and re-suspend
the cell pellet in fresh medium before inoculating the culture.
Use the following conditions to scale up transfections:
Table 9 Recommended volumes for transfection at various scales
Vessel type
Number of cells
required
Culture volume to
transfect
Shake speed
Amount of plasmid
[2]
DNA
Volume of plasmid
DNA
Opti-Plex
Complexation Buer
or Opti-MEM™ I
Medium
[1]
(rpm)
™
[3]
96 deep
well plate
2.0 × 1067.5 × 10645 × 10
800 µL 2.5 mL 15 mL 25 mL 50 mL 200 mL 400 mL 800 mL
900 ± 50
(3 mm
orbital
shaking
diameter)
0.8 µL 2.5 µL 15 µL 25 µL 50 µL 200 µL 400 µL 800 µL
50 µL 150 µL 900 µL 1.5 mL 3 mL 12 mL 24 mL 48 mL
24 deep
well plate
225 ± 5
250 ± 5
235 ± 5
1.0 µg total plasmid DNA per mL of culture volume to transfect
Mini
Bioreactor
tube
6
240 ± 5
250 ± 5
245 ± 5
125 mL
flask
75 × 106150 × 106600 × 1061.2 × 10
125 ± 5 (19 mm orbital shaking diameter)
120 ± 5 (25 mm orbital shaking diameter)
95 ± 5 (50 mm orbital shaking diameter)
250 mL
flask
1 L flask 2 L flask 3 L flask
2.25 × 10
9
90 ± 5
90 ± 5
55 ± 5
9
ExpiFectamine™ 293
Reagent
Opti-Plex
Complexation Buer
or Opti-MEM™ I
Medium
Expi293™ Expression System User Guide
™
[4]
2.5 µL 8 µL 50 µL 80 µL 160 µL 640 µL 1.3 mL 2.6 mL
1.4 mL 140 µL 850 µL 1.4 mL 2.8 mL 11.2 mL 22.5 mL 45 mL
31
Page 32
Appendix C Scaling up transfections
C
Scale up transfections
Table 9 Recommended volumes for transfection at various scales (continued)
Mini
Bioreactor
tube
125 mL
flask
250 mL
flask
1 L flask 2 L flask 3 L flask
Vessel type
96 deep
well plate
24 deep
well plate
ExpiFectamine™ 293
Transfection
5 µL 15 µL 90 µL 150 µL 300 µL 1.2 mL 2.4 mL 4.8 mL
Enhancer 1
ExpiFectamine™ 293
Transfection
50 µL 150 µL 900 µL 1.5 mL 3 mL 12 mL 24 mL 48 mL
Enhancer 2
Final culture volume ~1 mL ~3 mL ~20 mL ~30 mL ~60 mL ~240 mL ~480 mL ~960 mL
[1]
Recommended shake speed ranges; optimal shake speed should be determined empirically based on the specific laboratory equipment used.
[2]
Assuming a plasmid DNA stock concentration of 1mg/mL and a final concentration of 1.0 μg plasmid DNA per mL.
[3]
Volume of Opti-MEM™ I Medium or Opti-Plex™ Complexation Buffer used to dilute plasmid DNA.
[4]
Volume of Opti-MEM™ I Medium or Opti-Plex™ Complexation Buffer used to dilute ExpiFectamine™ 293 Reagent.
32
Expi293™ Expression System User Guide
Page 33
D
Unless otherwise indicated, all materials are available through thermofisher.com.
Additional products
Ordering information
Item
Expi293F™ cells
Expi293F™ Cells (cGMP banked) 1 vial 100044202
Expi293F™ GnTI- Cells 1 mL
Expi293F™ Inducible Cells 1 mL
Expi293F™ Inducible GnTI- Cells 1 mL
Expi293™ Met (-) Protein Labeling Kit 1 kit A41249
ExpiFectamine™ 293 Transfection Kit
ExpiFectamine™ 293 Met (-) Transfection
Kit
Expi293™ Expression Medium 1 L A1435101
Amount Source
1 mL
6 × 1 mL A14528
1 kit for 1 L of
culture
1 kit for 1 L of
culture
A14527
A14527CN
A39240
A39240CN
A39241
A39241CN
A39242
A39242CN
A14524
A39249
Expi293™ Met (-) Expression Medium 1 L A4096701
Opti-Plex™ Complexation Buer 100 mL A4096801
pRABBIT IgG IRES-EmGFP Positive
Control Vector
Antibody-Expressing Positive Control
Vector
PNGase F Glycan Cleavage Kit 1 kit (500,000 units) A39245
pcDNA™5/TO Mammalian Expression
Vector
Expi293™ Expression System User Guide
1 kit A39243
1 vial A14662
1 kit V103320
33
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Appendix D Ordering information
D
Shaker flasks for suspension culture
(continued)
Item
pcDNA™ 3.4-TOPO™ TA Cloning Kit 1 kit A14697
L-Methionine (Methyl-13C) 225 mg A39248
L-Selenomethionine 250 mg A39247
Tetracycline Hydrochloride 500 mg
Trypan Blue Stain 100 mL 15250-061
Shaker flasks for suspension culture
Item
Nalgene™ Single-Use PETG Erlenmeyer
Flasks with Plain Bottom: Sterile
Amount Source
A39246
Capacity Source
125 mL 4115-0125
250 mL 4115-0250
500 mL 4115-0500
1,000 mL 4115-1000
Plasmid purification products
PureLink™ HiPure Plasmid Midiprep Kit 25 preps K210004
PureLink™ HiPure Plasmid Filter Midiprep Kit 25 preps K2100-14
PureLink™ HiPure Plasmid Maxiprep Kit 10 preps K210006
PureLink™ HiPure Plasmid Filter Maxiprep Kit 10 preps K2100-16
PureLink™ HiPure Expi Plasmid Megaprep Kit 4 preps K210008XP
Item
2,000 mL 4115-2000
2,800 mL 4115-2800
Amount Source
34
Expi293™ Expression System User Guide
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E
Safety
WARNING! GENERAL SAFETY. Using this product in a manner not specified in the
user documentation may result in personal injury or damage to the instrument or
device. Ensure that anyone using this product has received instructions in general
safety practices for laboratories and the safety information provided in this
document.
Before using an instrument or device, read and understand the safety information
·
provided in the user documentation provided by the manufacturer of the
instrument or device.
Before handling chemicals, read and understand all applicable Safety Data Sheets
·
(SDSs) and use appropriate personal protective equipment (gloves, gowns, eye
protection, and so on). To obtain SDSs, see the “Documentation and Support”
section in this document.
Expi293™ Expression System User Guide
35
Page 36
Appendix E Safety
E
Chemical safety
Chemical safety
WARNING! GENERAL CHEMICAL HANDLING. To minimize hazards, ensure
laboratory personnel read and practice the general safety guidelines for chemical
usage, storage, and waste provided below. Consult the relevant SDS for specific
precautions and instructions:
Read and understand the Safety Data Sheets (SDSs) provided by the chemical
·
manufacturer before you store, handle, or work with any chemicals or hazardous
materials. To obtain SDSs, see the "Documentation and Support" section in this
document.
Minimize contact with chemicals. Wear appropriate personal protective equipment
·
when handling chemicals (for example, safety glasses, gloves, or protective
clothing).
Minimize the inhalation of chemicals. Do not leave chemical containers open. Use
·
only with sucient ventilation (for example, fume hood).
Check regularly for chemical leaks or spills. If a leak or spill occurs, follow the
·
manufacturer cleanup procedures as recommended in the SDS.
Handle chemical wastes in a fume hood.
·
Ensure use of primary and secondary waste containers. (A primary waste container
·
holds the immediate waste. A secondary container contains spills or leaks from the
primary container. Both containers must be compatible with the waste material
and meet federal, state, and local requirements for container storage.)
After emptying a waste container, seal it with the cap provided.
·
Characterize (by analysis if needed) the waste generated by the particular
·
applications, reagents, and substrates used in your laboratory.
Ensure that the waste is stored, transferred, transported, and disposed of
·
according to all local, state/provincial, and/or national regulations.
IMPORTANT! Radioactive or biohazardous materials may require special handling,
·
and disposal limitations may apply.
36
WARNING! HAZARDOUS WASTE (from instruments). Waste produced by the
instrument is potentially hazardous. Follow the guidelines noted in the preceding
General Chemical Handling warning.
WARNING! 4L Reagent and Waste Bottle Safety. Four-liter reagent and waste
bottles can crack and leak. Each 4-liter bottle should be secured in a low-density
polyethylene safety container with the cover fastened and the handles locked in the
upright position.
Expi293™ Expression System User Guide
Page 37
Biological hazard safety
WARNING! Potential Biohazard. Depending on the samples used on this
instrument, the surface may be considered a biohazard. Use appropriate
decontamination methods when working with biohazards.
WARNING! BIOHAZARD. Biological samples such as tissues, body fluids,
infectious agents, and blood of humans and other animals have the potential to
transmit infectious diseases. Conduct all work in properly equipped facilities with the
appropriate safety equipment (for example, physical containment devices). Safety
equipment can also include items for personal protection, such as gloves, coats,
gowns, shoe covers, boots, respirators, face shields, safety glasses, or goggles.
Individuals should be trained according to applicable regulatory and company/
institution requirements before working with potentially biohazardous materials.
Follow all applicable local, state/provincial, and/or national regulations. The following
references provide general guidelines when handling biological samples in laboratory
environment.
Appendix E Safety
Biological hazard safety
E
U.S. Department of Health and Human Services, Biosafety in Microbiological and
·
Biomedical Laboratories (BMBL), 5th Edition, HHS Publication No. (CDC) 21-1112,
Revised December 2009; found at:
https://www.cdc.gov/labs/pdf/
CDC-BiosafetymicrobiologicalBiomedicalLaboratories-2009-P.pdf
World Health Organization, Laboratory Biosafety Manual, 3rd Edition,
·
WHO/CDS/CSR/LYO/2004.11; found at:
www.who.int/csr/resources/publications/biosafety/Biosafety7.pdf
Expi293™ Expression System User Guide
37
Page 38
Documentation and support
F
Customer and technical support
Visit thermofisher.com/support for the latest service and support information.
•
Worldwide contact telephone numbers
•
Product support information
–
Product FAQs
–
Software, patches, and updates
–
Training for many applications and instruments
•
Order and web support
•
Product documentation
–
User guides, manuals, and protocols
–
Certificates of Analysis
–
Safety Data Sheets (SDSs; also known as MSDSs)
Note: For SDSs for reagents and chemicals from other manufacturers,
contact the manufacturer.
Limited product warranty
Life Technologies Corporation and/or its aliate(s) warrant their products as set forth
in the Life Technologies' General Terms and Conditions of Sale at
www.thermofisher.com/us/en/home/global/terms-and-conditions.html. If you
have any questions, please contact Life Technologies at www.thermofisher.com/
support.
38
Expi293™ Expression System User Guide
Page 39
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29 May 2020
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