HEK293T vs. HEK293F vs. HEK293FT: Which Serum-Free Medium Does Each Need?

HEK293T vs. HEK293F vs. HEK293FT: Which Serum-Free Medium for Each? | SeamlessBio

HEK293 is not one cell line. It is a family — and each member has distinct characteristics that affect medium selection. Using a formulation optimised for one sub-line on another is one of the most common sources of suboptimal titre in viral vector manufacturing.

Here is what you need to know about the main HEK293 variants and their serum-free medium requirements.

HEK293 Parental

The original cell line, derived from human embryonic kidney cells transformed with adenovirus 5 DNA in 1973. Adherent, moderate growth rate, well characterised.

Medium requirements: Standard chemically defined formulation supporting adherent culture. Transfection efficiency with PEI is high in properly formulated serum-free conditions. Suitable for early-stage AAV production and recombinant protein expression.

HEK293T

HEK293T contains a stable integration of the SV40 Large T antigen. This allows episomal replication of plasmids containing the SV40 origin of replication — which dramatically increases transient protein expression and is the basis for high-efficiency triple plasmid transfection for AAV and lentiviral vector production.

HEK293T is adherent. It does not adapt well to suspension culture without significant selection and adaptation work.

Medium requirements: Optimised for adherent culture. Low albumin content is important — albumin interferes with PEI-DNA complex formation and uptake. The medium must support very high confluence (70–80% at transfection) without inducing early senescence. Post-transfection viability for 48–72 hours is the critical window.

HEK293F

HEK293F is a suspension-adapted variant of HEK293. It does not contain the SV40 T antigen. It is the preferred cell line for large-scale recombinant protein expression and is increasingly used for suspension AAV production platforms.

Medium requirements: Formulated specifically for suspension culture. High-density growth capability — commercially optimised HEK293F media support viable cell densities above 3–5 × 10⁶ cells/mL routinely. Agitation tolerance is important: the medium must maintain cell viability under the shear conditions of spinner flasks, shake flasks and stirred-tank bioreactors.

HEK293F requires serum-free suspension medium from the outset. Attempting to adapt using stepwise FBS reduction in a medium formulated for adherent culture typically results in poor growth and high cell death.

HEK293FT

HEK293FT combines the SV40 T antigen of HEK293T with selection for fast growth and high transfection efficiency. It is the standard cell line for high-titre lentiviral vector production.

Medium requirements: Similar to HEK293T — adherent format, low albumin, high confluence pre-transfection. The additional selection for fast growth means HEK293FT cultures can be denser at transfection than standard HEK293T, which requires the medium to support slightly higher metabolic demand during the productive phase.

HEK293-EBNA

Contains a stable integration of EBNA-1, enabling episomal replication of plasmids with the EBV origin of replication. Used primarily for transient expression of secreted proteins.

Medium requirements: EBNA-1 expression adds metabolic load. Medium formulations for HEK293-EBNA should support both adherent and early suspension adaptation, as many EBNA protocols involve scale-up in suspension formats.

Summary

Sub-line	T antigen	Culture format	Primary use	Key medium requirement
HEK293	No	Adherent	AAV, protein expression	Standard CD, low albumin
HEK293T	SV40	Adherent	AAV, lentiviral vectors	Low albumin, high confluence support
HEK293F	No	Suspension	Scale-up protein, AAV	High density, agitation tolerant
HEK293FT	SV40	Adherent	High-titre lentiviral	Fast growth support, low albumin
HEK293-EBNA	EBNA-1	Adherent/suspension	Transient secreted protein	EBNA-1 compatible, scalable

→ SeamlessBio supplies serum-free media for HEK293 cells across adherent and suspension formats, with options for AAV production, lentiviral vector manufacturing and recombinant protein expression: Serum-Free Media for HEK293 Cells