The science

Higher yield, engineered into the producer cell

Most efforts to raise viral vector titer focus on the process: media, feeds, transfection conditions. ExtraCell works one level deeper: we re-programme the producer cell itself, so it devotes more of its machinery to building virus.

The bottleneck

Producer cells are not optimised to make virus

Cell lines such as HEK293 are workhorses for manufacturing AAV and lentiviral vectors, but they were never evolved for the job. A large share of their biosynthetic and secretory capacity is spent on genes and pathways that don't contribute to, and can actively limit, vector production.

The result is low, variable production yield: more batches, bigger facilities, and a cost per dose that can reach millions in gene therapy.

Plasmids and a transfection agent form a complex taken up by producer cells. HEK293 cells release few viral vectors; Extra-HEK293 cells release many more. — Given the same plasmids and transfection agent, **Extra-HEK293®** releases substantially more viral vectors than the parental HEK293 line.

The mechanism

Down-regulating the right genes remodels the secretory pathway

Guided by our understanding of the secretory cell machinery, ExtraCell identifies genes whose controlled down-regulation re-balances the cell toward high-yield vector output. Our lead target, EXT1, is one such gene.

Knocking down EXT1 reshapes the early secretory pathway (the endoplasmic reticulum (ER) and Golgi) and the organisation of protein complexes at the ER membrane, expanding the cell's capacity to fold, traffic and release recombinant product. Crucially, it's not only which gene, but the precise level of regulation that matters.

EXT1
Our lead down-regulation target: the trigger for the remodelling.
SEC61
The translocon channel that threads nascent chains into the ER.
CNX
Calnexin: folding and quality control of new proteins.
RTNs / ATL
Reticulons and atlastin that shape ER tubules and membrane dynamics.
SERCA2
Calcium pump maintaining the ER environment for secretion.

Side-by-side illustration of a control cell versus an EXT1-knockdown cell, showing changes in ER, Golgi and secretion, with a zoom on protein complexes at the ER membrane. — Control (CTRL) vs. EXT1 knockdown (EXT1 KD): remodelling of the ER and Golgi and of ER-membrane protein complexes, with increased secretion at the cell surface.

Patent WO2021165484

ExtraCell's cell-engineering approach is protected by an international patent, validated on experimental AAV production data: a defensible foundation covering mammalian producer cells.

What it delivers

More vector per batch, lower cost per dose

In head-to-head triple-plasmid AAV2 production, engineered cells out-produce the parental line, translating into fewer batches, smaller footprints and, in gene therapy, roughly half the manufacturing cost per patient.

AAV · LV

Vector-agnostic

Validated for AAV and applicable to lentiviral vector production.

Drop-in

No process change

Same transfection and upstream process: the gains come from the cell.

Roadmap

Beyond HEK293

Extra-CHO, Extra-MDCK, Extra-Vero and Extra-iPSC lines in development.

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