Cells expand exponentially in a stirred-tank bioreactor until the
batch reaches its target size, then the harvest is tested for
viability before it can be released as vialed product.
N(t) = N0 · 2^(t / doubling_time)
release = viability ≥ QC_threshold
- Autologous — one patient's own cells, small single-batch reactor, one vial per run, no immune mismatch but expensive per-dose logistics.
- Allogeneic — a donor "universal" cell line expanded to a large batch and split into many vials — cheaper per dose, needs tighter QC and cold-chain logistics.
- Expansion rate — how fast cells double; push it too high and viability at harvest drops.
- QC threshold — the minimum viability percentage a batch must clear before vials are released; failed batches are discarded, not filled.