Adherent expansion of CHO-K1 and HEK-293 cells in a rotating polylactic-acid bioreactor: a scalable bioprocess.

Adherent cell expansion at intermediate scale (<10,000 cm²) typically relies on parallelized T-flasks, roller bottles, multilayer stacks, fixed-bed bioreactors, or microcarriers, each involving trade-offs in handling complexity, shear stress, medium economy, or plastic waste. The CellScrew® addresses these limitations by replacing multiple petroleum-derived vessels with one polylactic acid (PLA) vessel. During rotation, its concentric cylinders arranged in an Archimedean screw generate a fluid film distributing medium and dissolved gases under low-shear while cells remain attached. This substantially reduces incubator footprint: one shelf accommodates three CellScrew® 6Ks compared with 36 T175s, roughly tripling growth area while lowering material use and handling time. We describe a reproducible protocol for CHO-K1 and HEK-293 expansion in the 850 cm² and 6,000 cm² formats, covering inoculation from T-flask seed trains, in-process supernatant monitoring, and harvest. Quantified attachment, proliferation kinetics, harvest efficiency, and post-thaw recovery showed consistent performance and transferability to other adherent cells.•Expansion standardized in both formats, reaching 200,000 cells/cm² (CHO-K1; 850 cm²) and 361,000 cells/cm² (HEK-293; 6,000 cm²).•Mechanical-enzymatic harvest recovers 94 ± 1% of cells at >93% viability.•HEK-293 attachment within first 24 h from polystyrene without multi-passage adaptation.•In-process metabolite monitoring as an indirect readout of culture density.