Defective flow space limits the scaling up of turbulence bioreactors for platelet generation

To complement donor-dependent platelet supplies, we previously developed an ex vivo manufacturing system using iPSC-derived expandable megakaryocytes, imMKCLs, and a turbulent flow bioreactor, VerMES, to generate iPSC-derived platelet products (iPSC-PLTs). However, the tank size of VerMES was limited to 10 L (VerMES10). Here we examined the feasibility of scaling up to 50 L (VerMES50) with reciprocal motion by two impellers. Under optimized turbulence parameters corresponding to VerMES10, VerMES50 elicited iPSC-PLTs with intact in vivo hemostatic function but with less production efficiency. This insufficiency was caused by increased defective turbulent flow space. A computer simulation proposed that designing VerMES50 with three impellers or a new bioreactor with a modified rotating impeller and unique structure reduces this space. These findings indicate that large-scale PLT manufacturing from cultured imMKCLs requires optimization of the tank structure in addition to optimal turbulent energy and shear stress. RNA-sequencing (RNA-Seq)