Size counts—from R&D to production
Stirred-tank bioreactors are available for a broad range of working volumes, with many choices of equipment and designs. They can be made of glass or stainless steel, but are also produced in polymeric single-use versions. The latter offer great potential for industrial applications in which a good manufacturing practice (GMP) environment is required.
Each stem cell line has its own specific requirements, which need to be figured out in the research and development phase. Early-stage experiments, for example, can be carried out in bioreactors with small working volumes (e.g., 100 mL) to save valuable cell material. Intelligent bioreactor design allows for smooth scale-up
to larger volumes, because of similar geometries, control systems, and comprehensive software. This ensures consistency throughout all development phases. Optimum growth conditions can be determined and seamlessly scaled to larger working volumes to produce sufficient amounts of stem cells for therapeutic or diagnostic applications.
Perfusion: The next big thing in stem cell cultivation?
Recent studies indicate that perfusion
cultivation, a feeding strategy quite well established in classical cell culture, will be suitable to grow iPSCs and other stem cells.
In perfusion culture, fresh medium is continuously added to the bioreactor while at the same time cell-free medium is withdrawn from the cultivation. In this way, the culture volume remains constant and cells experience an unchanging environment over a long period. Unlike continuous cultivations in general, perfusion techniques require retention of the cells using a filter or by binding them within the bioreactor using fibers or membranes.