Microbioreactor-Based Production of Anchorage-Dependent Mesenchymal Stromal Cells Primed for Acute Respiratory Distress Syndrome

Cell-based therapy is an emerging therapeutic approach for a range of health conditions. However, producing sufficient quantities of quality cells remains an active scientific and technical challenge. The final cell product cannot be sterilized; therefore, sterility and quality-by-design considerations are paramount. For cells that are anchorage-dependent, flask-based expansion is still utilized at the development and industrial scales, requiring large physical footprints, limiting control of the biochemical environment (pH, CO2 and O2, diffusional gradients of nutrients and metabolites), and providing physical cues that can affect final cell quality. These challenges have motivated the adoption of bioreactor-based manufacturing approaches, but such approaches typically proceed at volumetric scales that confer challenges and can be cost-prohibitive for exploratory benchtop research or process development. Microbioreactor-microcarrier cell therapy production has been reported to provide biochemical control during culture for a test case of cell source type - mesenchymal stromal cells. For initial assessment of cell quality in vitro, acute respiratory distress syndrome was considered as a potential use case. The approach illustrated here enables rapid process development at benchtop scale due to the small (2 mL) volume and tight biochemical control in the microbioreactor. To achieve this for an anchorage-dependent cell type such as mesenchymal stromal cells required substantial modification of the microbioreactor process and utilized a gelatin microcarrier platform produced in-house through a microfluidic process. Here, additional detail is illustrated for the method and process parameters used to culture such anchorage-dependent cells in the microbioreactor, with the intention to enable other researchers to adapt these practices for their own use cases and cell source types.