Growth and functional harvesting of human mesenchymal stromal cells cultured on a microcarrier-based system

Human mesenchymal stromal cells (hMSCs) cells are attractive for applications in tissue engineering and cell therapy. Because of the low availability of hMSCs in tissues and the high doses of hMSCs necessary for infusion, scalable and cost-effective technologies for in vitro cell expansion are needed to produce MSCs while maintaining their functional, immunophenotypic and cytogenetic characteristics. Microcarrier-based culture systems are a good alternative to traditional systems for hMSC expansion. The aim of the present study was to develop a scalable bioprocess for the expansion of human bone marrow mesenchymal stromal cells (hBM-MSCs) on microcarriers to optimize growth and functional harvesting. In general, the results obtained demonstrated the feasibility of expanding hBM-MSCs using microcarrier technology. The maximum cell concentration (n = 5) was ~4.82 ± 1.18 × 10(5) cell mL(-1) at day 7, representing a 3.9-fold increase relative to the amount of inoculated cells. At the end of culture, 87.2% of the cells could be harvested (viability = 95%). Cell metabolism analysis revealed that there was no depletion of important nutrients such as glucose and glutamine during culture, and neither lactate nor ammonia byproducts were formed at inhibitory concentrations. The cells that were recovered after the expansion retained their immunophenotypic and functional characteristics. These results represent an important step toward the implementation of a GMP-compliant large-scale production system for hMSCs for cellular therapy.