Manufacturing mesenchymal stromal cells for clinical applications: A survey of Good Manufacturing Practices at US academic centers

Background aims: Mesenchymal stromal cells (MSC) have gained prominence in the field of regenerative medicine due to their excellent safety profile in human patients and recently demonstrated efficacy in late-stage clinical studies. A prerequisite to achieving successful MSC-based therapies is the development of large-scale manufacturing processes that preserve the biological potency of the founder cell population. Because no standardized manufacturing process exists for MSCs, understanding differences in these processes among U.S. academic facilities would allow for better comparison of results obtained in the clinical setting. Methods: We collected information through a questionnaire sent to U.S. academic centers that produce MSCs under Good Manufacturing Practice conditions. Results: The survey provided information on the number and geographic location of academic facilities in the United States and major trends in their manufacturing practices. For example, most facilities employed MSCs enriched from bone marrow by plastic adherence and expanded in media supplemented with pooled human platelet lysate. Sterility testing and product identification via cell surface phenotype analysis were commonly reported practices, whereas initial and working cell plating densities, culture duration, product formulation and the intended use of the MSC product were highly variable among facilities. The survey also revealed that although most facilities assessed product potency, the methods used were limited in scope compared with the broad array of intended clinical applications of the product. Conclusions: Survey responses reported herein offer insight into the current best practices used to manufacture MSC-based products in the United States and how these practices may affect product quality and potency. The responses also provide a foundation to establish standardized manufacturing platforms.