MScs

MSCs, or mesenchymal stem/stromal cells, are a heterogeneous population of non-hematopoietic cells with the capacity for self-renewal and differentiation toward osteoblasts, adipocytes, and chondrocytes under defined in vitro conditions. They are widely studied for regenerative medicine due to their potential to promote tissue repair and modulate immune responses.

Identity and sources: The International Society for Cellular Therapy defines MSCs as plastic-adherent cells in standard culture; they express CD105, CD73, and CD90, and lack CD45, CD34, CD14 or CD11b, CD19, and HLA-DR. MSCs are found in bone marrow, adipose tissue, umbilical cord and placenta, dental pulp, and other tissues, and are thought to reside in perivascular niches.

Functions and mechanisms: In addition to differentiation potential, MSCs secrete a broad range of trophic factors and extracellular vesicles that influence cell survival, angiogenesis, and tissue remodeling. They have immunomodulatory effects, including inhibition of T cell proliferation and modulation of B cells, natural killer cells, and dendritic cells, contributing to a permissive microenvironment for healing.

Clinical use and regulatory status: MSCs have been studied in many clinical trials for graft-versus-host disease, osteoarthritis, cartilage repair, myocardial infarction, and inflammatory conditions. Some therapies are approved in certain jurisdictions, but regulatory status varies. Challenges include cell heterogeneity, donor variability, manufacturing standardization, and the need for robust potency and safety assays.

Safety and challenges: Most studies report favorable short- to mid-term safety, with low risk of tumorigenicity, but long-term effects remain under investigation. Issues include defining standardized potency measures, scalable manufacturing, and ensuring consistent product quality across sources and batches.