Culture Expansion Alters Human Bone Marrow Derived Mesenchymal Stem Cell Production of Osteoarthritis-relevant Cytokines and Growth Factors.

Purpose: The purposes of this study were to characterize the human bone marrow derived mesenchymal stem cells (BM-MSCs) production of osteoarthritis-relevant cytokines and growth factors as they are purified and multiplied, a process termed culture expansion, and to compare the immunomodulatory potential of BM-MSCs based on source and medium used for culture expansion.

Methods: BM-MSCs were obtained from iliac crest bone marrow aspirates of four healthy donors. These four BM-MSC cell lines underwent four rounds, or "passages," of the institutional culture expansion protocol, using institutional culture media. The secretory molecules known to play a role in OA-related inflammatory immune response, cartilage degradation and patient symptoms, together called the BM-MSC "secretome," were measured at each passage. Three lines of commercially available BM-MSCs from healthy donors underwent culture expansion by the same protocol, using commercial culture media. The commercial BM-MSCs secretome and the institutional BM-MSCs secretome were compared at each passage. Significance was set at p<0.05.

Results: Institutional BM-MSCs produced less IL-6 at passages 3 (237±113 pg/mL) and 4 (237±113 pg/mL) compared to passages 1 (884±97 pg/mL) and 2 (1071±129 pg/mL; p<0.01). Institutional BM-MSCs produced more MIP-3α at passage 4 than at passage 1 (106±41 vs 32±7 pg/mL; p<0.01). Across passages of culture expansion, institutional BM-MSCs grown on institutional medium expressed more IL-6 (P<0.001), IL-10 (P<0.001), IL-1β (P<0.001), TNFα (P=0.004), and VEGF-C (P=0.003) than commercially available BM-MSCs grown on commercial medium.

Conclusion: Culture expansion alters key molecules within the BM-MSC secretome. Additionally, differences in BM-MSC source and culture medium alter the BM-MSC secretome and its immunomodulatory potential.