Mesenchymal stromal cells (MSCs) are promising candidates for novel cell therapeutic applications. For clinical scale manufacturing, human factors from serum or platelets have been suggested as alternatives to fetal bovine serum (FBS). We have previously shown that pooled human serum (HS) and thrombin-activated platelet releasate in plasma (tPRP) support the expansion of adipose tissue-derived MSCs. Contradictory results with bone marrow (BM)-derived MSCs have initiated a comprehensive comparison of HS, tPRP, and pooled human platelet lysate (pHPL) and FBS in terms of their impact on MSC isolation, expansion, differentiation, and immunomodulatory activity. In addition to conventional Ficoll density gradient centrifugation, depletion of lineage marker expressing cells (RosetteSep) and CD271⁺ sorting were used for BM-MSC enrichment. Cells were cultured in medium containing either 10% FBS, HS, tPRP, or pHPL. Colony-forming units and cumulative population doublings were determined, and MSCs were maximally expanded. Although both HS and tPRP comparable to FBS supported isolation and expansion, pHPL significantly accelerated BM-MSC proliferation to yield clinically relevant numbers within the first two passages. MSC quality and functionality including cell surface marker expression, adipogenic and osteogenic differentiation, and immunosuppressive action were similar in MSCs from all culture conditions. Importantly, spontaneous cell transformation was not observed in any of the culture conditions. Telomerase activity was not detected in any of the cultures at any passage. In contrast to previous data from adipose tissue-derived MSCs, pHPL was found to be the most suitable FBS substitute in clinical scale BM-MSC expansion.

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