Expansion of adipose tissue mesenchymal stromal progenitors in serum-free medium supplemented with virally inactivated allogeneic human platelet lysate

BACKGROUND: Single-donor or pooled platelet lysates (PL) can substitute for fetal bovine serum (FBS) for mesenchymal stromal cell (MSC) expansion. However, for clinical applications of MSCs, the use of virally inactivated PL would be desirable. Recently, we have developed a solvent/detergent (S/D)-treated human PL preparation (S/D-PL) rich in growth factors. The capacity to use this virally inactivated preparation for MSC expansion needs to be evaluated. STUDY DESIGN AND METHODS: Platelet concentrates were treated by S/D (1% tri-n-butyl phosphate and 1% Triton X-45), extracted by oil, purified by C18 hydrophobic interaction chromatography, and sterile filtered. S/D-PL was compared to FBS as a medium supplement (10% vol/vol) for isolating, maintaining, and expanding adipose tissue-derived MSCs (AT-MSCs). Cell morphology; proliferation kinetics; immunophenotype; differentiation capacity toward the chondrogenic, osteogenic, and osteogenic lineages; and cytokine antibody array were assessed. RESULTS: AT-MSCs had a typical spindle morphology and proliferated in S/D-PL at least as well as in FBS. Immunophenotype at Passage 7 was characteristic of MSCs and similar for both culture conditions. Differentiation capacity into the three lineages was maintained and chondrogenesis was enhanced by S/D-PL. In a 120 human cytokine antibody array analysis, 73 cytokines were detected in S/D-PL, including 22 with a concentration higher than in FBS. CONCLUSION: S/D-PL is an alternative to FBS for AT-MSC maintenance and expansion, does not compromise the differentiation capacity nor the immunophenotype, and may accelerate chondrogenesis. S/D-PL protocols for MSC clinical scale-up may represent a major step toward challenging new use in stem cell therapies.