Human platelet lysate enhances proliferation but not chondrogenic differentiation of pediatric mesenchymal progenitors.

BACKGROUND AIMS: Cell therapies have the potential to improve reconstructive procedures for congenital craniofacial cartilage anomalies such as microtia. Adipose-derived stem cells (ADSCs) and auricular cartilage stem/progenitor cells (CSPCs) are promising candidates for cartilage reconstruction, but their successful use in the clinic will require the development of xeno-free expansion and differentiation protocols that can maximize their capacity for chondrogenesis. METHODS: We assessed the behavior of human ADSCs and CSPCs grown either in qualified fetal bovine serum (FBS) or human platelet lysate (hPL), a xeno-free alternative, in conventional monolayer and 3-dimensional spheroid cultures. RESULTS: We show that CSPCs and ADSCs display greater proliferation rate in hPL than FBS and express typical mesenchymal stromal cell surface antigens in both media. When expanded in hPL, both cell types, particularly CSPCs, maintain a spindle-like morphology and lower surface area over more passages than in FBS. Both media supplements support chondrogenic differentiation of CSPCs and ADSCs grown either as monolayers or spheroids. However, chondrogenesis appears less ordered in hPL than FBS, with reduced co-localization of aggrecan and collagen type II in spheroids. CONCLUSIONS: hPL may be beneficial for the expansion of cells with chondrogenic potential and maintaining stemness, but not for their chondrogenic differentiation for tissue engineering or disease modeling.