Morphological characterization of bone marrow (BM)-derived mesenchymal stem cells (MSCs) cultured in different media at passage 2 (P2). The media were M1 (10% FBS + FGF2), M2 (10% FBS + 5% HPL), M3 (10% HPL), and M4 (5% HPL). Bar represents 100 μm. FBS, fetal bovine serum; FGF2, fibroblast growth factor 2; HPL, human platelet lysate. Representative results from 13 experiments are shown.