Fig. 2

In vitro morphological and behavioral features of hMuStem cells^HS and hMuStem cells^hPL. a Phase-contrast microscopy images of hMuStem cells^HS (upper panels) and hMuStem cells^hPL (lower panels) 7 days after initial seeding (left panels) and after four passages (P4). In exponential phase of amplification, both culture types consisted primarily of spindle-shaped cells, as well as small number of poorly adherent round cells (arrowheads). At day 6 from P4 (i.e., when cells reached confluence), May-Grünwald Giemsa staining of multinucleated cells revealed spontaneous fusion in hMuStem cells^HS (arrow, top right panels). In contrast, no multinucleated cells observed in hMuStem cells^hPL (bottom right panels). Scale bar, 100 μm. b Long-term proliferation kinetics of cultured hMuStem cells^HS (black) and hMuStem cells^hPL (gray) from three independent donors. c Frequency of colony-forming units (CFU) in hMuStem cells^HS and hMuStem cells^hPL at P4. Data presented as mean ± SD for each donor. Donors #4, #5, and #6 represented by squares, triangles, and circles, respectively. HS human serum, hPL human platelet lysate, D day, P passage, CPD cumulative population doubling