Figure 3

SEM image of hMSC mixture beads. (A) Structure in SEM of fibrin, thrombin, and atelocollagen without cells. (a) It is a mixed structure of fibrin and thrombin (fibrin; orange arrow, thrombin; yellow star). (b) The structure of only atelocollagen and the fibers are observed (**, yellow indication). (c) It is a mixed structure of fibrin, thrombin, and atelocollagen. The structures of collagen fiber (**, yellow indication) and fibrin is observed (orange arrow). (B) SEM image of fibrin, thrombin, and atelocollagen with cells. Control I group (mixture of fibrin, hMSCs, and thrombin cultured in basal medium; a, d, g, j), control II group (mixture of fibrin, hMSCs, and thrombin cultured in chondrogenic differentiation medium; b, e, h, k), and atelocollagen group (mixture of fibrin, atelocollagen, hMSCs, and thrombin cultured in chondrogenic differentiation medium; c, f, i, l) were investigated at 0, 3, 7, and 21 days after culture. Immediately after mixing, hMSCs showed round shape morphology in all groups (a–c, dotted line yellow circle). The atelocollagen group maintained the round shape up to 3 days after culture (f, yellow arrowhead), but the control I and II groups did not (d, e, yellow arrowhead). A large number of cells (* yellow indication) had surfaces in close contact with each other in all groups at 21 days (j–l). Chondrocyte-like morphology (spherical morphology) was only observed in the atelocollagen group (l, * yellow indication). Representative SEM images are shown. Scar bar: 200 nm (A (a–c)), 1 µm (B (a)), 2 µm (B (b, c, e–i)), 10 µm (B (d, j–l)).