Figure 7

Histological analysis of chondrogenic markers in hMSC beads. (A) Staining of fibrin, thrombin, and atelocollagen in the absence of cells. The gel beads without cells were cultured in chondrogenic differentiation medium on day 21. (a) Hematoxylin–eosin demonstrated weak eosin staining (weak pink color) and one large mass without empty space. (b) Weak Alcian blue pH 2.5 and (c) toluidine blue staining was observed. (e) Type I and (d) type II collagen staining did not demonstrate brown expression. Scale bar: 20 µm. (B) Staining of fibrin, thrombin, and atelocollagen with cells. Representative histological images of the control I group (mixture of fibrin, hMSCs, and thrombin cultured in basal medium), control II group (mixture of fibrin, hMSCs, and thrombin cultured in chondrogenic differentiation medium), and atelocollagen group (mixture of fibrin, atelocollagen, hMSCs, and thrombin cultured in chondrogenic differentiation medium) at 21 days after culture. Hematoxylin–eosin staining showed well mixed cells and a structure similar to lacunae (k, black arrow) compared to the other groups (a and f). Alcian blue pH 2.5 and toluidine blue staining showed expression around cells in the atelocollagen group (l and m), and the control I and II groups contained weak expression in the densely packed cells (b and g, c and h). Type II collagen was highly expressed around chondrocyte-like cells in the atelocollagen group (n) and weakly expressed in the control II group (i) compared to the control I group (d). Type I collagen staining was not observed in the control II and atelocollagen groups (j and o). Nevertheless, gel beads of the control I group were weakly expressed (e). Scale bar; 20 µm.