Fig. 4.

In vitrochondrogenic differentiation of UCSCs and infant BMSCs

(A) Chondrogenic pellets differentiated from UCSCs and infant BMSCs at early passages (3x10⁵ cells/pellet) on day 21. (Scale bar = 1 mm) (B) Measurement of the diameters of the 21-day differentiated pellets. The expression levels of: (C) SOX9 on day 7, (D) COL2, and (E) COL10 on day 21 of the UCSC- and infant BMSC-differentiated pellets, detected by RT-qPCR. The values were normalized to the expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The gene expression of the undifferentiated cells was used as the control to compare with that of the UCSC- and infant BMSC-differentiated chondrocyte-like cells, and the relative fold changes were shown. Mean ± SEM of values with three experimental replicates were expressed. Statistical differences were analyzed individually using the Mann-Whitney U test for the following groups: differences between UCSCs in the control and chondrogenic factor-induced medium (CIM) groups, differences between infant BMSCs in the control and CIM groups, differences between UCSCs and infant BMSCs in the control groups, and differences between UCSCs and infant BMSCs in the CIM groups. (F) Pellets of the 21-day chondrogenic differentiated UCSCs and infant BMSCs were sectioned and stained with Alcian blue, (G) anti-collagen type 2 (COL2), and (H) anti-collagen type 10 (COL10) antibodies to detect the protein expression levels by immunostaining. The intensities of each staining were measured and normalized with the whole backgrounds of the sections. The value of the UCSCs was used as the standard to compare with that of the infant BMSCs, and the relative fold changes were shown. Mean ± SEM of values with three experimental replicates were expressed. Statistical significance of comparing the UCSC- and infant BMSC-differentiated pellets was determined by the Mann-Whitney U test. The star symbol (∗) will indicate significant differences between the compared groups. “∗” represents p < 0.05. “∗∗” represents p < 0.01. “∗∗∗” represents p < 0.001.