**5. Colony forming unit assay**

For these assays, cells of both thawed and noncryopreserved MSCs or cultures were plated at 1× 106 cells/ml and MSCs in culture showed a colony formation consisting of 40-80 cells in 25 cm² flasks for 14 days (Fig 3). After P9, the cells showed no colony forming ability which illustrated that colony forming ability decreases with increasing passages.

Fig 3. Phase contrast images of typical MSCs colony morphology before (A) and after (B) cryopreservation. Cell sphere formation in the MSCs culture produced colony formation units that stained with giemsa (A and B: x 40).
