“…3 In some cases, MSCs can be expanded through 30-40 population doublings (10 9 -10 12 :1 expansion), whereas other preparations stop proliferating after 4-5 population doublings (50:1 expansion). [4][5][6] This different behavior may be because of multiple factors, such as the protocol used to obtain the bone marrow, [4][5][6][7] the low frequency of MSCs in marrow, 8 and the age and condition of the donor. 5,9 Interestingly, the loss of differentiation potential is not generalized.…”