Figure 5.

v-PL can rejuvenate a culture of high passage mesenchymal stem cells (MSC). (A) A culture of bone marrow-derived mesenchymal stem cells (BM-MSC) previously expanded in the presence of 10% FCS for about 10 population doublings was split in the different culture conditions. After 3 weeks, one part of the cells of the culture in 10% Pl-s + 1% v-PL was transferred in medium supplemented with Pl-s without v-PL. After additional passages, at a time that proliferation was arrested (high passage cells), part of the Pl-s culture was transferred again in medium supplemented with 10% Pl-s + 1% v-PL (restoring in this way, the v-PL mitogenic stimulus). As shown by the graph, 1% v-PL cannot support cell proliferation, but the addition of v-PL to high passage cells, maintained in the presence of Pl-s as the only supplement, rejuvenate the cells that resume proliferation. (B) A scheme is reported to summarize the experiment in (A).