Figure 3.

Cultures with commercial AB human sera gradually displayed senescence features. Initial cell growth in primary explants was comparable between foetal bovine serum (FBS) and HSs, as demonstrated by time-course of cell harvests (H) up to H2 (A) and similar morphology in culture (B, left column). Nevertheless, after 5–6 weeks, HS outgrowth cells gradually ceased proliferating, preventing further harvests (A) and assuming a flat vacuole-rich morphology (B), whereas in control explants, round phase-bright proliferating cells could still be detectable (black arrows), reaching H4 (A). Scale bars = 50 μm. H: harvest of cardiosphere-forming cells from primary explant culture. P: passage of CS-derived cells.