The effect of fetal bovine serum (FBS) on efficacy of cellular reprogramming for induced pluripotent stem cell (iPSC) generation

Induced pluripotent stem cells (iPSCs) are pivotal to the advancement of regenerative medicine. However, the low efficacy of iPSC generation and insufficient knowledge about the reprogramming mechanisms involved in somatic cell/adult stem cell reversion to a pluripotent phenotype remain critical hurdles to the therapeutic application of iPSCs. The present study investigated whether the concentration of fetal bovine serum (FBS), a widely employed cell culture additive, can influence the cellular reprogramming efficacy (RE) of human adipose-derived stem cells (hADSCs) to generate iPSCs. Compared with the typically employed concentration of FBS (10%), high concentrations (20% and 30%) increased the RE of hADSCs by approximately twofold, whereas a low concentration (5%) decreased the RE by the same extent. Furthermore, cell counting kit-8 (CCK-8), bromodeoxyuridine (BrdU) incorporation, and fluorescence-activated cell sorting (FACS) assays showed that hADSC proliferation during reprogramming was significantly enhanced by FBS at 20% and 30%, whereas quantitative polymerase chain reaction (qPCR) and Western blotting assays revealed a concomitant decrease in p53, p51, and p21 expression. In addition, the efficacy of retrovirus-mediated transduction into hADSCs was increased by approximately 10% at high concentrations of FBS. It was confirmed that plateletderived growth factor in the FBS enhanced proliferation and reprogramming efficacy. Finally, the generated iPSCs showed a normal karyotype, the same fingerprinting pattern as parental hADSCs, a genome-wide transcriptome pattern similar to that of human embryonic stem cells (hESCs), and in vivo pluripotency. In conclusion, the current investigation demonstrated that high concentrations of FBS can modulate molecular and cellular mechanisms underlying the reprogramming process in hADSCs, thereby augmenting the cellular RE for iPSC generation.