A quantitative analysis of multilineage-differentiating stress-enduring (Muse) cells in human adipose tissue and efficacy of melanocytes induction

We have shown previously that multilineage-differentiating stress-enduring (Muse) cells in neonatal fibroblasts can differentiate into functional melanocytes. In this study, we quantitate Muse cells in adipose-mesenchymal stem cells (adipose-MSCs) of human subcutaneous tissue obtained from 11 subjects of various ages, and measured efficacy of melanocytes induction from Adipose-MSC-derived Muse cells (hASC-Muse cells). There was a statistically significant negative correlation between the age of donors and the numbers of adipose-MSCs recovered per g fat as well as the percentage of SSEA3+ cells in the adipose-MSC populations, but isolated hASC-Muse cells showed pluripotency and growth curves equally regardless the age of donors. Adipose-Muse cells sequentially expressed melanocyte-related genes including KIT, MITF, TYRP1 PMEL, DCT, melanocortin 1 receptor (MC1R), and TYR at a comparable level to melanocytes during 6-week culture. Parallel with MC1R expression, adipose-Muse cells increased melanin content by α-MSH stimulation. By quantitating the cell numbers recovered at each step, we found that 10 g of adipose tissue could produce at least 2.5 × 106 melanocytes after 6 weeks of culture. These studies suggest that induction of melanocytes from adipose-Muse is a novel approach to obtain sufficient numbers of melanocytes for clinical application and in vitro study of melanocyte differentiation.