Functional Structure of Adipocytes Differentiated from Human Umbilical Cord Stroma-derived Stem Cells

¹ Department of Histology and Embryology, Ankara University School of Medicine, Ankara, Turkey; Current Address: Infertility Clinics, Suleymaniye Maternity and Women's Health Research Training Hospital, Istanbul, Turkey
² Department of Medical Biology, Hacettepe University School of Medicine, Ankara, Turkey
³ Department of Histology and Embryology, Ankara University School of Medicine, Ankara, Turkey

^* To whom correspondence should be addressed. E-mail: alpcan{at}medicine.ankara.edu.tr.

	Abstract

It has been previously demonstrated that human umbilical cord stromal cells (HUCSCs) are competent to differentiate into adipocytes. However, controversies have arisen as to whether HUCSCs can become mature adipocytes or not, and to what extent these cells can be induced in adipogenic pathway. Here we extensively analyzed their adipogenic potency with a structural and functional approach by determining lipid formation dynamics in concordance to adipocyte-specific markers. During a 35-day period, HUCSCs respond to adipogenic induction, at which point 88% of cells exhibited multilocular lipid granules (LGs) having a mean diameter of 3 µm in round-shaped, F-actin poor cells. Although first week of induction did not generally display typical lipidogenic phenotypes, the degree of adipogenesis was dissected and confirmed by mRNA expressions of PPAR, C/EBP-, SREBP1, adipophilin, SCD1, GPD1, LIPE, adiponectin and leptin. All markers tested were found elevated in varying amounts (3-70 fold) around day 7 and reached a plateau after day 14 or 21 (5-335 fold). Perilipin as a surface protein around the LGs was exclusively confined to the enlarging LGs. Conclusively, we propose that after the termination of proliferation, HUCSCs possess the biochemical and cellular machinery to successfully differentiate into maturing adipocytes under adipogenic conditions, and this feature will ultimately allow these fetus-derived stem cells to be used for various therapeutic or aesthetic purposes.