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Adipose-derived stem cells (ASC) and its exosomes are gaining utmost importance in the field of regenerative medicine. The ASCs tested for their potential in wound healing are predominantly derived from the subcutaneous depot of lean donors. However, it is important to characterize the ASC derived from different adipose depots as these depots have clinically distinct roles.We characterized the ASC derived from subcutaneous and omental depots from a lean donor (sc-ASCn and om-ASCn) and compared it to the ASC derived from an obese donor (sc-ASCo and om-ASCo) using flow cytometry and real time qPCR.We show that stem cell markers Oct4, Sal4, Sox15, KLF4 and BMI1 have distinct expression patterns in each ASC. We evaluated the secretome of the ASC and characterized their secreted exosomes. We show long noncoding RNAs (lncRNAs) are secreted by ASC and their expression varied between the ASC's derived from different depots. Protein kinase C delta (PKCδ) regulates the mitogenic signals in stem cells. We evaluated the effect of silencing PKCδ in sc-ASCn, om-ASCn, sc-ASCo and om-ASCo. Using β-galactosidase staining, we evaluated the percentage of senescent cells in sc-ASCn, om-ASCn, sc-ASCo and om-ASCo. Our results also indicated that silencing PKCδ increases the percentage of senescent cells.Our case-specific study demonstrates a role of PKCδ in maintaining the adipose stem cell niche and importantly demonstrates depot-specific differences in adipose stem cells and their exosome content.

Adipose-derived stem cells (ADSC) were isolated and characterized from lean and obese subjects. We previously reported that distinct differences were observed in differentiating lean and obese preadipocytes. Protein kinase C delta (PKCδ) is alternatively spliced and has important roles in apoptosis. PKCδI promotes apoptosis and PKCδVIII promotes survival. Our previous data indicated an increase in the survival kinase, PKCδVIII in ADSC derived from an obese donor. We also determined that obese adipocytes were resistant to apoptosis. Here, we determine the relationship between a survival kinase PKCδVIII and hTERT expression in adipose derived stem cells from a lean and obese subject.We evaluated the telomerase activity and human telomerase reverse transcriptase (hTERT) expression in lean and obese ADSC. The lean and obese ADSC were purchased as cryopreserved cells from ZenBio™ (Research Triangle Park, NC, USA). Analyses were performed using PRISM™ software and analyzed using two-tailed Student's t-test.We observed an increase in telomerase in differentiating obese ADSC using western blot analysis. We determined the levels of hTERT splice variants. hTERT α+/β+ splice variant was increased after transfected of PKCδVIII. We next determined whether PKCδVIII over-expression affected the levels of telomerase. The results indicate an increase in telomerase with PKCδVIII over-expression.Over-expression of PKCδVIII in lean ADSC substantially increased expression of hTERT and telomerase. The decreased senescence seen in obese ADSC may in part be attributed to PKCδVIII. Obese ADSC undergo lower senescence and may have increased growth potential. These results propose a larger epigenetic modification in obese ADSC compared to lean ADSC.

Obesity and its comorbidities affect millions of people. Here, we demonstrate that human preadipocytes are susceptible to programmed cell death (apoptosis) while mature adipocytes are resistant to apoptosis. The molecular mechanisms underlying the phenotype of apoptosis-resistant adipocytes are lesser known. To study the role of apoptosis and define molecular differences in the developmental process of adipogenesis, human preadipocytes were differentiated in vitro to mature adipocytes. Many genes in the apoptosis pathway are alternatively spliced. Our data demonstrates that during differentiation PKC δ , Bclx, and Caspase9 switch to their prosurvival splice variants along with an increase in Bcl2 expression when the cells terminally differentiate into mature adipocytes. Next we determined the expression pattern of these genes in obesity. Our data indicated high expression of PKC δ VIII in adipose tissue of obese patient in different depots. We demonstrate a shift in the in vitro expression of these splice variants in differentiating preadipocytes derived from obese patients along with a decrease in adipogenesis markers. Hence, the programmed splicing of antiapoptotic proteins is a pivotal switch in differentiation that commits adipocytes to a prosurvival pathway. The expression pattern of these genes is dysregulated in obesity and may contribute to adipose tissue dysfunction.