Background: We have previously reported that adipose-derived stromal cells (ADSCs) isolated from rat subcutaneous adipose tissue (scADSCs) have osteogenic differentiation potential, whereas ADSCs from perirenal visceral adipose tissue (pvADSCs) do not. However, variations in the perirenal visceral adipose tissue mass (pvATM) of our experimental animals compelled us to investigate whether pvATM affected the differentiation potential of ADSCs, and whether the expression of lineage-specific markers or adipokines in naïve ADSCs could be correlated with differentiation potential in these cells.
Methods: Ethical approval was obtained from the Stellenbosch University Research Ethics Committee (Animal Care and Use). Subcutaneous and perirenal visceral adipose tissue samples were harvested from adult (250 g; ~12 weeks old) male Wistar rats fed on standard laboratory chow, and ADSCs were isolated by collagenase digestion. Based on differences in pvATM weight as a percentage of total body weight, the rats were divided into highVAT (1.261%±0.107% SD) and lowVAT (0.207%±0.044% SD) groups. Confluent ADSC cultures were treated with either osteoblast differentiation media (OM) or adipocyte differentiation media (AM). Matrix mineralisation and lipid accumulation were quantified with Alizarin Red S staining and Oil Red O staining, respectively. Gene expression levels were measured by semi-quantitative RT-PCR.
Results: Matrix mineralisation occurred in OM-treated cultures of lowVAT pvADSCs, in contrast with the non-osteogenic highVAT pvADSCs. LowVAT ADSCs differentiated into adipocytes after 12 days of AM treatment, compared with 7 days in highVAT ADSCs. Surprisingly, Msx2 and Runx2 expression levels in naïve ADSCs were not indicative of osteogenic or adipogenic potential. Leptin and adiponectin could not be detected, but TNFα expression was detectable in non-osteogenic highVAT pvADSCs.
Conclusions: Increased visceral adiposity and resultant inflammatory cytokine expression in the donor organism may influence the differentiation potential of pvADSCs and possibly scADSCs, and may have implications for cell-based therapies.
Disclosure: The authors declared no competing interests. This work was supported by the South African National Research Foundation and the South African Medical Research Council.