[Leptin induced apoptosis in rat adipose-derived stem cells cultured in vitro]

To determine the direct effect of leptin on adipose tissue apoptosis in vitro using rat adipose-derived stem cells (ADSCs), we isolated the ADSCs of rat epididymis adipose tissue by collagenase digestion, filtration, and subsequent centrifugation. Cell cultures with or without leptin (10(-9) mol/L, 10(-8) mol/L, 10(-7) mol/L and 10(-6) mol/L) were incubated for different time. We examined the cell surface phenotype by immunofluorescence and detected the apoptosis morphological changes of ADSCs by laser scanning confocal microscope (LCSM). The number of apoptotic cells was determined by flow cytometry assay after annexin V binding and PI staining. Caspase-3 activity was measured by spectrofluorometry. The present study demonstrates that leptin treatment causes a marked increase in adipose-derived stem cell apoptosis. With the LCSM, after being treated with leptin, ADSCs showed the typical characteristic of apoptosis. Leptin in used concentrations (0 mol/L, 10(-8) mol/L, 10(-7) mol/L, 10(-6) mol/L) caused a marked increase in cell apoptosis after 48 h incubation time (for 2.50% +/- 0.72%, 6.78% +/- 1.99%, 11.99% +/- 1.58% and 17.93% +/- 4.82%, respectively, P < 0.05). Caspase-3 activity increased and reached a maximal level after 48 h in a linear fashion. The effect of leptin was dose-dependent and time-dependent. Leptin has been demonstrated to induce preadipocyte and adipocyte apoptosis, and today we demonstrate that leptin can induce ADSCs apoptosis, which can contribute to the decrease of adiposity. To our knowledge, this is the first study demonstrating the direct peripheral effect of leptin on ADSCs.