Background

Fat derived mesenchymal stromal cells (MSCs) are multipotent cells that can differentiate into bone, cartilage, muscle and fat, depending on the regenerative need. Endothelial cell dysfunction (ECD) states such as prediabetes and diabetes appear to increase adipogenesis whereas exercise, known to improveECD. Therefore, proper endothelial cell function may play a crucial role in preventing adipogenesis . Here, we investigated if endothelium derived factors paracrine properties present in endothelial conditioned media (ECM) can affect adipose tissue derived MSC differentiation in an adipogenic (obesinogenic) environment. We choose adipogenic media (Lonza Inc) to mimic a clinical scenario of dyslipidemia and insulin resistance such as obesity, prediabetes or diabetes.

Methods

In vitro, commercially obtained mid passage (8 to 9) human MSCs were exposed to adipogenic media (from Lonza) and ECM, (obtained from culturing mature human endothelial cells, for 48 hours, HUVECs) was concentrated, 40 fold and addedat 1:10 ratio per volume (repeated n=3). MSC differentiation was monitored by mRNA expression of associated pathways genes and adipogenesis was further assessed by oil-red-O staining of lipid vacuoles.

Results

Reduced expression of adipogenic genes such as PL1N, FABP4, CEBPA and PPARG (24.6, 13.3, 9.8, 4.2 fold, p= 0.00001, 0.02, 0.00001, 0.0001 respectively). We concomitantly observed significant increase in expression of bone formation markers RUNX2 and BMP2 (1.5, 1.3 fold, p=0.01, 0.01 respectively). We also noted up-regulation of endothelial genes such as VEGF and KDR (1.6 and 2.3 fold, respectively). Oil-red-o staining showed reduced lipid droplets with ECM addition.

Conclusions

We conclude that addition of ECM reduces adipogenesis of mid-passage fat derived MSCs while augmenting bone formation markers. These results indicate a cross-talk between endothelial function, adipose tissue precursor differentiation, fat and bone formation. Studies are underway to identify factors present in ECM