We aimed to characterize the physiological effects of up regulating endothelial heme oxygenase‐1 (HO‐1) on adipogenesis in human mesenchymal stem cells (MSCs). Microvessel endothelial cells (HMEC‐1) were cultured along with a lentiviral (lenti) construct expressing human HO‐1 under the control of endothelium specific promoter vascular endothelium cadherin heme oxygenase (VECAD‐HO‐1) and Lenti‐VECAD‐GFP used as the control. In complementary experiments HMEC‐1 cells were cultured in the presence or absence of tin‐mesoporphrin (5 μM). Conditioned media (CM) was harvested and tested at 5%, 10% and 20%. The 10% CM from HMEC cells was used for ideal effect, along with adipogenic media, to measure paracrine effect on adipogenesis in MSCs. The MSCs exposed to CM from VECAD‐HO‐1 transfected cells demonstrated reduced (10.2 ± 1 at 490nm) adipogenesis (lipid droplets) as compared to MSCs exposed to CM from Lenti‐VECAD‐GFP cells (17.0±2, p>;0.05). CM from HMEC‐1 cells treated with inhibitor of HO‐1 activity promoted higher adipogenesis with increased adipocyte hypertrophy as opposed to HMEC‐1 treated activity transfected with the VECAD‐GFP control ( 24.5±1, p<0.01). These observations suggest that EC under stressed conditions releases a negative regulator as seen in VECAD‐HO‐1 in presence of HO‐1 inhibitor and increases adipocyte dysfunction.

Introduction: Obesity or high fat diet (HF) are risk factors for the development of hypertension. We examined the hypothesis that targeting the vascular system with human heme oxygenase -1 (HO-1) may attenuate both vascular and adipocyte dysfunction in vivo and in vitro. Methods: Lentivirus (Lenti) construct expressing human HO-1 under the control of endothelium specific promoters VE-cadherin (VECAD-HO-1) and VECAD −GFP (control) were used to treat mice, using a bolus injection into the renal artery, and kept on a high fat diet for 26 weeks. Human HO-1 gene expression was sustained for 9 months. For in vitro studies, human EC were cultured with Lenti- VECAD-HO-1 and added to Lenti-VECAD-GFP or control. The conditioned media (CM) from ECs was harvested and 10% CM was added to adipogenic media to measure paracrine effect on adipogenesis in human Mesenchymal Stem Cells (MSCs) derived adipocytes. Signaling molecules were measured by western blot. Results: Lentiviral transduction with VECAD-HO-1 construct attenuated the increase in blood pressure (from 149.9 ± 2.4 to 118 ± 2.0 mmHg, p<0.01) and prevented body weight gain by 39% (p<0.05) in obese mice and increased plasma adiponectin (from 2.9 ± 0.2 to 6.5 ± 0.1 μg/ml, p<0.05). CM derived from EC lenti HO-1 decreased adipogenesis compared to control (from 17.0 ± 0.2 to 10.2 ± 0.1, p<0.05) and resulted in an increase of β-catenin and Wnt but a decrease in PPARγ (p<0.05). These beneficial effects were reversed by treating the cell with SnMP, an inhibitor of HO activity (p<0.01). EC-HO-1 increased angiopoietin-1 (ANG-1), vascular endothelial growth factor A (VEGF), and platelet derived growth factor (PDGF)-AA,−BB (p<0.05). The addition of ANG-1 to adipogenic media resulted in the inhibition of adipogenesis (8.1 ± 0.1, p<0.01). Conclusion: Targeting HO-1 to ECs resulted in the attenuation of blood pressure and the prevention of body weight gain resulting in increased ANG-1, PDGF, and VGEF levels and the reprogramming of MSCs derived adipocytes to produce healthy and smaller adipocytes with the release of adiponectin.