Abstract 212: Genetically Modified Mesenchymal Stem Cells Help Reduce Inflammation and Glucose-Mediated Insulin Response in Obese Diabetic Mouse Models

Abstract

MSCs are multipotent cells that differentiate into fat, muscle, bone and cartilage. High Glucose (HG) exposure of bone marrow derived MSCs leads to: increased ROS accumulation both in cytosol and mitochondria ( analysed by FACS using Mitosox Red dye) and increased intra-cellular lipid droplet accumulation. We hypothesized that intra-cellular antioxidant up-regulation specifically mitochondrial (super-oxide dismutase-2), may help reduce superoxide accumulation in mitochondria which will subsequently help reduce fat droplet accumulation and associated cellular inflammation. We exposed hMSCs to HG (25mM) and normal glucose (NG, 5.5 mM) and interrogated mitochondrial superoxide accumulation and cellular oxygen consumption rate (OCR using Seahorse) and interrogated response to mitochondrial complex I-IV 4 substrate addition. We used AdSOD2 to up-regulate SOD2 prior to HG exposure. HG exposure increased TNF α (Tumor Necrosis Factor, 4 fold) and IL6 (interleukin6, 6-fold) mRNA and increased lipid accumulation (2.5 fold) and led to impaired OCR on SeaHorse and impaired Mitochondrial Complex 1. With prior SOD2 upregulation in MSCs, TNF α and IL6 mRNA expression was reduced in HG and improved Complex-1 function. Next we delivered the SOD2 upregulated MSC intra-peritoneally to obese diabetic (db/db) mice. We confirmed homing-in of eGFP labeled MSC, delivered IP, to different fat pockets. The mice that received MSC-SOD2 (experimental) showed reduced adipocyte and systemic inflammation (IL6 and TNF alpha levels) compared the mice that received MSC-Null (control). Interestingly the experimental group showed consistent reduction in fat mass (Echo-MRI), local adipocyte inflammation, systemic inflammation in serum and marked improvement in glucose tolerance tests (GTT). We conclude that local delivery of mitochondrial superoxide dismutase using stem cells as a gene delivery vehicle reduces inflammation and glucose tolerance tests in vivo. We plan to carry out further glucose clamp studies to consolidate our findings. In conclusion local rather than systemic up-regulation of a mitochondrial anti-oxidant helps in reducing local and systemic inflammation, total fat mass and improves glucose mediated insulin response in obese diabetic mouse models.