Improved management of wound healing represents a significant unmet need in the United States, particularly in individuals with obesity and type 2 diabetes. In addition, the molecular events that lead to insulin resistance remain poorly understood. Recent studies suggest that ganglioside GM3, a sialylated membrane glycosphingolipid, is a critical mediator of insulin resistance, as evidenced by the reversal of insulin resistance following ganglioside depletion in cultured adipocytes and diabetic mouse models. We have discovered that GM3 accumulates in keratinocyte (KC) membranes in diabetic mice, and that depletion of GM3 reverses their wound healing defect. We propose that genetic inhibition of ganglioside synthesis through the use of a novel nanotechnology approach will reverse impaired wound healing in KCs under high glucose conditions and in diabetic mice. The long-term goals of this project are to apply gene-suppressing topically-applied nanoparticles that block ganglioside biosynthesis as a new means to address the impaired wound healing in diabetics and to better understand how gangliosides impact KC proliferation and motility. We will use our unique oligonucleotide-conjugated gold nanoparticles (Au NPs), single agents that show universal uptake in cells and highly efficient gene knockdown. We will first evaluate the efficacy and safety of topically-applied GM3 synthase siRNA-Au NPs, which deplete gangliosides, in accelerating healing in diabetic mouse models. Next, we will determine how gangliosides impact KC motility. Using DNA- and siRNA-Au NPs to increase and deplete ganglioside GM3, respectively, we will assess KC proliferation and wound closure in vitro. We will then examine the effect of gangliosides on insulin receptor (IR), insulin-like growth factor-1 receptor-integrin (IGF- 1R), and epidermal growth factor receptor (EGFR) activation, all of which impact KC wound healing. Finally, we will evaluate the impact of GM3 depletion on glucose-induced insulin resistance. These studies will increase our understanding of the role of glycosphingolipids in wound healing. In addition, reversal of the wound healing defect in obese diabetic mice by topical administration of our nanoparticle-conjugated nucleic acid inhibitors of ganglioside synthesis will be an innovative means to promote wound healing in chronic wounds. These studies promise to have great impact in the treatment of wounds in humans, particularly in individuals with insulin-resistant diabetes.
Ganglioside GM3 has recently been linked to insulin resistance, and we have shown that ganglioside depletion reverses the wound healing defect in keratinocytes (KCs) and diabetic mice. Using polyvalent oligonucleotide- conjugated gold nanoparticles, we will modulate ganglioside expression and assess how ganglioside depletion accelerates KC migration and proliferation. We will also test the efficacy of topical application of siRNA-Au NPs in depleting gangliosides, thereby reversing the impaired wound healing of diabetic mice and providing the basis for therapeutic trials using nanotechnology to correct the wound healing defect in insulin-resistant diabetes.
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