Engineering Injectable Microporous Hydrogels for Diabetic Wound Repair

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PROJECT SUMMARY In this proposal, we aim to engineer a biomaterial scaffold to accelerate diabetic wound closure by improving upon a new sub-class of hydrogel biomaterials we have invented called Microporous Annealed Particle gel or MAP gel. MAP gels are composed of microscopic spherical building blocks made using microfluidic generation and assembled in situ to form a stable MAP scaffold. MAP scaffolds have been shown to improve tissue healing in both skin and brain through a porosity-dependent reduction in wound inflammation and promotion of cell/tissue integration. We are focusing on material improvements to counter three known difficulties for material-based treatment of diabetic wounds: abnormally high immune activity, increased protease concentrations, and diminished new tissue generation. Specifically, we have identified three MAP properties that we can independently modulate for instructive optimization: pore geometry (known immunomodulatory parameter), degradability (premature material degradation results in loss pore-mediated effects), and heterogeneous heparin “micro-islands” (a novel material-based strategy we have developed to improve intra-scaffold angiogenesis). We hypothesize that investigating and optimizing each property individually will accelerate diabetic wound closure and that the optimized properties can be combined synergistically. We will evaluate and optimize each material property using the following characterization workflow: in vitro property quantification (property-dependent), in vitro cell response (survival, proliferation, and migration), in vivo immune response (analysis by FACS), in vivo material degradation (analysis by histology), and in vivo tissue healing/regeneration (analysis by immunohistology). Our studies focus on the diabetic wound environment through use of dermal cell lines in vitro and a diabetic mouse (db/db) splinted wound healing model. Each Aim of our approach isolates an individual material property to simplify the investigation. For example, pore geometry impact is investigated using a single hydrogel formulation and hydrogel formulation impact uses a single pore geometry (constant formulation and pore geometry taken from our successful non-diabetic studies). If successful, this project will provide a better understanding of tissue response to a new class of biomaterial (MAP scaffold) and produce an inexpensive and effective scaffold treatment option for accelerating diabetic wound closure.