(719g) Polyvalent Histamine/Histidine Derivatives of Hyaluronic Acid for Accelerating Wound Healing

Histamine, as one of the mediators released from mast cells, has been widely studied for its role in wound healing. It was suggested that exogenous histamine promoted angiogenesis and recruitment of macrophages by upregulating basic fibroblast growth factor (bFGF) levels in wounds, and histamine stimulated fibroblast proliferation, production of αSMA, and collagen synthesis. We have synthesized and characterized low, medium, high molecular weight hyaluronic acid conjugated with histamine or histidine biopolymers and evaluated for acute wound healing in mice and enhancing innate immune responses in macrophages. In our preliminary studies, we found that delivery of high molecular weight hyaluronic acid conjugated histamine (HAA) and histidine (HAD) enhanced the closure of full-thickness excisional wounds in BALB/c mice. We observed that high molecular weight hyaluronic acid-histidine (HAD) polymer enhanced the activation of NF-κB in J774 dual macrophages, which indicates the activation of the innate immune response induced by this material. We evaluated TNF-alpha, IL-6, IL-1beta cytokine release to understand the inflammatory response of these polymers in J774 dual macrophages. We also evaluated the intracellular calcium release in keratinocytes with HAA and HAD polymers and studied the calcium influx inhibition with histamine receptor antagonists’ pre-treatment. We observed selective inhibition of calcium signaling with histamine receptor 1 (HRH1) antagonist, Diphenhydramine. We also investigated the uptake of these polymers in keratinocytes and macrophages by conjugating with a dye, rhodamine. Our findings convincingly demonstrated that histamine or histidine conjugated hyaluronic acid biomaterials resulted in infiltration of pro-resolution macrophages and neutrophils in the wound bed to speed up wound healing in mice, which was significant compared with control groups. We hypothesize that these polymers will induce histamine receptor targeted delivery, specific immune response against antigens with limited toxicity. Further investigations are underway for evaluating the histamine receptor -mediated mechanistic pathways and adjuvant efficacy of these polymers using in vitro and in vivo mouse models.