Use of HIF-1alpha mRNA to Promote Pedicle Flap Healing.

Summary/Abstract. Surgical debridement is often used when treating major wounds, and pedicle flaps are a critical component in subsequent surgical reconstructions. Distal portions of the flap require vascular perfusion for overall success of wound repair and reconstruction. Hypoxia-inducible factor-1α (HIF-1α) is an important inducible transcription factor that orchestrates and controls cellular responses to hypoxia when paired with constitutively expressed HIF-1. HIF-1α enhances cell survival in wounds by regulating the expression of over 200 genes, including many angiogenic growth factors responsible for restoration of vascular beds. By combining the concept of increasing HIF-1α in wounds to promote cell survival and revascularization, with contemporary approaches for RNA transduction pioneered in COVID vaccines, our goal is to create a novel therapeutic strategy for enhancing pedicle flap survival. Experiments that support progress toward this goal are proposed in two specific aims: Specific Aim 1A: Quantitation of HIF-1α mRNA and response genes following intradermal injection in Sprague Dawley rats. Based on encouraging preliminary results both in vitro and in vivo, we are developing new versions of our HIF-1 mRNA reagents that are designed to improve activity when delivered in vivo using a proprietary lipid nanoparticle carrier. Rat and porcine versions of our HIF-1 mRNA reagents are being developed for use in pedicle flap assays described in Aims 1B and 2. Specific Aim 1B: In vivo assessment of HIF-1α mRNA therapeutics in a Sprague Dawley rat model of pedicle flap surgery. Findings in Aim 1A will provide preliminary data on best performing reagent structures, dose, and delivery formulations to inform testing in pedicle flap assays in male and female rats. In this aim we will measure HIF-1 expression and downstream gene induction as in Aim1A and add macroscopic monitoring of wound resolution and molecular phenotyping of the wound site using quantitative PCR and immunohistochemistry. Specific Aim 2: In vivo assessment of HIF-1α mRNA therapeutics in a porcine model of pedicle flap surgery. Pigs are valuable preclinical models for testing novel wound healing strategies. The mRNA reagents and formulations that show promise in the rat pedicle flap model in Aim 1B will subsequently be tested in a porcine model of pedicle flap survival and wound healing. Surgical outcomes will be assayed as in Aim 1B to monitor potential translatability of our studies for human clinical applications.