Browsing by Author "Montgomery, Jade"

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    Building a Better Scar: Re-engineering Extracellular Matrix Structure in Dermal Scars
    Montgomery, Jade (Virginia Tech, 2020-01-27)
    Introduction Cutaneous scars represent a common surgical complication, yet no effective drug therapy for scar treatment currently exists despite huge patient and physician demand. A connexin 43 (Cx43) carboxyl terminus (CT) mimetic peptide, alpha Connexin Carboxy-Terminus 1 (αCT1), has demonstrated efficacy in improving long-term scar appearance in pre-clinical and clinical trials. However, current understanding of the mechanism-of-action by which αCT1 improves long-term scar appearance with early intervention treatment is not well understood. Methods In vivo: Scar biopsies from 1) human, 2) Sprague-Dawley rat, and 3) IAF Hairless guinea pig trials of αCT1 were examined for collagen matrix structure at 4 weeks (all models), and 2 and 6 weeks (rat and guinea pig models only). Collagen matrix variables examined included local disorganization of the fibers, a variable that is higher in unwounded skin compared to scar tissue, and density of the fibers, which is higher in scar tissue but can also be used as an early temporal marker of the rate of healing. In vitro: Primary murine dermal fibroblasts were isolated from the whole dermis of 3-4 week old transgenic mice expressing collagen 1(α2) GFP-tpz. Cells were sorted for expression via FACS and plated on prealigned collagen substrate for 7 days under conditions favorable to generating extracellular matrix. Results: All in vivo scar biopsies demonstrated some level of altered collagen matrix structure with αCT1 treatment. Treated scars had higher local disorganization of the collagen fibers within the wound, and an increase in collagen matrix density compared to control at certain earlier timepoints that tended to decrease or disappear at later timepoints. The IAF Hairless guinea pig, a novel splinted wound healing model presented herein, was found to closely replicate the human dermal collagen profile and changes in collagen profile spurred by αCT1, significantly outperforming the traditional rat model. Primary dermal murine fibroblasts treated in vitro with αCT1 significantly increased synthesis of procollagen 1, the precursor of collagen 1 necessary for constructing the extracellular matrix, suggesting that at least part of the reason for higher collagen density at early in vivo timepoints is due to increased collagen synthesis by fibroblasts. Conclusion: αCT1 treatment in the early stages of wound healing prompts individual fibroblasts to increase their output of collagen and create a more disorganized early collagen matrix. These early changes potentially spur the long-term scar appearance improvements seen in clinical trials, and provide a basis for future work to discover the cellular pathways to alter in order to improve wound healing and cutaneous scarring outcomes.
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    The connexin 43 carboxyl terminal mimetic peptide αCT1 prompts differentiation of a collagen scar matrix in humans resembling unwounded skin
    Montgomery, Jade; Richardson, William J.; Marsh, Spencer; Rhett, J. Matthew; Bustos, Francis; Degen, Katherine; Ghatnekar, Gautam S.; Grek, Christina L.; Jourdan, L. Jane; Holmes, Jeffrey W.; Gourdie, Robert G. (Wiley, 2021-07-10)
    Phase II clinical trials have reported that acute treatment of surgical skin wounds with the therapeutic peptide alpha Connexin Carboxy-Terminus 1 (αCT1) improves cutaneous scar appearance by 47% 9-month postsurgery. While Cx43 and ZO-1 have been identified as molecular targets of αCT1, the mode-of-action of the peptide in scar mitigation at cellular and tissue levels remains to be further characterized. Scar histoarchitecture in αCT1 and vehicle-control treated skin wounds within the same patient were compared using biopsies from a Phase I clinical trial at 29-day postwounding. The sole effect on scar structure of a range of epidermal and dermal variables examined was that αCT1-treated scars had less alignment of collagen fibers relative to control wounds—a characteristic that resembles unwounded skin. The with-in subject effect of αCT1 on scar collagen order observed in Phase I testing in humans was recapitulated in Sprague–Dawley rats and the IAF hairless guinea pig. Transient increase in histologic collagen density in response to αCT1 was also observed in both animal models. Mouse NIH 3T3 fibroblasts and primary human dermal fibroblasts treated with αCT1 in vitro showed more rapid closure in scratch wound assays, with individual cells showing decreased directionality in movement. An agent-based computational model parameterized with fibroblast motility data predicted collagen alignments in simulated scars consistent with that observed experimentally in human and the animal models. In conclusion, αCT1 prompts decreased directionality of fibroblast movement and the generation of a 3D collagen matrix postwounding that is similar to unwounded skin—changes that correlate with long-term improvement in scar appearance.
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    Connexin 43-Based Therapeutics for Dermal Wound Healing
    Montgomery, Jade; Ghatnekar, Gautam S.; Grek, Christina L.; Moyer, Kurtis E.; Gourdie, Robert G. (MDPI, 2018-06-15)
    The most ubiquitous gap junction protein within the body, connexin 43 (Cx43), is a target of interest for modulating the dermal wound healing response. Observational studies found associations between Cx43 at the wound edge and poor healing response, and subsequent studies utilizing local knockdown of Cx43 found improvements in wound closure rate and final scar appearance. Further preclinical work conducted using Cx43-based peptide therapeutics, including alpha connexin carboxyl terminus 1 (αCT1), a peptide mimetic of the Cx43 carboxyl terminus, reported similar improvements in wound healing and scar formation. Clinical trials and further study into the mode of action have since been conducted on αCT1, and Phase III testing for treatment of diabetic foot ulcers is currently underway. Therapeutics targeting connexin activity show promise in beneficially modulating the human body’s natural healing response for improved patient outcomes across a variety of injuries.