Topical α-Gal Nanoparticles Enhance Wound Healing in Radiated Skin

Abstract

Surgery within radiated tissue is associated with increased complication rates. It is hypothesized that impaired wound healing may result from aberrant inflammatory responses that occur in previously radiated tissues. Previous work has demonstrated that the topical application of naturally occurring antigen α-gal (Galα1-3Galβ1-(3)4GlcNAc-R) nanoparticles (AGNs) within wounds accelerates macrophage recruitment and subsequent healing in both normal and diabetic wounds. Herein, we hypothesize that application of this antigen would similarly enhance wound healing in irradiated tissues. Methods: To simulate human physiology, α-1,3-galactosyltransferase knockout (KO) mice were exposed to the antigen to produce anti-α-gal antibodies (anti-Gal). Ten days prior to wounding, the dorsal skin was irradiated with 1 session of 40 Gy. Bilateral dorsal 6-mm splinted full-thickness wounds were created within the radiated skin and treated with 50 µL of AGNs (50 mg/mL) immediately after wounding and again on postoperative day 1. A control KO group underwent similar irradiation and wounding protocols but was treated with phosphate-buffered saline (PBS) vehicle. Wild-type (WT) mice, which do not produce anti-Gal, went through the same irradiation and wounding. Results: Histologic analysis demonstrated enhanced epithelial migration in the radiated/AGN-treated KO wounds, which was significantly elevated in comparison to radiated/PBS-treated KO wounds beginning by day 15 and continuing until the end of the study (p < 0.01). In WT mice, treatment with AGNs showed no effect on epithelial migration. Conclusions: Topical application of AGNs onto irradiated wounds significantly ameliorates the delayed wound healing classically seen in radiated skin and results in faster wound closure with only transient application.

Transdermal deferoxamine administration improves excisional wound healing in chronically irradiated murine skin

“…Irradiated wounds that failed to close by POD21 were harvested the following day and were considered "non-healing". This determination was based on prior studies and our own pilot wounding studies, which indicated that healing would no longer progress after POD21 as re-epithelialization had occurred but wounds were too fragile, preventing complete healing and full closure [10]. Harvested wounds were fixed in 10% neutral buffered formalin overnight, embedded in paraffin, and then sectioned into 8 μM thick sections.…”

“…This is notable as dermal hypovascularity, a hallmark of RIF, is responsible for reduced nutrient supply and is likely a key contributor to the impaired wound healing seen in irradiated skin [35]. Prior murine studies have demonstrated a similar correlation between increased angiogenesis and improved healing outcomes in irradiated wounds [10,12]. Clinically, good perfusion is a sine qua non for wound healing.…”

“…Irradiated fibroblasts and myofibroblasts demonstrate impaired collagen deposition and contractile force generation in the acute wound healing phases, respectively. Reduced keratinocyte proliferation results in delayed epithelial migration and hyperplasia [10]. Granulation tissue formation is also delayed due to impaired collagen deposition resulting in significantly reduced collagen density and weaker breaking strength in the healing wound bed [11].…”

Biosynthesis of α-Gal Epitopes (Galα1-3Galβ1-4GlcNAc-R) and Their Unique Potential in Future α-Gal Therapies

“…The repair of wounds by α-gal nanoparticles was found to be potent enough to also occur in diabetic mice with chronic wounds which do not heal without such treatment (Galili, 2017;Kaymakcalan et al, 2020). This potent healing effect was further demonstrated in mouse radiation wounds in which topical application of α-gal nanoparticles resulted in faster wound healing than the delayed wound healing usually seen in irradiated skin (Samadi et al, 2021). The accelerated wound healing by α-gal nanoparticles was validated in the large experimental animal model of GT-KO pigs (Hurwitz et al, 2012).…”

“…Wound and burn healing by α-gal nanoparticles —the effects of α-gal therapy by α-gal nanoparticles were studied on skin injuries ( Galili et al, 2010 ; Wigglesworth et al, 2011 ; Kaymakcalan et al, 2020 ; Galili, 2017 ; Kaymakcalan et al, 2018 ; Samadi et al, 2021 ; Hurwitz et al, 2012 ). Application of α-gal nanoparticles to full-thickness wounds or burns of anti-Gal–producing GT-KO mice decreased the healing time by ∼50% in comparison to wound healing time in untreated GT-KO mice.…”