A Novel Mouse Model for Investigating the Effects of Gender-affirming Hormone Therapy on Surgical Healing

Abstract

Summary: Wound healing problems are a major cause of morbidity for gender-affirming surgery (GAS) patients. Prior studies have shown sex differences in wound healing may exist. We hypothesized exogenous testosterone supplementation may impair post-GAS wound healing and developed a model to investigate this phenomenon. Mice were randomized by hormone regimen and gonadectomy (OVX). Gonadectomy or sham occurred on day 0 and mice were assigned to no testosterone (-T), mono- or bi-weekly (T/2T) testosterone groups. Dorsal splinted wounding occurred on day 14 and harvest on day 21. Serum testosterone levels were quantified with mass spectrometry. Tissue underwent analysis with planimetry, qPCR, ELISA, and immunofluorescence. Mean testosterone trough levels for bi-weekly regimen were higher compared to mono-weekly (397 versus 272 ng/dL; P = 0.027). At POD5, 2T injections led to 24.9% and 24.7% increases in mean wound size relative to SHAM and OVX/-T, respectively (P = 0.004; 0.001). Wounds in OVX/+2T mice demonstrated increased gene expression for inflammatory cytokines and macrophage marker F4/80 (P < 0.05). ELISA confirmed elevated wound TNFα levels (P < 0.05). Quantitative multiplex immunofluorescence with F4/80/NOS2/ARG1 showed significant increases in macrophage prevalence in OVX/+2T (P < 0.05). We developed a novel model of GAS hormonal milieu to study effects of exogenous testosterone on wound healing. Optimized twice-weekly dosing yielded serum levels comparable to clinical therapy. We showed exogenous testosterone administered to XX/OVX mice significantly impairs wound healing. A hyperinflammatory wound environment results in increased macrophage proliferation and elevated cytokines. Future efforts are directed toward mechanistic investigation and clinical validation.

Testosterone Restores Body Composition, Bone Mass, and Bone Strength Following Early Puberty Suppression in a Mouse Model Mimicking the Clinical Strategy in Trans Boys

“…In recent years, a plethora of rodent models have been developed to study the impact of gender-affirming therapy on a variety of outcomes. (24)(25)(26)(27)(28) The vast majority of these studies, however, mimicked the clinical approach in transgender adults. As such, those models were restricted to GAH administration and did not involve puberty suppression to avoid or halt appearance incongruent development in transgender youth.…”

Androgenic Steroids Induce Pathologic Scarring in a Preclinical Swine Model Via Dysfunctional Extracellular Matrix Deposition

“…The testosterone regimen was based on our lab’s previous small animal models as well as work conducted by Kothmann et al 11,17 Testosterone cypionate (West-Ward Pharmaceuticals Eatontown, NJ, USA) 200mg/ml was diluted with pharmaceutical-grade sesame oil (Sigma-Aldrich, St. Louis, MO, USA) to reach a final concentration of 100mg/ml. Four swine (two XX and two XY) received biweekly 1mg/kg/dose testosterone injections while the remainder received placebo sesame oil.…”

“…Despite this, while work has been published about the impact of testosterone on wound healing in murine models little is currently known about the impact of exogenous testosterone on scar formation. [11][12][13][14] In classic models of scarring, sex hormones (testosterone and estradiol) are not modulators of this process. However, over years of surgeries on patients on exogenous T, we observed slower WH and worse scarring, prompting our hypothesis that hormones were significant modulators of wound repair.…”

“…Despite this, while work has been published about the impact of testosterone on wound healing in murine models little is currently known about the impact of exogenous testosterone on scar formation. 11–14…”

“…Our team also previously developed a model of the GAS hormonal milieu and studied the effects of exogenous testosterone on cutaneous wound healing (WH) in mice, finding that T significantly impairs WH. 11 However, there are significant limitations in small animal models to capture translationally relevant differences in scarring due to well-established histological skin differences between rodents and humans. 16 We therefore sought to develop a GAS hormonal milieu model in swine, a more robust option for modeling human scarring, and use this model to test our hypothesis that exogenous testosterone therapy alters scarring.…”