Thyroxine restores severely impaired cutaneous re-epithelialisation and angiogenesis in a novel preclinical assay for studying human skin wound healing under "pathological" conditions ex vivo

Low thyroxine serves as an upstream regulator of ecophysiological adaptations in Ansell's mole-rats

Introduction

About 10% of all rodent species have evolved a subterranean way of life, although life in subterranean burrows is associated with harsh environmental conditions that would be lethal to most animals living above ground. Two key adaptations for survival in subterranean habitats are low resting metabolic rate (RMR) and core body temperature (Tb). However, the upstream regulation of these traits was unknown thus far. Previously, we have reported exceptionally low concentrations of the thyroid hormone (TH) thyroxine (T4), and peculiarities in TH regulating mechanisms in two African mole-rat species, the naked mole-rat and the Ansell's mole-rat.

Methods

In the present study, we treated Ansell's mole-rats with T4 for four weeks and analyzed treatment effects on the tissue and whole organism level with focus on metabolism and thermoregulation.

Results

We found RMR to be upregulated by T4 treatment but not to the extent that was expected based on serum T4 concentrations. Our data point towards an extraordinary capability of Ansell's mole-rats to effectively downregulate TH signaling at tissue level despite very high serum TH concentrations, which most likely explains the observed effects on RMR. On the other hand, body weight was decreased in T4-treated animals and Tb was upregulated by T4 treatment. Moreover, we found indications of the hypothalamus-pituitary-adrenal axis potentially influencing the treatment effects.

Conclusion

Taken together, we provide the first experimental evidence that the low serum T4 concentrations of Ansell's mole-rats serve as an upstream regulator of low RMR and Tb. Thus, our study contributes to a better understanding of the ecophysiological evolution of the subterranean lifestyle in African mole-rats.

[Role of neodymium laser in surgery: stimulation of postoperative surgical wounds healing. Results of clinical studies]

OBJECTIVE

To prove the effectiveness of the low-intensity laser radiation application in the treatment of wounds of different origin.

MATERIAL AND METHODS

The clinical study involved 110 persons, divided into 55 subjects in both the study and control groups. The patients of the study group were exposed to the long-wave short-pulse neodymium laser immediately and within 35 days after interventions with a skin incision using it, in a way that wound treated with laser received low-level laser therapy. The control group patients' wounds were treated with standard methods by the means of topical drugs corresponding to the clinical manifestations of the wound process in each particular case. The study was carried out in the hospital of the department of maxillofacial and plastic surgery of the dental complex of the «Russian University of Medicine» from 2019 to 2022, and further conservative treatment was conducted in the department of dermatology and cosmetology of the University Hospital of the Medical Graduate School (Institute) of the RSSU. All wounds were classified into three groups for the convenience of systematization and formation of a generalized treatment protocol for postoperative surgical wounds.

RESULTS

The objectivity and optimality of the chosen by us actions were confirmed in the conducted work. The formed scars were visually assessed on the POSAS scale at the end of the treatment by patients and 4 independent doctors, as well as each scar was visually assessed by four independent doctors and patients. At the end of the study we formed and proposed an algorithm for the treatment of surgical wounds of various origins. The parameters of the Aerolase Neo Light Pod neodymium laser for the treatment of patients with different types of skin wounds were clinically determined. Experimentally proven properties of the Aerolase Neo Light Pod neodymium laser on accelerating the healing process of surgical wounds through photobiomodulation mechanism support their regeneration with the formation of negligible normotrophic scars, as well as reduce the length of patients' treatment in surgical hospitals, as compared to patients receiving standard external drugs.

Requisite instruments for the establishment of three-dimensional epidermal human skin equivalents-A methods review

Human skin equivalents (HSEs) are three-dimensional skin organ culture models raised in vitro. This review gives an overview of common techniques for setting up HSEs. The HSE consists of an artificial dermis and epidermis. 3T3-J2 murine fibroblasts, purchased human fibroblasts or freshly isolated and cultured fibroblasts, together with other components, for example, collagen type I, are used to build the scaffold. Freshly isolated and cultured keratinocytes are seeded on top. It is possible to add other cell types, for example, melanocytes, to the HSE-depending on the research question. After several days and further steps, the 3D skin can be harvested. Additionally, we show possible markers and techniques for evaluation of artificial skin. Furthermore, we provide a comparison of HSEs to human skin organ culture, a model which employs human donor skin. We outline advantages and limitations of both models and discuss future perspectives in using HSEs.

Topical L-thyroxine: The Cinderella among hormones waiting to dance on the floor of dermatological therapy?

Topical hormone therapy with natural or synthetic ligands of nuclear hormone receptors such as glucocorticoids, vitamin D analogues and retinoids has a long and highly successful tradition in dermatology. Yet the dermatological potential of thyroid hormone receptor (TR) agonists has been widely ignored, despite abundant clinical, cell and molecular biology, mouse in vivo, and human skin and hair follicle organ culture data documenting a role of TR-mediated signalling in skin physiology and pathology. Here, we review this evidence, with emphasis on wound healing and hair growth, and specifically highlight the therapeutic potential of repurposing topical L-thyroxine (T4) for selected applications in future dermatological therapy. We underscore the known systemic safety and efficacy profile of T4 in clinical medicine, and the well-documented impact of thyroid hormones on, for example, human epidermal and hair follicle physiology, hair follicle epithelial stem cells and pigmentation, keratin expression, mitochondrial energy metabolism and wound healing. On this background, we argue that short-term topical T4 treatment deserves careful further preclinical and clinical exploration for repurposing as a low-cost, effective and widely available dermatotherapeutic, namely in the management of skin ulcers and telogen effluvium, and that its predictable adverse effects are well-manageable.