Cellular and Molecular Mechanisms of Wound Repair

Acute and chronic wounds are a major clinical burden, with persistent inflammation, impaired fibroblast function, defective angiogenesis, and disordered extracellular matrix deposition. The translational potential of existing in vitro models is limited by their poor durability and physiological relevance. The present paper aims to develop a robust in vitro organotypic model to simulate the early phases of both acute and chronic wounds and to validate it by testing the biocompatibility of clinically available wound dressings. Human fibroblasts and vascular endothelial cell lines were cultured at a ratio of 1:1 for 48 h, either on uncoated tissue culture plastic or on tissue culture plastic coated with a synthetic substrate (PhenoDrive-Y) that biomimics the extracellular matrix and promotes cell organization into tissue-like structures on a 2D plane (i.e., angiogenesis sprouting and fibroblast organization around it). Wound conditions were then created by damaging the formed structures using a conventional scratch procedure and introducing U937 human macrophage cells to the model to simulate either the onset of an acute wound or that of a chronic wound through the simultaneous spiking of the culture with relevant cytokines, i.e., IL-6 and TNF-α. The formation of new tissue-like structures in the scratch area was quantified by the extent of scratch closure after a further 24 h of incubation. Morphological analysis of wound healing was performed by light microscopy, while angiogenesis was assessed by CD31 immunostaining by confocal microscopy. The deposition of components of the extracellular matrix was determined both qualitatively and quantitatively by Picrosirius Red staining for collagen production and by Alcian Blue staining for glycosoaminoglycan synthesis on the adhering cells and their supernatants. Macrophage polarization into either M1 or M2 phenotype was studied by immunostaining with iNOS (M1) and CD206 (M2) antibodies by confocal microscopy. The model was validated by studying the gap closure areas in simulated acute and chronic wound-like conditions when incubated with clinically available wound dressings, N-A Ultra and Kaltostat. PhenoDrive-Y allowed the formation of tissue-like structures on the 2D tissue culture plane as opposed to the formation of cell monolayers on the uncoated tissue culture plastic. Upon mechanical damage, cell migration was significantly different; uncoated control co-cultures achieved complete closure as an indistinct monolayer by 24 h, while the organotypic wound models showed a slower percentage of damage closure. A further delay in the closure of the damaged area was observed when chronic wound-like conditions were simulated. Angiogenesis in chronic wound conditions was considerably impaired compared to the acute conditions. The analysis of the extracellular matrix component synthesis, specifically collagen and polysaccharides, revealed the deposition of dense, organized collagen fibers in the acute wound model, in contrast to the thin, fragmented collagen fibers and intracellular polysaccharides observed under chronic wound-like conditions. This corresponded to a statistically significant increase in the levels of both collagen and polysaccharides detected as soluble molecules in the supernatants. Macrophage polarization showed no statistically significant differences in the acute and chronic wound models, though iNOS did significantly decrease after N-A application in acute and chronic models. However, acute wound-like conditions showed a restoration of the vascularized tissue-like structures after treatment with these types of dressings, albeit through different organizational pathways, whereas only minimal improvement was noted under chronic wound conditions, particularly in the case of the N-A dressing. The organotypic dermis model for the onsets of acute and chronic wounds emerges as a highly versatile tool to understand healing mechanisms in the absence or presence of co-morbidities and to assess the biocompatibility of wound dressings as well as the safety, efficacy and dosage of drugs. Full article

Diabetic wounds exhibit impaired immune function, delayed neutrophils recruitment, and heightened infection risk which compromises early infection control and delays healing. We have demonstrated that topical CCL3 treatment restores neutrophil influx, reduces bacterial infection by ~99%, and accelerates wound healing in diabetic mice. As per Food and Drug Administration (FDA) Guidelines for Investigational New Drug (IND), we conducted a 14-day acute toxicity study in diabetic mice following a single topical administration of CCL3 at effective low dose (1 µg) and high dose (10 µg) per wound. Mice were monitored for clinical signs, body weight, and food intake throughout the study period. On day 14, serum biochemistry (ALT, AST, BUN, creatinine, metabolic markers) and histopathology of major organs (liver, kidney, heart, lungs, spleen) were assessed. CCL3-treated diabetic mice exhibited no adverse clinical effects. Hematological and biochemical parameters remained within normal limits, and histopathological analyses revealed no additional organ injury in CCL3-treated groups compared to diabetic control mice. Intriguingly, CCL3-treated mice showed improved ALT levels and reduced hepatic pathology, suggesting hepatoprotective effects and reduced serum IgG, indicating reduced systemic inflammation. Overall, our study demonstrates that diabetic mice tolerate topical CCL3 at doses up to 10 times the effective therapeutic concentration without evidence of systemic organ toxicity. These findings provide strong preclinical support for the translational development of CCL3 as a novel therapy for diabetic wound care. Full article

Corneal problems, such as delayed and incomplete wound repair, are frequent in diabetes, affecting up to 70% of diabetic patients. In skin, histone deacetylases (HDACs) have been previously found to repress expression of the glycerol channel aquaporin-3 (AQP3), the deficiency of which delays corneal wound healing. We hypothesized that the pan-HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) would improve corneal healing in diabetic mice. Diabetic and normoglycemic C57BL/6J male and female mice were subjected to corneal debridement. Wounds were treated topically with vehicle or SAHA every four hours until they healed. Treatment with SAHA improved wound healing in both normoglycemic and hyperglycemic male mice but, unexpectedly, no changes were detected in female mice. In male mice interleukin-1beta (IL-1β) and tumor necrosis factor (TNF) were significantly increased in diabetic corneas, and SAHA reduced their expression, returning IL-1β and TNF to levels comparable to those in normoglycemic mice regardless of treatment. In normoglycemic male mice, AQP3 levels were not changed in the cornea with SAHA treatment but the expression of AQP3 was increased in the wound’s edge relative to the rest of the cornea. In vitro SAHA treatment of human corneal epithelial cells (HCECs) significantly increased protein expression of AQP3, important for corneal wound healing, but had no effect on ROS production. In conclusion, treatment with SAHA improved corneal wound healing, not only in male mice with diabetes and delayed wound healing but also in normoglycemic male mice; therefore, SAHA could potentially be repurposed as a topical treatment clinically to improve corneal wound healing. Full article

Chronic wound healing is a complex and tightly regulated process requiring coordinated epithelial and stromal regeneration. Photobiomodulation (PBM) using low-level red light-emitting diode (LED) therapy has emerged as a non-invasive approach to enhancing skin repair. In this study, we evaluated the therapeutic efficacy of a pulsed, multi-wavelength LED system on full-thickness excisional wound healing in a normal murine model. Daily LED treatment significantly accelerated wound closure, promoted re-epithelialization, and improved dermal architecture. Histological and immunohistochemical analyses revealed enhanced epidermal stratification, reduced inflammation, and improved collagen organization. Molecular profiling demonstrated increased expression of proliferation marker Ki67, keratins CK14 and CK17, and extracellular matrix-related genes including MMPs, Col1a1, and Col3a1. In vitro assays using HaCaT keratinocytes showed accelerated scratch wound closure and cytoskeletal remodeling following PBM exposure. These findings suggest that pulsed PBM promotes coordinated epithelial regeneration and matrix remodeling, highlighting its potential as a tunable and effective therapeutic modality for accelerating cutaneous wound healing under physiological conditions. Full article

(1) Background: Wound healing is a highly coordinated process encompassing hemostasis, inflammation, angiogenesis, keratinocyte migration, collagen deposition, and extracellular matrix remodeling. Successful repair also requires adequate nutrient and oxygen delivery through a well-developed vascular supply. Disruption of these processes can occur through aberrations in diverse biological pathways, including extracellular matrix organization, cellular adhesions, angiogenesis, and immune regulation. (2) Methods: We reviewed mechanisms of impaired tissue repair in monogenic disorders by focusing on three categories—connective tissue, hematological/immunological, and aging-related disorders—to illustrate how single-gene defects disrupt inflammation, cellular proliferation, and matrix remodeling. Additionally, we reviewed various polygenic disorders—chronic kidney disease, diabetes mellitus, hypertension, and obesity—to contrast complex multifactorial pathologies with single-gene defects. (3) Results: This review establishes that genetic impediments, despite their distinct etiologies, monogenic and polygenic disorders share critical downstream failures in the wound healing cascade. While monogenic diseases illustrate direct causal links between specific protein deficits and repair failure, polygenic diseases demonstrate how multifactorial stressors overwhelm the body’s regenerative capacity. (4) Conclusions: This review synthesizes current evidence on both monogenic diseases and polygenic contributions to impaired wound healing. These findings highlight that genetic susceptibility is a decisive factor in the ability to restore tissue homeostasis. This underscores the profound impact of genetic background on the efficacy of hemostasis, inflammation, and remodeling. Full article

Wound repair preserves tissue integrity through four overlapping phases—hemostasis, inflammation, proliferation, and remodeling—coordinated by platelets, neutrophils, macrophages, fibroblasts, keratinocytes, endothelial cells, and stem/progenitor cells acting with growth factors, chemokines, extracellular matrix, and intracellular signaling. Disruption of these programs results in chronic non-healing wounds or fibrotic scarring. Recent work delineates microbial influences, epigenetic and transcriptomic regulation, and cellular heterogeneity resolved by single-cell and spatial omics. Concurrent advances in biomaterials, engineered scaffolds, stem cell-derived products, and genome-targeted approaches are enabling mechanism-based therapies. Persistent challenges include wound heterogeneity, systemic modifiers such as diabetes and aging, and safe, effective delivery of biologics. This review summarizes cellular and molecular mechanisms of cutaneous repair, outlines deviations that underlie pathological healing, and evaluates emerging concepts and translational strategies. Integrating classical models with contemporary insights supports the development of precision wound medicine and personalized interventions to improve outcomes and quality of life. Full article