The effect of pulsed electromagnetic fields on secondary skin wound healing: an experimental study

A variety of pulsed electromagnetic fields (PEMFs) have already been experimentally used, in an effort to promote wound healing. The aim of the present study was to investigate the effects of short duration PEMF on secondary healing of full thickness skin wounds in a rat model. Full thickness skin wounds, 2 by 2 cm, were surgically inflicted in two groups of male Wistar rats, 24 animals each. In the first group (experimental group - EG), the animals were placed and immobilized in a special constructed cage. Then the animals were exposed to a short duration PEMF for 20 min daily. In the second group (control group - CG), the animals were also placed and immobilized in the same cage for the same time, but not exposed to PEMF. On days 3, 6, 9, 12, 18, and 22, following the infliction of skin wounds, the size and healing progress of each wound were recorded and evaluated by means of planimetry and histological examination. According to our findings with the planimetry, there was a statistically significant acceleration of the healing rate for the first 9 days in EG, whereas a qualitative improvement of healing progress was identified by histological examination at all time points, compared to the control group.     

Fetal wound healing: a biochemical study of scarless healing

Human fetal surgery is being successfully performed today in a small number of highly selected patients for conditions that may lead to irreversible damage to the fetus and threaten the viability of the newborn. Following surgical repair, fetal wounds heal without scarring. This study was initiated to characterize fetal wounds both histologically and biochemically. Gore-Tex tubing was implanted into the subcutaneous tissue of the back of fetal, newborn, and adult New Zealand white rabbits. Light microscopic examination of healed wounds revealed no evidence of scar formation. Electron microscopy demonstrated a striated fibrillar structure suggestive of collagen within the lumen of the Gore-Tex tubing implants. Amino acid analysis (sensitivity 40 pmol) confirmed the presence of hydroxylysine and hydroxyproline within the Gore-Tex wound chambers indicating the presence of collagen in fetal wounds. The small amount of collagen precluded the typing of the collagen using cyanogen bromide peptide analysis. The absence of scarring and the small amounts of detectable collagen suggest a high degree of reorganization of the connective tissues involved in repair. The fetal wound matrix is rich in hyaluronic acid. Topical hyaluronic acid has been associated experimentally with a reduced amount of scarring in postnatal wound healing. Hyaluronic acid extracted from human skin and scar tissue is associated with collagen and other proteins. We propose that a hyaluronic acid-collagen-protein complex may play a role in fetal wound healing.     

Complex evaluation of wound healing process by a deep wound rat model with implanted polychlorvinyl camera

A simultaneous study of wound proteolytic activity and morphological picture of the first stages of wound healing on rat deep wound model has been shown. The process of wound healing can be evaluated by dynamics of matrix metalloproteinase activities in wound fluid. Changes in activities of different matrix metalloproteinases correlate with different stages of healing. Implantation of polychlorvinyl camera in the wound makes it possible to obtain the volume of wound fluid sufficient for a complex evaluation of healing at the initial stages of wound process.     

Nutrition and wound healing: an update

Nutrition has always been noted to be one of the major influences on the successful outcome of wound healing. The exuberant cellular and biochemical events that constitute the wound-healing cascade require energy, amino acids, oxygen, metals, trace minerals, and vitamins for successful completion. Many nutritional deficiencies impact on wound healing by impeding fibroblast proliferation, collagen synthesis, and epithelialization. There are also nutrients that can enhance wound-healing responses. It is imperative for physicians to obtain a complete nutritional history and consider nutritional intervention as a means of affecting the course of healing. This review examines many of the advances that have occurred in understanding nutrition/wound interactions.     

Biodegradable microparticles with immobilized peptide for wound healing

Thrombin receptor agonist peptide (TRAP-6) may be successfully used instead of thrombin to stimulate regeneration of damaged tissues. Thrombin application is limited by its high price, instability, and proin-flammatory effect at high concentrations. Immobilization of TRAP-6 into a matrix based on lactic and glycolic acid copolymer (PLGA) prevents its destruction by peptidases located in the wound and can also provide controlled release of the peptide. PLGA microparticles with the immobilized peptide were prepared by the double emulgation method. The presence of the immobilized peptide increased the porosity of the microparticle surface detected by scanning electron microscopy. Kinetics of the TRAP-6 release was characterized by a dramatic increase in its concentration in buffer solution (pH 7.5) during the first 2 h after the experiment beginning, and the complete release of the peptide after 20 h. An investigation of TRAP-6 destruction by scanning electron microscopy revealed the increase in the microparticle size and surface porosity already after one day of incubation, and the destroyed microparticles were aggregated by the seventh day of the incubation. Thus, peptide immobilization into PLGA microparticles may be employed for elaboration of a prolonged action preparation with the controlled release of the active agent (peptide).     

Regeneration: The ultimate example of wound healing

The outcome of wound repair in mammals is often characterized by fibrotic scaring. Vertebrates such as zebrafish, frogs, and salamanders not only heal scarlessly, but also can regenerate lost appendages. Decades of study on the process of animal regeneration has produced key insights into the mechanisms of how complex tissue is restored. By examining our current knowledge of regeneration, we can draw parallels with mammalian wound healing to identify the molecular determinants that produce such differing outcomes.     

Regulation of wound healing and organ fibrosis by toll-like receptors

Chronic injury often triggers maladaptive wound healing responses leading to the development of tissue fibrosis and subsequent organ malfunction. Inflammation is a key component of the wound healing process and promotes the development of organ fibrosis. Here, we review the contribution of Toll-like receptors (TLRs) to wound healing with a particular focus on their role in liver, lung, kidney, skin and myocardial fibrosis. We discuss the role of TLRs on distinct cell populations that participate in the repair process following tissue injury, and the contribution of exogenous and endogenous TLR ligands to the wound healing response. Systemic review of the literature shows that TLRs promote tissue repair and fibrosis in many settings, albeit with profound differences between organs. In particular, TLRs exert a pronounced effect on fibrosis in organs with higher exposure to bacterial TLR ligands, such as the liver. Targeting TLR signaling at the ligand or receptor level may represent a novel strategy for the prevention of maladaptive wound healing and fibrosis in chronically injured organs. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.     

Metalloproteinases and their inhibitors: regulators of wound healing

Wound healing is a dynamic process that involves a coordinated response of many cell types representing distinct tissue compartments and is fundamentally similar among tissue types. Among the many gene products that are essential for restoration of normal tissue architecture, several members of the matrix metalloproteinase (MMP) family function as positive and, at times, negative regulators of repair processes. MMPs were initially thought to only function in the resolution phase of wound healing, particularly during scar resorption; however, recent evidence suggests that they also influence other wound-healing responses, such as inflammation and re-epithelialization. In this review, we discuss what is currently known about the function of MMPs in wound healing and will provide suggestions for future research directions.     

Scarless fetal wound healing: a basic science review

SUMMARY: Scar formation is a major medical problem that can have devastating consequences for patients. The adverse physiological and psychological effects of scars are broad, and there are currently no reliable treatments to prevent scarring. In contrast to adult wounds, early gestation fetal skin wounds repair rapidly and in the absence of scar formation. Despite extensive investigation, the exact mechanisms of scarless fetal wound healing remain largely unknown. For some time, it has been known that significant differences exist among the extracellular matrix, inflammatory response, cellular mediators, and gene expression profiles of fetal and postnatal wounds. These differences may have important implications in scarless wound repair.