So Let's Design a Peptide . . . A Physician's Approach.

This paper outlines a process undertaken by a physician to design a peptide aimed at impacting the extracellular matrix. From a position of very little expertise, a new peptide was designed with amino acid constituents based on the structural proteins collagen and elastin. Sequencing was also considered, given the periodic repetition observed in these proteins, and a peptide with reasonable molecular weight and physical characteristics was designed using available software. The sequence of events concerning intellectual property, functionality investigation, and eventual use of the peptide in new formulations is detailed. This may be of interest to physicians who consider this exercise out of the scope of the usual practice. J Drugs Dermatol. 2024;23(5):347-352.    doi:10.36849/JDD.7921.

Extension Phase of a Multi-Center, Randomized, Blinded Clinical Study Evaluating the Efficacy and Safety of a Novel Topical Product for Facial Dyschromia.

BACKGROUND: Dyschromia can be associated with increased production and/or reduced clearance of pigmentation in the skin. Multiple pathways are involved in causality. A novel topical product was recently developed, which contains actives that have been validated through in-vitro and clinical studies to counteract pigmentation related to photodamage, PIH, and melasma. This study further evaluates the safety and efficacy of this product for facial dyschromia during an additional 3-month extension period following the completion of the previous 12-week multi-center trial.  Study Design: Subjects from the previous multi-center trial with mild to severe facial dyschromia at baseline were eligible to participate in this 3-month extension study upon completion of that trial. This extension study evaluated the continued use of the novel topical product with PATH-3 Technology (Alastin Skincare, Carlsbad, CA) over a 3-month period. Subjects who were previously randomized to the novel topical product continued using it and for those previously randomized to hydroquinone 4% discontinued its use. Both cohorts continued daily sunscreen use. Blinded investigators assessed subjects at follow-up visits at 16, 20, and 24 weeks. RESULTS: Twenty-six (26) subjects completed the extension phase of the pivotal trial, with 13 subjects in each of the AL and HQ-BREAK cohorts. Significant improvements were seen within the AL cohort from weeks 12 to 24 for facial dyschromia (P=0.0158) and skin tone/clarity/evenness (P=0.0067), while there were no significant improvements seen in the HQ-BREAK cohort. The HQ-BREAK cohort had more subjects who worsened with facial dyschromia and skin tone/clarity/evenness. For the mMASI, the HQ-BREAK cohort demonstrated regression at week 24 compared to week 12, while the AL cohort instead experienced continued improvement. This difference was found to be significant (P=0.02). No study-related adverse events were reported for either cohort.  Conclusion: A novel topical product designed to counteract various steps in pigmentation pathways using PATH-3 Technology has been demonstrated to be safe and effective in treating facial dyschromia on a long-term basis. In contrast to the significant rebound experienced by subjects with HQ, the AL cohort continued to demonstrate ongoing improvement. J Drugs Dermatol. 2024;23(1):1266-1270.     doi:10.36849/JDD.7622.

Tissue Engineering Auricular Cartilage: A Review of Auricular Cartilage Characteristics and Current Techniques for Auricular Reconstruction.

Microtia and anotia are congenital auricular anomalies that negatively impact the psychosocial development of those affected. Because auricular cartilage is a type of elastic cartilage that lacks regenerative capacity, any notable defect in its structure requires a surgical approach to reconstructing the auricle. While there are several reconstructive options available between alloplastic and prosthetic implants, autologous rib cartilage grafts remain the most commonly used treatment modality. Still, this widely used technique is accompanied by significant patient discomfort in a young child and carries additional risks secondary to the traumatic process of rib cartilage extraction, such as pneumothorax and chest wall deformities, and the final esthetic results may not be ideal. To circumvent these limitations, tissue engineering approaches have been used to create a realistic-looking ear that mirrors the complex anatomy of the normal ear. This article reviews the biochemical and biomechanical properties of human auricular cartilage as they relate to design criteria. In addition, a variety of cell sources, biocompatible scaffolds, scaffold-free techniques, and mechanical and biological stimuli are discussed. This review aims to identify knowledge gaps in the literature related to auricular cartilage characteristics and make recommendations to drive the field of auricular tissue engineering.

WATCH VIDEO ABSTRACT: Dermatoporosis: Strategies for Rebuilding the Extracellular Matrix of the Skin.

Dermatoporosis as a disease entity is relatively newly described, the title conceived as recently as 2007. The background of chronic skin fragility, bruising, and atrophy appears to start in some patients as early as their mid-forties, but is full blown over the age of 65 years. The dehydration and fragility of the skin with recurrent bruising and breakdown were initially attributed to increased vessel fragility and permeability thought to be associated with inherent vascular tissue defects in a milieu of increased inflammation and extracellular matrix (ECM) degradation. It has subsequently been demonstrated that this ECM breakdown directly affects the structural support system of the superficial vessels, leading to stretch, increased permeability, and vulnerability to mechanical damage. Add to that the ECM atrophy and general accumulation of non-functional metabolic waste products in the form of fragmented collagen, elastin, and increased circulating glycation end products, and it becomes apparent that much of the problem resides in a structural defect, non-functioning, dehydrated, senescent cellular matrix and unsupported vascular system that presents as dermatoporotic characteristics. This paper describes a strategy of ECM replacement to counteract these foundational deficiencies. J Drugs Dermatol. 2023;22(9): doi:10.36849/JDD.7549.

Combining Allograft Adipose and Fascia Matrix as an Off-the-Shelf Scaffold for Adipose Tissue Engineering Stimulates Angiogenic Responses and Activates a Proregenerative Macrophage Profile in a Rodent Model.

OBJECTIVE: Bioscaffolds for treating soft tissue defects have limitations. As a bioscaffold, allograft adipose matrix (AAM) is a promising approach to treat soft tissue defects. Previously, we revealed that combining superficial adipose fascia matrix with AAM, components of the hypodermis layer of adipose tissue, improved volume retention, adipogenesis, and angiogenesis in rats 8 weeks after it was implanted compared with AAM alone. Here, we modified the fascia matrix and AAM preparation, examined the tissue over 18 weeks, and conducted a deeper molecular investigation. We hypothesized that the combined matrices created a better scaffold by triggering angiogenesis and proregenerative signals. METHODS: Human AAM and fascia matrix were implanted (4 [1 mL] implants/animal) into the dorsum of male Fischer rats (6-8 weeks old; ~140 g) randomly as follows: AAM, fascia, 75/25 (AAM/fascia), 50/50, and 50/50 + hyaluronic acid (HA; to improve extrudability) (n = 4/group/time point). After 72 hours, as well as 1, 3, 6, 9, 12, and 18 weeks, graft retention was assessed by a gas pycnometer. Adipogenesis (HE), angiogenesis (CD31), and macrophage infiltration (CD80 and CD163) were evaluated histologically at all time points. The adipose area and M1/M2 macrophage ratio were determined using ImageJ. RNA sequencing (RNA-seq) and bioinformatics were conducted to evaluate pathway enrichments. RESULTS: By 18 weeks, the adipose area was 2365% greater for 50/50 HA (281.6 ± 21.6) than AAM (11.4 ± 0.9) (P < 0.001). The M1/M2 macrophage ratio was significantly lower for 50/50 HA (0.8 ± 0.1) than AAM (0.9 ± 0.1) at 6 weeks (16%; P < 0.05). This inversely correlated with adipose area (r = -0.6; P > 0.05). The RNA-seq data revealed that upregulated adipogenesis, angiogenesis, and macrophage-induced tissue regeneration genes were temporally different between the groups. CONCLUSIONS: Combining the fascia matrix with AAM creates a bioscaffold with an improved retention volume that supports M2 macrophage-mediated angiogenesis and adipogenesis. This bioscaffold is worthy of further investigation.

Targeting Myofibroblasts as a Treatment Modality for Dupuytren Disease.

PURPOSE: Currently, no treatment corrects the contractile nature of Dupuytren myofibroblasts (DMFs) or prevents recurrence following surgery. Antifibrotic and proadipogenic growth factors are released when adipose-derived stem cells (ASCs) are cultured with platelet-rich plasma (PRP), a platelet concentration from whole blood. Reprograming myofibroblasts into adipocytes via growth factors is proposed as a powerful potential tool to target fibrosis. We aimed to assess whether the combination of ASCs and PRP reprograms DMFs into adipocytes in vitro and alters their contractile nature in vivo. METHODS: Normal human dermal fibroblasts (NHDFs) and DMFs from Dupuytren patients were isolated and cocultured with ASCs and PRP either alone or together. Adipocytes were detected by Oil Red O and perilipin staining. DMFs and NHDFs were transplanted into the forepaws of rats (Rowett Nude [rnu/rnu]) and treated with saline, PRP+ASCs, or collagenase Clostridium histolyticum (clinical comparison) 2 months later. After 2 weeks, the tissue was harvested and subjected to Masson trichrome staining, and collagen I and III and alpha-smooth muscle actin detection by immunohistochemistry. RESULTS: Myofibroblasts transform into adipocytes upon coculture with PRP+ASCs. DMFs show increased alpha-smooth muscle actin expression in vivo compared with NHDFs, which is significantly decreased after PRP+ASCs and collagenase Clostridium histolyticum treatments. DMFs induce collagen I and III expressions in rat paws compared with NHDFs, with a type III to I ratio increase. Treatment with PRP+ASC reduced the ratio, but collagenase Clostridium histolyticum did not. CONCLUSIONS: Treating DMFs with PRP+ASCs provides factors that induce myofibroblast to adipocyte transformation. This treatment reduces the contractile phenotype and fibrosis markers in vivo. Future studies should detail the mechanism of this conversion. CLINICAL RELEVANCE: The combination of PRP and ASCs to induce the differentiation of DMFs into adipocytes may serve to limit surgery to a percutaneous contracture release and biological injection, rather than a moderate or radical fasciectomy, and reduce the recurrence of Dupuytren contracture.

Hyperbaric and topical oxygen therapies in thermal burn wound healing: a review

OBJECTIVE: This review aims to evaluate the effectiveness of the two most commonly used oxygen delivery methods for the treatment of thermal burn wound healing: hyperbaric oxygen therapy (HBOT) and topical oxygen therapy (TOT). METHOD: The PubMed database was searched for articles discussing the use of HBOT or TOT in the treatment of thermal burns. RESULTS: The search yielded 43,406 articles, of which 28 (23 HBOT, 5 TOT) met the inclusion criteria. Both experimental and clinical studies have demonstrated conflicting results after treating thermal burns with HBOT or TOT. Overall, 14/23 studies demonstrated positive results for HBOT on the healing of burn wounds and associated complications, such as oedema and pain. Findings from these studies showed it can reduce morbidity and mortality in certain high-risk groups such as those with diabetes or extensive burns. Although the five studies (one human and four animal trials) reviewing TOT showed promising outcomes, this therapeutic modality has not been well investigated. CONCLUSION: Therapeutic use of HBOT in thermal burns has been popular in the past but its use remains controversial due to inconsistent results, serious side-effects, lack of convenience and high costs. The use of TOT in the management of burns needs further exploration by scientists and clinicians alike, in addition to the implementation of a standardised treatment protocol.

A Quantitative Assessment of Wound Healing With Oxygenated Micro/Nanobubbles in a Preclinical Burn Model.

BACKGROUND: Burns are devastating injuries, carry significant morbidity, and require long-term treatment or multiple reconstructive procedures. Wound healing and secondary insults caused by burn wound conversion are amendable to therapeutic intervention, where ischemia has been cited as one of the major factors (Dermatol Surg. 2008;34:1159-1169). Halting injury progression in the zone of stasis is crucial as conversion creates increased burn surface area and depth, leading to local and systemic consequences (J Burns Wounds. 2006;5:e2). Oxygen-carrying micro/nanobubbles, MNB(O2), offer a novel technology that can be used to effectively deliver oxygen to burn wounds and potentially counteract burn wound ischemia. METHODS: Topical irrigation with MNB(O2) of full-thickness burn wounds on a rodent model (n = 3) was compared against saline-treated controls (n = 3). Tissue structure (reduced scattering coefficient, µs'), oxyhemoglobin concentration (cHbO2), and tissue perfusion were quantified over the course of 28 days through spatial frequency domain imaging and laser speckle imaging. Histological samples taken at the end of the experiment were examined for evidence of wound healing. RESULTS: Findings in this preliminary study showed hastened healing with significant differences in spatial frequency domain imaging-measured µs' during wound healing (days 11-28) in MNB(O2) group. The healing "tipping point" seemed to occur at days 9 to 11 with increased collagen organization and increased cHbO2 occurring around that period confirming the gross healing improvements observed. In addition, histological evidence indicated that only the MNB(O2) burns had reached the remodeling phase by the end of 28-day study period. CONCLUSIONS: These preliminary findings propose the potential of MNB(O2) as a topical method for improving burn wound healing.

Developing a Topical Adjunct to Injectable Procedures.

Injectable procedures have come to play an enormous part in everyday aesthetic medical practice. Whether its use is directed at volumizing with fillers, decreasing volume using enzymes, skin-tightening using multi-needle approaches, or neuromuscular blockade, the injectable route is the means of delivery in all these cases, making injectable procedures the most common aesthetic procedure performed. As with all procedures, expected and unexpected consequences may follow including bruising, swelling, discomfort, and the possibility of infection. This paper outlines the scientific process and validation of a product designed as an adjunct to injection therapy and the scientific deep dive needed to encompass both symptomatic and adjunctive purposes. On the symptomatic side, bruising, swelling, and pain were considered, while volumetric enhancement, regeneration, and anti-microbial/biofilm effects were desired outcomes from the adjunctive perspective. Utilizing peptides and active agents aimed at reducing excess residual iron and stimulating macrophage absorption of red blood cells, we were able to achieve efficient resolution of bruising. In addition, peptides were included to stimulate collagen, elastin, and hyaluronic acid in synergy with the injectable. Anti-inflammatory, antimicrobial, and antibiofilm agents were added to aid in the safety profile of the injectable. In vivo testing of bruising resolution demonstrated that at day 2/3, participants using the study product (INhance Post-Injection Serum with TriHex Technology®, Alastin Skincare, Inc. Carlsbad, CA) had 73% less bruise color intensity and statistically significant improvement over the bland moisturizer. Overall, 81% of subjects applying the study topical product had less bruising at day 2/3 compared to the bland moisturizer. J Drugs Dermatol. 2020;19(4):398-404. doi:10.36849/JDD.2020.5016.

Mesenchymal stem cell dysfunction in diabetes.

Diabetes mellitus (DM) is a chronic disease that results in a variety of systemic complications. Recently, stem cell-based therapies have been proposed as potential modalities to manage DM related complications. Mesenchymal stem cell (MSC) based therapies are often considered as an ideal stem cell-based treatment for DM management due to their immunosuppressive characteristics, anti-inflammatory properties and differentiation potential. While MSCs show tremendous promise, the underlying functional deficits of MSCs in DM patients is not well understood. Using the MEDLINE database to define these functional deficits, our search yielded 1826 articles of which 33 met our inclusion criteria. This allowed us to review the topic and illuminate four major molecular categories by which MSCs are compromised in both Type 1 DM and Type II DM models which include: (1) changes in angiogenesis/vasculogenesis, (2) altered pro-inflammatory cytokine secretion, (3) increased oxidative stress markers and (4) impaired cellular differentiation and decreased proliferation. Knowledge of the deficits in MSC function will allow us to more clearly assess the efficacy of potential biologic therapies for reversing these dysfunctions when treating the complications of diabetic disease.

Gene Expression Studies Pertaining to Extracellular Matrix Integrity and Remodeling: Nuances and Pitfalls of In Vitro Investigations

Anti-aging strategies using topicals with active agents demand validation and proof of efficacy. One investigation in this realm involves gene expression testing. This study undertakes gene expression analysis of Alastin Skincare Regenerating Skin Nectar (RSN) using an in vitro human skin model. The current study is similar to other published human skin model studies, but with additional time periods beyond 24-hours (which are more appropriate for testing peptides) and a suitable control for the Alastin non-aqueous product. Results show the Alastin product upregulates a large array of genes within areas of skin renewal, extracellular matrix remodeling, barrier function, and inflammation after 72 hours. The study provides gene expression data that support the clinical success of the product. It also demonstrates the difficulty and vulnerabilities in assessing efficacies of products with certain in vitro investigations when the nuances of that product are not considered. J Drugs Dermatol. 2019;18(12):1255-1259.

A Double-Blind Randomized Controlled Trial Evaluating the Efficacy and Tolerability of a Topical Body Treatment in Combination With Cryolipolysis Procedures

Background: Non-surgical fat reduction through cold application, cryolipolysis, is an extremely popular procedure. Apoptosis of the fat cell content may take around 3 months to resolve. Objective: A topical test product was compared to a bland emollient as an adjunct to the cryolipolysis procedure of the upper arms to determine if the product could hasten outcomes in these patients. The product includes a peptide combination thought to stimulate autophagic breakdown of lipid droplets, thus speeding up the apoptotic process seen after cryolipolysis. Methods: A randomized, double-blind, comparator-controlled study in 11 patients compared the test product to a bland emollient on the upper arms of patients following cryolipolysis. Subjects were followed at 1, 4, 8, 12, and some at 24-weeks post treatment. Assessments were made through subjective and objective photographic analysis of the treated areas comparing changes in both arms. Results: The test product appeared to speed up the process of contour improvement with results at 8 weeks matching those attained at 12 weeks by the comparator and long-term results at 24 weeks appearing to maintain this advantage. When measured objectively using pixel analysis, 8 and 24-week contour improvement was statistically better than the comparator. Skin laxity was also improved. In additional assessments using 3D volume analysis, cases showed improved reduction of fat tissue on the treated sides. Conclusion: This pilot study introduces a potential advance in adjuvant topical therapy aiding the outcome of non-invasive fat reduction procedures. J Drugs Dermatol. 2019;18(4):342-348.

Non-Surgical Fat Reduction and Topical Modulation of Adipose Tissue Physiology

Non-surgical fat reduction procedures have gained in popularity over the past few years and remain in great demand. The process results in accumulation of breakdown products, lipid droplets, that are slowly absorbed over a period of months. This paper outlines the physiological process whereby lipid droplets are absorbed through a process of autophagy (lipophagy) involving a repackaging of these droplets to smaller sizes so that macrophages can then cope with digestion of these very large particles. Furthermore, a fat compartment is described within the dermis surrounding the tail of the hair follicle, which is attracting much attention due to its unique phenotype, function, and connection to the deeper subcutaneous fat compartment. This provides an entry route for direct signaling to the subcutaneous fat. Related to these novel concepts, peptides can be designed in liposomal delivery systems to target lipid droplet breakdown via the hair follicle entry route. This concept is elucidated in this paper. J Drugs Dermatol. 2019;18(4):375-380.

The Molecular Pathogenesis of Dupuytren Disease: Review of the Literature and Suggested New Approaches to Treatment.

BACKGROUND: Ever since the classification of Dupuytren disease into the proliferative, involutional, and residual stages, extensive research has been performed to uncover the molecular underpinnings of the disease and develop better treatment modalities for patients. The aim of this article is to systematically review the basic science literature pertaining to Dupuytren disease and suggest a new approach to treatment. METHODS: Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, a systematic review was conducted using the MEDLINE database to identify basic science literature on Dupuytren pathophysiology falling under 1 or more of the following categories: (1) Molecular alterations, (2) Structural alterations, and (3) Genetic predisposition. RESULTS: A total of 177 articles were reviewed of which 77 studies met inclusion criteria. Articles were categorized into respective sections outlined in the study methods. CONCLUSION: The pathophysiological changes involved in Dupuytren's disease can be divided into a number of molecular and structural alterations with genetic predisposition playing a contributory role. Understanding these changes can allow for the development of biologics which may disrupt and halt the disease process.

Micro/nanobubbles: Improving Pancreatic Islet Cell Survival for Transplantation.

PURPOSE: The preservation of transplantable tissue is directly tied to and limited by the ischemia time. Micro/nanobubbles (MNBs) are miniature gaseous voids that allow for the oxygenation of tissue given their high oxygen-carrying capacity. One of the current limitations of islet cell transplantation for type 1 diabetes is poor islet survival, caused by hypoxia, after harvesting the cells from pancreata. As such, the purpose of this study was to elucidate whether MNBs, when added to standard culture medium, improve islet cell survival postharvest. MATERIALS AND METHODS: Islet cells were harvested from Sprague-Dawley rat pancreas tissue via a standard collagenase digestion and gradient purification. To create the MNB solution, a shear-based generation system was used to produce both air- and oxygen-filled MNBs in standard Connaught Medical Research Laboratories (CMRL) medium. Four groups, consisting of 500 islet equivalents, were cultured with either the standard CMRL medium, macrobubble-CMRL, MNB (air)-CMRL, or MNB (O2)-CMRL, and they were incubated at 37°C. Each treatment solution was replenished 24 hours postincubation, and after 48 hours of culture, dithizone staining was used to determine the islet cell counts, and the viability was assessed using Calcein AM/propidium iodide staining. RESULTS: Islet cells that were preserved in macrobubble-CMRL, MNB (air)-CMRL, and MNB (O2)-CMRL conditions showed an increased survival compared with those cultured with standard CMRL. The islet cells cultured in the MNB (air)-CMRL condition demonstrated the greatest cell survival compared with all other groups, including the pure oxygen-carrying MNBs. None of the MNB treatments significantly altered the viability of the islet cells compared to the control condition. CONCLUSIONS: The addition of MNBs to culture medium offers an innovative approach for the oxygenation of transplantable tissue, such as islet cells. This study demonstrated that MNBs filled with air provided the most optimal addition to the islet cell culture medium for improving islet cell survival amongst the treatment groups we tested. Given these findings, we hypothesize that MNBs may also improve the oxygenation and survival of a variety of other tissues, including fat grafts from lipoaspirate, chronic wounds, and solid organs.

Preoperative Skin Conditioning: Extracellular Matrix Clearance and Skin Bed Preparation, A New Paradigm.

This paper introduces the concept of "skin bed preparation" prior to surgical procedures. Following the theory of chronic wound bed preparation and adapting the skin model to one of chronic wound changes related to extrinsic and intrinsic factors, a topical formulation aimed at recycling the extracellular matrix (ECM) from accumulated waste products is evaluated and discussed. The clearance of these products and stimulation of new replacements has the potential to change the regenerative milieu of the skin so that when procedures are carried out, cellular signaling and cross-talk at the dermal level are improved and healing is optimized. By introducing a combination of peptides and other synergistic active agents, a sequence of clearance, regeneration, and remodeling is initiated. This is confirmed and validated by a series of biopsies and clinical studies that demonstrate changes in the ECM as early as 2 to 3 weeks after application. Clinical studies related to resurfacing procedures show accelerated healing and improved symptomatic relief compared with standard of care by preconditioning the skin 2 weeks prior to the procedure. A similar approach is suggested as a potential advantage for invasive surgical procedures based on similar scientific principles elucidated on in the text.

The New Frontier: A Review of Augmented Reality and Virtual Reality in Plastic Surgery.

Mixed reality, a blending of the physical and digital worlds, can enhance the surgical experience, leading to greater precision, efficiency, and improved outcomes. Various studies across different disciplines have reported encouraging results using mixed reality technologies, such as augmented and virtual reality. To provide a better understanding of the applications and limitations of this technology in plastic surgery, we performed a systematic review of the literature in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The initial query of the National Center for Biotechnology Information database yielded 2544 results, and only 46 articles met our inclusion criteria. The majority of studies were in the field of craniofacial surgery, and uses of mixed reality included preoperative planning, intraoperative guides, and education of surgical trainees. A deeper understanding of mixed reality technologies may promote its integration and also help inspire new and creative applications in healthcare.

Platelet-Rich Plasma, Adipose Tissue, and Scar Modulation.

Level of Evidence: 4.

Topical oxygen therapy & micro/nanobubbles: a new modality for tissue oxygen delivery.

Up to 15 billion dollars of US health care expenditure each year is consumed by treatment of poorly healing wounds whose etiologies are often associated with aberrancies in tissue oxygenation. To address this issue, several modes of tissue oxygen delivery systems exist, including Hyperbaric Oxygen Therapy (HBOT) and Topical Oxygen Therapy (TOT), but their efficacies have yet to be fully substantiated. Micro/nanobubbles (MNBs), which range anywhere from 100 µm to <1 µm in diameter and are relatively stable for hours, offer a new mode of oxygen delivery to wounds. The aim of this article is to systematically review literature examining the use of TOT for wound healing and use of MNBs for tissue oxygenation using the MEDLINE database. The search yielded 87 articles (12 MNB articles and 75 TOT articles), of which 52 met the inclusion criteria for this literature review (12 MNB articles and 40 TOT articles). Additionally, we present an analysis on the efficacy of our MNB generating technology and propose its use as a wound healing agent.

Deconstructing negative pressure wound therapy.

Since its introduction 20 years ago for the treatment of chronic wounds, negative pressure wound therapy use has expanded to a variety of other wound types. Various mechanisms of action for its efficacy in wound healing have been postulated, but no unifying theory exists. Proposed mechanisms include induction of perfusion changes, microdeformation, macrodeformation, exudate control and decreasing the bacterial load in the wound. We surmise that these different mechanisms have varying levels of dominance in each wound type. Specifically, negative pressure wound therapy is beneficial to acute open wounds because it induces perfusion changes and formation of granulation tissue. Post-surgical incisional wounds are positively affected by perfusion changes and exudate control. In the context of chronic wounds, negative pressure wound therapy removes harmful and corrosive substances within the wounds to affect healing. When skin grafts and dermal substitutes are used to close a wound, negative pressure wound therapy is effective in promoting granulation tissue formation, controlling exudate and decreasing the bacterial load in the wound. In this review, we elucidate some of the mechanisms behind the positive wound healing effects of negative pressure wound therapy, providing possible explanations for these effects in different wound types.