Epidermal Potentiation of Dermal Fibrosis: Lessons from Occlusion and Mucosal Healing.

Fibrotic skin conditions, such as hypertrophic and keloid scars, frequently result from injury to the skin and as sequelae to surgical procedures. The development of skin fibrosis may lead to patient discomfort, limitation in range of motion, and cosmetic disfigurement. Despite the frequency of skin fibrosis, treatments that seek to address the root causes of fibrosis are lacking. Much research into fibrotic pathophysiology has focused on dermal pathology, but less research has been performed to understand aberrations in fibrotic epidermis, leading to an incomplete understanding of dermal fibrosis. Herein, literature on occlusion, a treatment modality known to reduce dermal fibrosis, in part through accelerating wound healing and regulating aberrant epidermal inflammation that otherwise drives fibrosis in the dermis, is reviewed. The review focuses on epidermal-dermal crosstalk, which contributes to the development and maintenance of dermal fibrosis, an underemphasized interplay that may yield novel strategies for treatment if understood in more detail.

Skin fibrosis is accompanied by increased expression of secreted frizzled-related protein-2.

Dermal fibrosis is a consequence of damage to skin and is accompanied by dysfunction and cosmetic disfigurement. Improved understanding of the pathological factors driving skin fibrosis is critical to development of therapeutic modalities. Here, we describe that the Wnt signalling antagonist SFRP2 is upregulated in organotypic keratinocyte cultures upon experimental reduced hydration, a model that simulates the aberrant epidermal barrier state characteristic of several skin pathologies, including those that manifest in development of fibrosis. Consistent with this, we find that SFRP2 is overexpressed in both the dermis and epidermis of human hypertrophic scar tissue and lesional tissue of a mouse scleroderma model. Knockdown of SFRP2 expression in human fibroblasts antagonises proliferation and myofibroblast differentiation, including deposition of type I collagen, suggesting that SFRP2 signalling in fibroblasts may contribute to propagation of fibrosis in hypertrophic scar, as well as in other clinical indications characterised by skin fibrosis.

Differential Anti-Fibrotic and Remodeling Responses of Human Dermal Fibroblasts to Artemisia sp., Artemisinin, and Its Derivatives.

Fibrosis is a ubiquitous pathology, and prior studies have indicated that various artemisinin (ART) derivatives (including artesunate (AS), artemether (AM), and dihydroartemisinin (DHA)) can reduce fibrosis in vitro and in vivo. The medicinal plant Artemisia annua L. is the natural source of ART and is widely used, especially in underdeveloped countries, to treat a variety of diseases including malaria. A. afra contains no ART but is also antimalarial. Using human dermal fibroblasts (CRL-2097), we compared the effects of A. annua and A. afra tea infusions, ART, AS, AM, DHA, and a liver metabolite of ART, deoxyART (dART), on fibroblast viability and expression of key fibrotic marker genes after 1 and 4 days of treatment. AS, DHA, and Artemisia teas reduced fibroblast viability 4 d post-treatment in up to 80% of their respective controls. After 4 d of treatment, AS DHA and Artemisia teas downregulated ACTA2 up to 10 fold while ART had no significant effect, and AM increased viability by 10%. MMP1 and MMP3 were upregulated by AS, 17.5 and 32.6 fold, respectively, and by DHA, 8 and 51.8 fold, respectively. ART had no effect, but A. annua and A. afra teas increased MMP3 5 and 16-fold, respectively. Although A. afra tea increased COL3A1 5 fold, MMP1 decreased >7 fold with no change in either transcript by A. annua tea. Although A. annua contains ART, it had a significantly greater anti-fibrotic effect than ART alone but was less effective than A. afra. Immunofluorescent staining for smooth-muscle α-actin (α-SMA) correlated well with the transcriptional responses of drug-treated fibroblasts. Together, proliferation, qPCR, and immunofluorescence results show that treatment with ART, AS, DHA, and the two Artemisia teas yield differing responses, including those related to fibrosis, in human dermal fibroblasts, with evidence also of remodeling of fibrotic ECM.

Amnion membranes support wound granulation in a delayed murine excisional wound model.

Chronic or delayed healing wounds constitute an ever-increasing burden on healthcare providers and patients alike. Thus, therapeutic modalities that are tailored to particular deficiencies in the delayed wound healing response are of critical importance to improve clinical outcomes. Human amnion-derived viable and devitalized allografts have demonstrated clinical efficacy in promoting the closure of delayed healing wounds, but the mechanisms responsible for this efficacy and the specific wound healing processes modulated by these tissues are not fully understood. Here, we utilized a diabetic murine excisional wound model in which healing is driven by granulation and re-epithelialization, and we applied viable (vHAMA) or devitalized (dHAMA) amnion-derived allografts to the wound bed in order to determine their effects on wound healing processes. Compared to control wounds that were allowed to heal in the absence of treatment, wounds to which vHAMA or dHAMA were applied demonstrated enhanced deposition of granulation tissue accompanied by increased cellular proliferation and increased de novo angiogenesis, while vHAMA-treated wounds also demonstrated accelerated re-epithelialization. Taken together, these data suggest that both vHAMA and dHAMA facilitate wound healing through promoting processes critical to granulation tissue formation. Further understanding of the cellular and tissue mechanisms underlying the effects of tissue-derived matrices on wound healing will enable tailored prescription of their use in order to maximize clinical benefit.

Comparative transcriptomic adaptations of Staphylococcus aureus to the wound environment in non-diabetic and diabetic mice.

Infection is a major source of complications in delayed diabetic wound healing. Increased understanding of differential bacterial responses to diabetic wounds will enable us to better understand chronic wound pathogenesis. Here we create delayed-healing wounds infected with Staphylococcus aureus in non-diabetic and diabetic mice and used RNA-seq to compare bacterial gene expression profiles 3 or 7 days after infection. Analysis at day 3 demonstrated substantial transcriptomic differences between bacteria colonising non-diabetic and diabetic wound beds. Most of these transcriptional differences resolved by day 7, suggesting normalisation of many bacterial phenotypes later in the diabetic wound healing process. Lingering differentially expressed genes at day 7 were enriched for genes related to carbohydrate metabolism, which includes genes of the lac operon, and capsular polysaccharide synthesis, which includes the cap8 locus. These data encourage further research into host-pathogen interactions in wound healing and how they influence differential outcomes in the diabetic wound environment.

A dehydrated, aseptically-processed human amnion/chorion allograft accelerates healing in a delayed murine excisional wound model.

Since chronic, non-healing wounds represent an increasing source of economic and temporal burden for patients who suffer from them and healthcare professionals that treat them, therapeutic modalities that promote closure of delayed and non-healing wounds are of utmost importance. Recent clinical results of allografts derived from amnion and chorion placental layers encourage further investigation of the mechanisms underlying clinical efficacy of these products for treatment of wounds. Here, we utilized a diabetic murine splinted excisional wound model to investigate the effects of a dehydrated human amnion/chorion-derived allograft (dHACA) on delayed wound healing, as well as the effects of dehydrated allograft derived solely from amnion tissue of the same donor. We examined wound healing by histological endpoint analysis, and we assessed other parameters relevant to functional wound healing in the wound bed including angiogenesis, macrophage phenotypes, proliferative activity, and gene expression. Herein we demonstrate that application of dHACA to a murine diabetic model of delayed wound progression results in better macroscale wound resolution outcomes, including rate of closure, compared to unaided wound progression, while dehydrated human amnion allograft (dHAA) fails to improve outcomes. Improved gross wound resolution observed with dHACA was accompanied by increased granulation tissue formation, proliferation and vascular ingrowth observed in the wound bed, early macrophage polarization towards anti-inflammatory phenotypes, and downregulation of pro-fibrotic gene expression. Overall, our data suggest that improvements in the rates of delayed wound closure observed from combined amnion/chorion allografts are associated with modulation of critical cellular and tissue processes commonly found to be dysregulated in delayed healing wounds, including proliferation, vascularization, inflammation, and re-epithelialization.

The Nax (SCN7A) channel: an atypical regulator of tissue homeostasis and disease.

Within an articulately characterized family of ion channels, the voltage-gated sodium channels, exists a black sheep, SCN7A (Nax). Nax, in contrast to members of its molecular family, has lost its voltage-gated character and instead rapidly evolved a new function as a concentration-dependent sensor of extracellular sodium ions and subsequent signal transducer. As it deviates fundamentally in function from the rest of its family, and since the bulk of the impressive body of literature elucidating the pathology and biochemistry of voltage-gated sodium channels has been performed in nervous tissue, reports of Nax expression and function have been sparse. Here, we investigate available reports surrounding expression and potential roles for Nax activity outside of nervous tissue. With these studies as justification, we propose that Nax likely acts as an early sensor that detects loss of tissue homeostasis through the pathological accumulation of extracellular sodium and/or through endothelin signaling. Sensation of homeostatic aberration via Nax then proceeds to induce pathological tissue phenotypes via promotion of pro-inflammatory and pro-fibrotic responses, induced through direct regulation of gene expression or through the generation of secondary signaling molecules, such as lactate, that can operate in an autocrine or paracrine fashion. We hope that our synthesis of much of the literature investigating this understudied protein will inspire more research into Nax not simply as a biochemical oddity, but also as a potential pathophysiological regulator and therapeutic target.

Application of decellularized human reticular allograft dermal matrix promotes rapid re-epithelialization in a diabetic murine excisional wound model.

BACKGROUND AIMS: The treatment and care of human wounds represent an enormous burden on the medical system and patients alike. Chronic or delayed healing wounds are characterized by the inability to form proper granulation tissue, followed by deficiencies in keratinocyte migration and wound re-epithelialization, leading to increased likelihood of infection and poor wound outcomes. Human reticular acellular dermal matrix (HR-ADM) is one type of tissue graft developed to enhance closure of delayed healing wounds that has demonstrated clinical utility through accelerating closure of lower extremity diabetic ulcers, but the mechanisms underlying this clinical success are not well understood. METHODS: The authors utilized a diabetic murine splinted excisional wound model to investigate the effects of HR-ADM application on wound closure. RESULTS: The authors demonstrate that application of HR-ADM served as a dermal scaffold and promoted rapid re-epithelialization and keratinocyte proliferation, resulting in accelerated wound closure while minimizing granulation tissue formation. HR-ADM-applied wounds also demonstrated evidence of cellular infiltration, neovascularization and collagen remodeling by the host organism. CONCLUSIONS: These data suggest that HR-ADM supports epidermal closure in delayed healing wounds and remodeling of the matrix into host tissue, lending further support to the clinical success of HR-ADM described in clinical reports.

Knockout of sodium channel Nax delays re-epithelializathion of splinted murine excisional wounds.

Mammalian wound healing is a carefully orchestrated process in which many cellular and molecular effectors respond in concert to perturbed tissue homeostasis in order to close the wound and re-establish the skin barrier. The roles of many of these molecular effectors, however, are not entirely understood. Our lab previously demonstrated that the atypical sodium channel Nax (encoded by Scn7a) responds to wound-induced epidermal dehydration, resulting in molecular cascades that drive pro-inflammatory signaling. Acute inhibition of Nax was sufficient to attenuate dermatopathological symptoms in models of hypertrophic scar and dermatitis. To date, however, the role of Nax in excisional wound healing has not been demonstrated. Here we report development of a knockout mouse that lacks expression of functional Nax , and we demonstrate that lack of functional Nax results in deficient wound healing in a murine splinted excisional wound healing model. This deficiency in wound healing was reflected in impaired re-epithelialization and decreased keratinocyte proliferation, a finding which was further supported by decreased proliferation upon Nax knockdown in HaCaT cells in vitro. Defective wound healing was observed alongside increased expression of inflammatory genes in the wound epidermis of Nax -/- mice, suggesting that mice lacking functional Nax retain the ability to undergo skin inflammation. Our observations here motivate further investigation into the roles of Nax in wound healing and other skin processes.

Liposome-encapsulated statins reduce hypertrophic scarring through topical application.

Hypertrophic scar is an important clinical problem with limited therapeutic options. Aside from their roles as 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, statins have also been demonstrated to decrease scarring by reducing connective tissue growth factor (CTGF) expression. However, poor penetrative ability limits their utility as topical treatments for hypertrophic scar. Here, we aim to develop novel statin formulations using liposomes to enhance dermal penetrative ability and to evaluate their efficacy against formation of hypertrophic scar utilizing our validated rabbit ear hypertrophic scar model. Liposomal simvastatin or pravastatin were compounded using a novel, flexible liposomal formulation and applied topically to rabbit ear hypertrophic scars daily from postoperation day (POD) 14 until POD 25. Scar color, including erythema and melanin, was measured using reflectance spectrophotometry on POD 28, and scar tissue was harvested for evaluation of scar elevation index as well as gene and protein expression. Human foreskin fibroblasts were also treated with statin formulations and CCN2 expression was determined by quantitative PCR. Both simvastatin and pravastatin were efficiently encapsulated in liposomes, forming nanometer-scale particles possessing highly negative charges. Topical treatment with liposomal simvastatin and pravastatin at 6.5% concentration significantly reduced scar elevation index and decreased type I/III collagen content and myofibroblast persistence in the wound. The erythema/vascularity of scars was reduced by liposomal statin treatment, with concomitant decrease of CD31 expression as measured histologically. Expression levels of transcripts encoding CTGF, collagen I, and collagen III collagen in scar tissue were also decreased by liposomal pravastatin treatment, as were myofibroblast persistence and the type I/III collagen ratio as assessed by immunofluorescence and picrosirus red staining, respectively. Treatment of human foreskin fibroblasts with simvastatin or with liposome-encapsulated pravastatin resulted in decreased expression of transcript encoding CTGF. Overall, our novel statin formulations encapsulated in liposomes were successfully delivered through topical application, significantly reducing hypertrophic scarring in a rabbit ear model.

Artesunate inhibits myofibroblast formation via induction of apoptosis and antagonism of pro-fibrotic gene expression in human dermal fibroblasts.

The anti-malaria drug artesunate and other chemical analogs of artemisinin have demonstrated cytostatic and cytotoxic effects in bacterial and cancer cells. Artemisinin-derived compounds have also been demonstrated to attenuate fibrosis in preclinical animal models, but the mechanisms by which this inhibition occurs are not well-understood. We investigated the effects of artesunate on the emergence of the myofibroblast, which is causally implicated in pro-fibrotic pathologies. CRL-2097 human dermal fibroblasts were analyzed for protein and transcript expression after treatment with artesunate to analyze fibroblast activation. Proliferation and apoptosis were also evaluated following treatment with artesunate in this cell line. Treatment of human dermal fibroblasts with artesunate antagonized fibroblast activation and pro-fibrotic extracellular matrix (ECM) deposition, both at basal culture conditions and when cultured in the presence of exogenous transforming growth factor-ß1 (TGF-ß1), a major pro-fibrotic cytokine. Artesunate-treated fibroblasts also demonstrated decreased proliferation and increased apoptosis. Transcript analysis by quantitative real-time polymerase chain reaction demonstrated that artesunate downregulated expression of pro-fibrotic genes including canonical myofibroblast markers, ECM genes, and several TGF-ß receptors and ligands, and upregulated expression of cell cycle inhibitors and matrix-metalloproteinases. Together, these data demonstrate that artesunate antagonizes fibroblast activation and decreases expression of pro-fibrotic genes, while also promoting myofibroblast apoptosis, suggesting that these mechanisms may be responsible in part for the anti-fibrotic effects of artesunate described previously.

Tryptophan metabolites kynurenine and serotonin regulate fibroblast activation and fibrosis.

Fibrosis is a pathological form of aberrant tissue repair, the complications of which account for nearly half of all deaths in the industrialized world. All tissues are susceptible to fibrosis under particular pathological sets of conditions. Though each type of fibrosis has characteristics and hallmarks specific to that particular condition, there appear to be common factors underlying fibrotic diseases. One of these ubiquitous factors is the paradigm of the activated myofibroblast in the promotion of fibrotic phenotypes. Recent research has implicated metabolic byproducts of the amino acid tryptophan, namely serotonin and kynurenines, in the pathology or potential pharmacologic therapy of fibrosis, in part through their effects on development of myofibroblast phenotypes. Here, we review literature underlying what is known mechanistically about the effects of these compounds and their respective pathways on fibrosis. Pharmacologic administration of kynurenine improves scarring outcomes in vivo likely not only through its well-characterized immunosuppressive properties but also via its demonstrated antagonism of fibroblast activation and of collagen deposition. In contrast, serotonin directly promotes activation of fibroblasts via activation of canonical TGF-ß signaling, and overstimulation with serotonin leads to fibrotic outcomes in vivo. Recently discovered feedback inhibition between serotonin and kynurenine pathways also reveals more information about the cellular physiology of tryptophan metabolism and may also underlie possible paradigms for anti-fibrotic therapy. Together, understanding of the effects of tryptophan metabolism on modulation of fibrosis may lead to the development of new therapeutic avenues for treatment through exploitation of these effects.

Cellular lifespan and senescence: a complex balance between multiple cellular pathways.

The study of cellular senescence and proliferative lifespan is becoming increasingly important because of the promises of autologous cell therapy, the need for model systems for tissue disease and the implication of senescent cell phenotypes in organismal disease states such as sarcopenia, diabetes and various cancers, among others. Here, we explain the concepts of proliferative cellular lifespan and cellular senescence, and we present factors that have been shown to mediate cellular lifespan positively or negatively. We review much recent literature and present potential molecular mechanisms by which lifespan mediation occurs, drawing from the fields of telomere biology, metabolism, NAD(+) and sirtuin biology, growth factor signaling and oxygen and antioxidants. We conclude that cellular lifespan and senescence are complex concepts that are governed by multiple independent and interdependent pathways, and that greater understanding of these pathways, their interactions and their convergence upon specific cellular phenotypes may lead to viable therapies for tissue regeneration and treatment of age-related pathologies, which are caused by or exacerbated by senescent cells in vivo.

Influence of Staphylococcus aureus Infection on Partially Ischemic Excisional Skin Wounds.

Background: Skin wounds, whether medically or incidentally induced, are always at a risk of becoming infected, but the infection risks are greater when the wounds are recovering under ischemic, poorly perfused conditions. Staphylococcus aureus, which frequently infects cutaneous and soft tissue, can infect to a greater extent when wounds are poorly perfused. Bad as this may be, both MSSA and MRSA strains of S. aureus can cause severe infections, with MRSA being considered more aggressive. Methods: In this study, we used a lagomorph ear excisional wound model to initially test the influence of partial ischemia on uninfected wound healing. We then subsequently test the same ischemic injury model under an active MSSA infection and compared these wounds against normally perfused MSSA-infected wounds. Lastly, we test whether differences in healing exist between MSSA-infected and MRSA-infected wounds, both under the same ischemic model. Results: The data suggest that partial ischemia considerably reduces healing of noninfected wounds (epithelial gap P=∗∗∗∗, granulation gap P=∗∗∗, and granulation area P=∗∗∗∗). Similarly, partial ischemic wounds coupled with MSSA infection display healing impairments against likewise-infected wounds healing under normal perfusion (epithelial gap P=∗, granulation gap P=∗, and granulation area P=∗∗). No significant differences were observed between MSSA-infected and MRSA-infected wounds healing under ischemia. Conclusion: The data produced quantitative differences in healing under various conditions consequent to ischemia and S. aureus infection. Although it is well recognized that ischemia and infection adversely influence healing, by testing these conditions, we determined the detrimental magnitude such circumstances inflict on skin healing, thereby providing a relative reference to compare and gauge when met with similar conditions clinically.

Cosmetic implant placement in the female breast yields an altered local and systemic immune response: evidence for breast cancer immunosurveillance.

BACKGROUND: Women with cosmetic implants have lower rates of future breast cancer than the general population. We hypothesized the implant foreign body response could induce a local protective anti-cancer immunosurveillance. We expanded on our previous finding which showed women with breast implants have elevated antibody responses to certain breast cancer proteins. METHODS: Blood samples and breast tissue were collected from women undergoing first time breast augmentation (implant-naive, IN) and revision breast augmentation (implant-exposed, IE). Sera were collected and antibody levels to common breast cancer proteins were quantified by enzyme-linked immunosorbent assay (ELISA). RT-PCR was performed on breast tissue samples to quantify immune-related gene expression levels between IN and IE. Bulk RNA sequencing was performed to identify differentially expressed genes and altered signaling pathways in the breasts of IN versus IE. RESULTS: In total, 188 patients were recruited (117 IN, 71 IE). Data demonstrated that IE patients had higher levels of antibodies to MUC-1, ER, and mammaglobin A compared to IN patients. MUC-1 expression was found to be higher in IE compared to IN breast tissue. RNA-seq analysis demonstrated upregulated pathways in IE breast tissue for B cell activation and development, Th2 related genes, T cell activation, chemotactic factors, and responses to estrogen. CONCLUSION: This is the first study to demonstrate that peri-implant inflammation extends beyond the implant capsule to breast parenchyma. Women with breast implants have more activated B cells in the breast parenchyma and elevated antibody responses to breast cancer antigen.

Comment on "Scar-Degrading Endothelial Cells as a Treatment for Advanced Liver Fibrosis".

Cellular therapies show promise for treatment of fibrosis. A recent article presents a strategy and proof-of-concept for delivering stimulated cells to degrade hepatic collagen in vivo. A discussion is presented surrounding the strengths of this approach and the potential to generalize this strategy of optimizing cell sources and activation stimuli to treat other types of fibrosis.

Prediction and Demonstration of Retinoic Acid Receptor Agonist Ch55 as an Antifibrotic Agent in the Dermis.

The prevalence of fibrotic diseases and the lack of pharmacologic modalities to effectively treat them impart particular importance to the discovery of novel antifibrotic therapies. The repurposing of drugs with existing mechanisms of action and/or clinical data is a promising approach for the treatment of fibrotic diseases. One paradigm that pervades all fibrotic diseases is the pathological myofibroblast, a collagen-secreting, contractile mesenchymal cell that is responsible for the deposition of fibrotic tissue. In this study, we use a gene expression paradigm characteristic of activated myofibroblasts in combination with the Connectivity Map to select compounds that are predicted to reverse the pathological gene expression signature associated with the myofibroblast and thus contain the potential for use as antifibrotic compounds. We tested a small list of these compounds in a first-pass screen, applying them to fibroblasts, and identified the retinoic acid receptor agonist Ch55 as a potential hit. Further investigation exhibited and elucidated the antifibrotic effects of Ch55 in vitro as well as showing antiscarring activity upon intradermal application in a preclinical rabbit ear hypertrophic scar model. We hope that similar predictions to uncover antiscarring compounds may yield further preclinical and ultimately clinical success.

Anti-fibrotic effects of statin drugs: A review of evidence and mechanisms.

Fibrosis is a pathological repair process common among organs, that responds to tissue damage by replacement with non-functional connective tissue. Despite the widespread prevalence of tissue fibrosis, manifesting in numerous disease states across myriad organs, therapeutic modalities to prevent or alleviate fibrosis are severely lacking in quantity and efficacy. Alongside development of new drugs, repurposing of existing drugs may be a complementary strategy to elect anti-fibrotic compounds for pharmacologic treatment of tissue fibrosis. Drug repurposing can provide key advantages to de novo drug discovery, harnessing the benefits of previously elucidated mechanisms of action and already existing pharmacokinetic profiles. One class of drugs with a wealth of clinical data and extensively studied safety profiles is the statins, a class of antilipidemic drugs widely prescribed for hypercholesterolemia. In addition to these widely utilized lipid-lowering effects, increasing data from cellular, pre-clinical mammalian, and clinical human studies have also demonstrated that statins are able to alleviate tissue fibrosis originating from a variety of pathological insults via lesser-studied, pleiotropic effects of these drugs. Here we review literature demonstrating evidence for direct effects of statins antagonistic to fibrosis, as well as much of the available mechanistic data underlying these effects. A more complete understanding of the anti-fibrotic effects of statins may paint a clearer picture of their anti-fibrotic potential for various clinical indications. Additionally, more lucid comprehension of the mechanisms by which statins exert anti-fibrotic effects may aid in development of novel therapeutic agents that target similar pathways but with greater specificity or efficacy.

Simvastatin cream alleviates dermal fibrosis in a rabbit ear hypertrophic scar model.

BACKGROUND: Hypertrophic scars (HTS) result from injury to the skin and represent a clinical burden with limited treatment options. Previously, we demonstrated that statin drugs could attenuate HTS formation, but convenient topical delivery and retention of these drugs at the wound site remains a challenge. AIMS: Here, we aimed to develop a topical cream formulation that can deliver statin drugs simply and conveniently to reduce scar hypertrophy. METHODS: We formulated creams containing 10% pravastatin, 2% simvastatin, and 10% simvastatin. We tested these creams for their ability to reduce scar hypertrophy and attenuate dermal fibrosis in a clinically relevant HTS wound model performed in rabbit ear skin. We also monitored trans-epidermal water loss (TEWL) over the course of wound healing in order to understand the effects of statin treatment on epidermal barrier recovery. RESULTS: Of the three creams formulated, only application of 10% simvastatin cream significantly attenuated hypertrophy of resultant scars compared with vehicle cream application. Application of 10% simvastatin cream resulted in a decrease in macrophage and myofibroblast density at post-operative day 28 (POD28) harvest. Application of 10% simvastatin cream resulted in visible symptoms of dryness and increased TEWL at POD28, but subsequent withdrawal of statin cream treatment resulted in rapid alleviation of dryness and decrease in TEWL back to normal levels. CONCLUSIONS: Our data demonstrate that topical administration of 10% simvastatin cream antagonizes dermal fibrosis and reduces hypertrophy in an HTS model, and withdrawal of the cream enables recovery of epidermal barrier and resolution of skin dryness.