Interleukin-10 Producing T Lymphocytes Attenuate Dermal Scarring.

OBJECTIVE: Demonstrate the impact of IL-10 producing T lymphocytes on mediating dermal scarring. SUMMARY BACKGROUND DATA: We demonstrated that CD4+ cells are essential to improving postinjury wound healing and preventing fibrosis. CD4+ subsets secrete differential cytokine and growth factor profiles, though their role in fibrosis is not known. IL-10, a key anti-inflammatory cytokine shown to promote regenerative wound healing, is secreted by some CD4+ subsets. We, therefore, hypothesize that IL-10 producing CD4+ T lymphocyte subsets selectively attenuate dermal wound fibrosis. METHODS: IL-10-/- and wild-type murine splenocytes were enriched for CD4+ lymphocytes and adoptively transferred into severe combined immunodeficient (SCID) mice that received full-thickness wounds which were analyzed at days 7 and 28 for inflammation and collagen content. We then sorted CD4+CD44int/lowFoxP3-CD62L+ T cells (Tnaive) or CD4+CD44HiFoxP3- type 1 regulatory (Tr1) T cell subsets from 10BiT murine splenocytes, activated them, and transferred them into wounds. In vitro, dermal fibroblasts were cocultured with Tnaive or Tr1 and the effect on extracellular matrix (ECM) regulation was analyzed. RESULTS: The anti-inflammatory and antifibrotic effects of CD4+ cells on SCID wounds were lost with cells from IL-10-/- mice. Adoptive transfer of Tr1 into SCID mice resulted in accelerated wound closure at d7 with reduced fibrosis at d28, with Tr1 favoring hyaluronan production by fibroblasts, an ECM molecule implicated in IL-10-induced regenerative healing. CONCLUSIONS: IL-10 producing T-lymphocytes, specifically Tr1, regulate inflammatory cell cytokine expression to promote HA-rich ECM deposition and attenuate fibrosis. Promoting IL-10 producing lymphocytes in wounds may be a therapeutic target to promote regenerative wound healing.

Protective effects of dissolved molecular hydrogen against hydrogen peroxide-, hydroperoxide-, and glyoxal-induced injuries to human skin keratinocytes.

Molecular hydrogen (H2) is recognized as a gaseous antioxidant, and it is expected to ameliorate various disorders related to oxidative stress and inflammation. However, there are still many unclear points regarding its effectiveness in the skin. Therefore, the purpose of this study was to examine the protective effect of H2 against ultraviolet (UV) irradiation-related stress injury in human epidermal HaCaT cells. We investigated the effects of H2 against three types of UV-derived oxidative stress using human skin keratinocytes: hydrogen peroxide (H2O2)-induced oxidative stress, tert-butyl hydroperoxide (t-BuOOH)-induced lipid peroxidation stress, and glyoxal-induced carbonyl stress. Our results showed that H2 exerted cytoprotective effects against stress induced by H2O2, t-BuOOH, and glyoxal. Furthermore, our results also revealed that H2 suppressed H2O2-induced increases in intracellular peroxide and H2O2 levels, and suppressed the progression of lipid peroxidation. Taken together, our results demonstrate that H2 can exert protective effects against oxidative stress-, lipid peroxidation-, and carbonyl stress-induced cellular injuries in human keratinocytes, partly mediated via suppression of intracellular oxidative stress and peroxide generation. Therefore, H2 is expected to be utilized as an effective and attractive component in cosmetic formulations in the future.

Dermal Drivers of Injury-Induced Inflammation: Contribution of Adipocytes and Fibroblasts.

Irregular inflammatory responses are a major contributor to tissue dysfunction and inefficient repair. Skin has proven to be a powerful model to study mechanisms that regulate inflammation. In particular, skin wound healing is dependent on a rapid, robust immune response and subsequent dampening of inflammatory signaling. While injury-induced inflammation has historically been attributed to keratinocytes and immune cells, a vast body of evidence supports the ability of non-immune cells to coordinate inflammation in numerous tissues and diseases. In this review, we concentrate on the active participation of tissue-resident adipocytes and fibroblasts in pro-inflammatory signaling after injury, and how altered cellular communication from these cells can contribute to irregular inflammation associated with aberrant wound healing. Furthering our understanding of how tissue-resident mesenchymal cells contribute to inflammation will likely reveal new targets that can be manipulated to regulate inflammation and repair.

Effects of Pulsed 810 nm Al-Ga-As Diode Laser on Wound Healing Under Immunosuppression: A Molecular Insight.

BACKGROUND AND OBJECTIVES: Dysregulated inflammation is one of the major contributing factors for the prevalence of non-healing chronic wound in immunosuppressed subjects. Photobiomodulation (PBM) has emerged as a potential non-thermal, light-based therapeutic healing intervention for the treatment of impaired wounds. STUDY DESIGN/MATERIALS AND METHODS: The present study delineates the underlying molecular mechanisms of PBM 810 nm laser-induced full-thickness cutaneous wound repair in immunosuppressed rats at continuous and pulsed wave-mode with power-density of 40 mW/cm 2 , fluence 22.6 J/cm 2 for 10 minutes daily for 7 post-wounding days. Molecular markers were assessed using biochemical, enzyme-linked immunosorbent assay quantification, enzyme kinetics and immunoblots analyses pertaining to inflammation, oxidative stress, cell survival, calcium signaling, and proliferation cascades. RESULTS: Results distinctly revealed that pulsed 810 nm (10 Hz) PBM potentially influenced the cell survival and proliferation signaling pathway by significantly upregulated phospho-protein kinase B(phospho-Akt), phospho-extracellular-signal-regulated kinase 1 (ERK1), transient receptor potential vanilloid-3 (TRPV3), Ca2+ , calmodulin, transforming growth factor-ß1 (TGF-ß1), TGF-ßR3, and Na + /K + -ATPase pump levels. PBM treatment resulted in reduction of exaggerated inflammatory responses evident by significantly repressed levels of interleukin-1ß (IL-1ß), IL-6, cyclooxygenase 2 (COX-2), and substance-P receptor (SPR), as well as inhibited apoptotic cell death by decreasing p53, cytochrome C, and caspase 3 levels (P < 0.05), which, in turn, effectively augment the wound repair in immunosuppressed rats. PBM treatment also lowered 4-hydroxynoneal (HNE) adduct level and NADP/NADPH ratio and upregulated the GRP78 expression, which might culminate into reduced oxidative stress and maintained the redox homeostasis. CONCLUSIONS: Taken together, these findings would be helpful in better understanding of the molecular aspects involved in pulsed 810 nm laser-mediated dermal wound healing in immunosuppressed rats through regulation of cell survival and proliferation via Ca2+ -calmodulin, Akt, ERK, and redox signaling. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Modelling optimal delivery of bFGF to chronic wounds using ODEs.

In this paper, we present an ordinary differential equation model depicting the interactions of basic fibroblast growth factor (bFGF) and its binding agents in a chronic wound. The delivery of bFGF was treated as a control variable and is coupled to an objective functional. By optimising the objective functional with respect to the control, predictions for optimal delivery rates of bFGF are proposed. The optimal control is then validated by comparing the cost of the objective functional for the optimal delivery rate and several alternative delivery rates. This paper addresses two objectives of effective drug delivery to chronic wounds. The first is to provide insight for the priority of delivering bFGF: to minimise the quantity of bFGF, or to optimise the distribution of bound bFGF. For effective concentrations of bound bFGF, the optimisation of bound bFGF must be prioritised over the minimisation of bFGF delivered. The second objective is to comment on the effect of the proteolytic environment within the wound, with the concentration of bound bFGF starting to decrease late in the treatment period for highly proteolytic environments. This will lead to long term complications with wound closure after the treatment has been completed. Also, it was found that for highly proteolytic environments, the cost of delivering bFGF increased. The need for optimal drug delivery is made apparent by the burden of chronic wounds on the medical industry across the developed world.

Interactive thermal tissue reactions of 7-MHz intense focused ultrasound and 1-MHz and 6-MHz radiofrequency on cadaveric skin.

BACKGROUND: Intense focused ultrasound (IFU) and radiofrequency (RF) systems generate thermal tissue reactions in multiple zones in the skin, with the microscopic features thereof varying according to energy sources and treatment parameters. OBJECTIVE: To evaluate interactive thermal tissue reactions of IFU and RF in cadaveric skin. METHODS: Thermal reaction patterns generated by IFU, invasive bipolar RF, and non-invasive monopolar RF treatments were analyzed in cadaveric skin of the inner thigh. Additionally, combination treatment, including IFU and invasive bipolar RF, IFU and non-invasive monopolar RF, invasive bipolar RF and IFU, and non-invasive monopolar RF and IFU, was delivered to cadaveric skin and microscopically evaluated. RESULTS: Combination treatment with 1.5-mm IFU followed by 1.5-mm invasive RF elicited multiple thermal injury zones of coagulation and ablation in the mid to lower dermis. Therein, IFU-induced thermal reactions were indistinguishable from RF-induced thermal reactions. Non-invasive RF treatment on IFU-pretreated cadaveric tissue specimens exhibited greater degrees of thermal injury, with wider and deeper penetration, compared to non-invasive RF treatment alone. Furthermore, RF-pretreated tissues showed marked differences in the patterns of IFU-induced thermal tissue reactions. CONCLUSION: Our data suggest that combination treatments with IFU and RF elicit various patterns of interactive thermal tissue reactions.

High-frequency (20-MHz) high-intensity focused ultrasound (HIFU) system for dermal intervention: Preclinical evaluation in skin equivalents.

BACKGROUND: High-intensity focused ultrasound (HIFU) for non-invasive treatment of a range of internal pathologies including cancers of major organs and cerebral pathologies is in exponential growth. Systems, however, operate at relatively low frequencies, in the range of 200-2000 kHz as required for deep axial penetration of the body. HIFU utilizing frequencies in excess of 15 MHz has so far not been explored, but presents an opportunity to extend the HIFU modality to target specific dermal lesions and small animal research. MATERIALS AND METHODS: A new 20-MHz HIFU system (TOOsonix ONE-R) with narrow focus corresponding to the dermis was studied in acoustic skin equivalents, for example, in a tissue-mimicking gel and in bovine liver. HIFU lesion geometry, depth, and diameter were determined. The temperature increase in the focal point was measured as a function of acoustic power and the duration of HIFU exposure. RESULTS: The system produces highly reproducible ultrasound lesions with predictable and configurable depths of 1-2 mm, thus corresponding to the depth of the human dermis. The lesion geometry was elongated triangular and sized 0.1-0.5 mm, convergent to a focal point skin deep. Focal point temperature ranged between 40 and 90°C depending on the chosen setting. Observations were confirmed ex vivo in bovine liver and porcine muscle. Variation of acoustic power and duration of exposure produced linear effects in the range of the settings studied. Thus, effects could be adjusted within the temperature interval and spatial field relevant for clinical therapy and experimental intervention targeting the dermal layer of human skin. CONCLUSION: The tested 20-MHz HIFU system for dermal applications fulfilled key prerequisite of narrow-field HIFU dedicated to cutaneous applications regarding reproducibility, geometry, and small size of the applied ultrasound lesions. Controlled adjustment of acoustic lesions within the temperature range 40-90°C qualifies the system for a range of non-ablative and ablative applications in dermatological therapy.

Skin regeneration of amphibians: A novel model for skin regeneration as adults.

Adult mammals do not regenerate the dermis of the skin but form a scar after a deep skin injury. Since a scar causes serious medical problems, skin regeneration, instead of formation of a scar, has been strongly desired from a clinical point of view. Recent studies have suggested multiple origins of myofibroblasts, which are scar-forming cells in skin wound healing of mammals. While amphibians have skin structures that are basically common to mammals as tetrapods, both urodele and anuran amphibians regenerate almost complete skin structures including the dermis and secretion glands without forming a remarkable scar after a deep skin injury. In skin regeneration of a metamorphosed Xenopus laevis, an amphibian, cells that resemble limb blastema cells accumulate under the epidermis after injury and cells from subcutaneous tissues (tissues underlying the skin) contribute to skin regeneration. The skin of urodele amphibians and that of anuran amphibians provide valuable models for studying skin regeneration as adults. Recent progress in transgenesis and genome editing techniques with whole genome sequencing in Xenopus and an axolotl have enabled comparative analyses by molecular genetics of mammal skin and amphibian skin. Such comparative analyses would enable direct comparison of scar-forming myofibroblasts in mammals and blastema-like cells that contribute to skin regeneration in amphibians, ultimately leading to realization of skin regeneration in adult mammals. Amphibian skin regeneration will also be useful for determining how to step up skin regeneration to a higher level of regeneration such as limb regeneration in the future.

Pericytes reduce inflammation and collagen deposition in acute wounds.

BACKGROUND: Pericytes have been shown to have mesenchymal stromal cell-like properties and play a role in tissue regeneration. The goal of this study was to determine whether the addition of a pericyte sheet to a full-thickness dermal wound would enhance the healing of an acute wound. METHODS: Human muscle-derived pericytes and human dermal fibroblasts were formed into cell sheets, then applied to full-thickness excisional wounds on the dorsum of nu/nu mice. Histology was performed to evaluate epidermal and dermal reformation, inflammation and fibrosis. In addition, real-time reverse transcriptase-polymerase chain reaction (RT-PCR) was used to determine cytokine response. RESULTS: Pericytes were detected in the wounds until day 16 but not fibroblasts. Decrease in wound size was noted in pericyte sheet-treated wounds. Enhanced neo-vascularization and healthy granulation tissue formation were noted in the pericyte-treated wounds. Expression of type I collagen messenger RNA (mRNA) was significantly higher in the fibroblast-treated group, whereas Type III collagen mRNA showed significant increase in the pericyte group at days 3, 6 and 9 compared with the fibroblast and no-cell groups. Trichrome staining revealed thick unorganized collagen fibrils in the fibroblast-treated wounds, whereas pericyte-treated wounds contained thinner and more alligned collagen fibrils. Tumor necrosis factor (TNF)-α mRNA levels were increased in the fibroblast-treated wounds compared with pericyte-treated wounds. DISCUSSION: The addition of pericytes may confer beneficial effects to wound healing resulting in reduced recruitment of inflammatory cells and collagen I deposition, potential to enhance wound closure and better collagen alignment promoting stronger tissue.

Fernblock Prevents Dermal Cell Damage Induced by Visible and Infrared A Radiation.

Sun overexposure leads to higher risk of photoaging and skin cancer. The contribution of infrared (IR) and visible light (VIS) radiation is currently being taken into account in their pathogenesis. Erythema, hyperpigmentation, genotoxicity or the increase of matrix metalloproteinases (MMPs) expression are some of the effects induced by these types of radiation. Extracts of various botanicals endowed with antioxidant activity are emerging as new photoprotective compounds. A natural extract from Polypodium leucotomos (Fernblock®, FB) has antioxidant and photoprotective properties and exhibits a strong anti-aging effect. In this study, we evaluated the protective capacity of FB against the detrimental effects of infrared A (IRA) and VIS radiation in human dermal fibroblasts. We analyzed the effects of FB on the morphology, viability, cell cycle and expression of extracellular matrix components of fibroblasts subjected to VIS and IRA. Our results indicate that FB prevents cell damage caused by VIS and IRA. Moreover, it reduces the increase in MMP-1 and cathepsin K expression induced by both VIS and IRA radiation, and curbs alterations in fibrillin 1, fibrillin 2 and elastin expression. All these findings support FB as a feasible approach to prevent or treat skin damage caused by IRA or VIS exposure.

Polydeoxyribonucleotide improves wound healing of fractional laser resurfacing in rat model.

BACKGROUND: Polydeoxyribonucleotide (PDRN) is an active compound that can promote wound healing. PDRN stimulates wound healing by enhancing angiogenesis and increasing fibroblast growth rates. Laser skin resurfacing is a popular cosmetic procedure for skin rejuvenation. Despite excellent improvement of photo-damaged skin and acne scarring, it is accompanied with drawbacks, such as prolonged erythema and crusting. OBJECTIVE: This study was designed to assess the effect of PDRN on wounds induced by fractional laser resurfacing. METHODS: Twelve male rats aged 8 weeks were randomly assigned to the PDRN treatment group and the control group. Wounds were induced using a fractional ablative CO2 laser. The treatment group received daily injections of PDRN and the control group received injections of the vehicle. Wound healing assessed by clinical features and histopathologic findings. RESULTS: The process of wound healing was faster in the treatment group than in the control group. In the histopathological examination, the granulation tissue thickness score of the treatment group was significantly higher than that of the control group. Results of immunohistochemical staining showed a marked increase of VEGF-positive cells and PECAM-1/CD31-positive microvessels in the treatment group. CONCLUSION: PDRN may be a beneficial option to promote wound healing after laser treatment.

FGF2 Overrides TGFß1-Driven Integrin ITGA11 Expression in Human Dermal Fibroblasts.

Deposition of collagen-based extracellular matrix by fibroblasts during wound healing leads to scar formation--a typical outcome of the healing process in soft tissue wounds. The process can, however, be skewed in favor of tissue regeneration by manipulation of wound environment. Low oxygen conditions and supplementation with FGF2 provide extracellular cues that drive wound fibroblasts towards a pro-regenerative phenotype. Under these conditions, fibroblasts dramatically alter expression of many genes among which the most significantly deregulated are extracellular matrix and adhesion molecules. Here we investigate the mechanism of a collagen I binding integrin α11 (ITGA11) deregulation in response to low oxygen-mediated FGF2 effects in dermal fibroblasts. Using RT-PCR, qRT-PCR, Western blotting, and immunocytochemistry, we describe significant down-regulation of ITGA11. Decrease in ITGA11 is associated with its loss from focal adhesions. We show that loss of ITGA11 requires FGF2 induced ERK1/2 activity and in the presence of FGF2, ITGA11 expression cannot be rescued by TGFß1, a potent activator of ITGA11. Our results indicate that FGF2 may be redirecting fibroblasts towards an anti-fibrotic phenotype by overriding TGFß1 mediated ITGA11 expression.

Activation of MRTF-A-dependent gene expression with a small molecule promotes myofibroblast differentiation and wound healing.

Myocardin-related transcription factors (MRTFs) regulate cellular contractility and motility by associating with serum response factor (SRF) and activating genes involved in cytoskeletal dynamics. We reported previously that MRTF-A contributes to pathological cardiac remodeling by promoting differentiation of fibroblasts to myofibroblasts following myocardial infarction. Here, we show that forced expression of MRTF-A in dermal fibroblasts stimulates contraction of a collagen matrix, whereas contractility of MRTF-A null fibroblasts is impaired under basal conditions and in response to TGF-ß1 stimulation. We also identify an isoxazole ring-containing small molecule, previously shown to induce smooth muscle α-actin gene expression in cardiac progenitor cells, as an agonist of myofibroblast differentiation. Isoxazole stimulates myofibroblast differentiation via induction of MRTF-A-dependent gene expression. The MRTF-SRF signaling axis is activated in response to skin injury, and treatment of dermal wounds with isoxazole accelerates wound closure and suppresses the inflammatory response. These results reveal an important role for MRTF-SRF signaling in dermal myofibroblast differentiation and wound healing and suggest that targeting MRTFs pharmacologically may prove useful in treating diseases associated with inappropriate myofibroblast activity.

Versican 3'-untranslated region (3'UTR) promotes dermal wound repair and fibroblast migration by regulating miRNA activity.

Versican is an extracellular chondroitin sulfate proteoglycan which functions as a structural molecule but can also regulate a variety of cellular activities. This study was designed to explore the roles of versican in the process of dermal wound repair. To elevate levels of versican, we ectopically expressed the versican 3'-untranslated region (3'UTR) as a competitive endogenous RNA to modulate expression of versican. We demonstrated that wounds closed faster in transgenic mice expressing the versican 3'UTR, as compared to those in wildtype mice. We stably expressed versican 3'UTR in NIH3T3 fibroblasts and found that the 3'UTR-transfected cells showed increased migratory capacity relative to vector-transfected cells. Interestingly, we found that the 3'UTRs of versican and ß-catenin shared common microRNAs (miRNAs) including miR-185, miR-203*, miR-690, miR-680, and miR-434-3p. Luciferase assays showed that all of these miRNAs could target the 3'UTRs of both versican and ß-catenin, when the luciferase constructs contained fragments harboring the miRNA binding sites. As a consequence, expression of both versican and ß-catenin was up-regulated, which was confirmed in vitro and in vivo. Transfection with small interfering RNAs (siRNAs) targeting the versican 3'UTR abolished the 3'UTR's effects on cell migration and invasion. Taken together, these results demonstrate that versican plays important roles in wound repair and that versican messenger RNAs (mRNAs) could compete with endogenous RNAs for regulating miRNA functions.

Macrophage Wnt-Calcineurin-Flt1 signaling regulates mouse wound angiogenesis and repair.

The treatment of festering wounds is one of the most important aspects of medical care. Macrophages are important components of wound repair, both in fending off infection and in coordinating tissue repair. Here we show that macrophages use a Wnt-Calcineurin-Flt1 signaling pathway to suppress wound vasculature and delay repair. Conditional mutants deficient in both Wntless/GPR177, the secretory transporter of Wnt ligands, and CNB1, the essential component of the nuclear factor of activated T cells dephosporylation complex, displayed enhanced angiogenesis and accelerated repair. Furthermore, in myeloid-like cells, we show that noncanonical Wnt activates Flt1, a naturally occurring inhibitor of vascular endothelial growth factor-A-mediated angiogenesis, but only when calcineurin function is intact. Then, as expected, conditional deletion of Flt1 in macrophages resulted in enhanced wound angiogenesis and repair. These results are consistent with the published link between enhanced angiogenesis and enhanced repair, and establish novel therapeutic approaches for treatment of wounds.

Nucleolin enhances the proliferation and migration of heat-denatured human dermal fibroblasts.

Denatured dermis, a part of dermis in burned skin, has the ability to restore its normal morphology and functions after their surrounding microenvironment is improved. However, the cellular and molecular mechanisms by which the denatured dermis could improve wound healing are still unclear. This study aimed to investigate the role of nucleolin during the recovery of heat-denatured human dermal fibroblasts. Nucleolin mRNA and protein expression were significantly increased time-dependently during the recovery of heat-denatured human dermal fibroblasts (52 °C, 30 seconds). Heat-denaturation promoted a time-dependent cell proliferation, migration, chemotaxis, and scratched wound healing during the recovery of human dermal fibroblasts. These effects were prevented by knockdown of nucleolin expression with small interference RNA (siRNA), whereas overexpression of nucleolin enhanced cell proliferation, migration, and chemotaxis of human dermal fibroblasts with heat-denaturation. In addition, the expression of transforming growth factor-beta 1(TGF-ß1) was significantly increased during the recovery of heat-denatured dermis and human dermal fibroblasts. TGF-ß1 expression was up-regulated by nucleolin in human dermal fibroblasts. The results suggest that nucleolin expression is up-regulated, and play an important role in promoting cell proliferation, migration, and chemotaxis of human dermal fibroblasts during the recovery of heat-denatured dermis with a mechanism probably related to TGF-ß1.

Improved repair of dermal wounds in mice lacking microRNA-155.

Wound healing is a well-regulated but complex process that involves haemostasis, inflammation, proliferation and maturation. Recent reports suggest that microRNAs (miRs) play important roles in dermal wound healing. In fact, miR deregulation has been linked with impaired wound repair. miR-155 has been shown to be induced by inflammatory mediators and plays a central regulatory role in immune responses. We have investigated the potential role of miR-155 in wound healing. By creating punch wounds in the skin of mice, we found an increased expression of miR-155 in wound tissue when compared with healthy skin. Interestingly, analysis of wounds of mice lacking the expression of miR-155 (miR-155(-/-) ) revealed an increased wound closure when compared with wild-type animals. Also, the accelerated wound closing correlated with elevated numbers of macrophages in wounded tissue. Gene expression analysis of wounds tissue and macrophages isolated from miR-155(-/-) mice that were treated with interleukin-4 demonstrated an increased expression of miR-155 targets (BCL6, RhoA and SHIP1) as well as, the finding in inflammatory zone-1 (FIZZ1) gene, when compared with WT mice. Moreover, the up-regulated levels of FIZZ1 in the wound tissue of miR-155(-/-) mice correlated with an increased deposition of type-1 collagens, a phenomenon known to be beneficial in wound closure. Our data indicate that the absence of miR-155 has beneficial effects in the wound healing process.

Activity of imipenem against Klebsiella pneumoniae biofilms in vitro and in vivo.

Encapsulated Klebsiella pneumoniae has emerged as one of the most clinically relevant and more frequently encountered opportunistic pathogens in combat wounds as the result of nosocomial infection. In this report, we show that imipenem displayed potent activity against established K. pneumoniae biofilms under both static and flow conditions in vitro. Using a rabbit ear model, we also demonstrated that imipenem was highly effective against preformed K. pneumoniae biofilms in wounds.

Microencapsulated VEGF gene-modified umbilical cord mesenchymal stromal cells promote the vascularization of tissue-engineered dermis: an experimental study.

BACKGROUND AIMS: Tissue-engineered dermis (TED) is thought to be the best treatment for skin defect wounds; however, lack of vascular structures in these products can cause slow vascularization or even transplant failure. We assessed the therapeutic potential of microencapsulated human umbilical cord mesenchymal stromal cells (hUCMSCs) expressing vascular endothelial growth factor (VEGF) in vascularization of TED. METHODS: hUCMSCs were isolated by means of enzymatic digestion and identified by means of testing biological characteristics. hUCMSCs were induced to differentiate into dermal fibroblasts in conditioned induction media. Collagen-chitosan laser drilling acellular dermal matrix (ADM) composite scaffold was prepared by means of the freeze dehydration and dehydrothermal cross-linking method. hUCMSC-derived fibroblasts were implanted on composite scaffolds to construct TED. TED with microencapsulated VEGF gene-modified hUCMSCs was then transplanted into skin defect wounds in pigs. The angiogenesis of TED at 1 week and status of wound healing at 3 weeks were observed. RESULTS: The collagen-chitosan laser ADM composite has a uniform microporous structure. This composite has been used to grow hUCMSC-derived fibroblasts in vitro and to successfully construct stem cell-derived TED. Microencapsulated VEGF gene-modified hUCMSCs were prepared with the use of a sodium alginate-barium chloride one-step encapsulation technology. Seven days after the transplantation of the stem cell-derived TED and microencapsulated VEGF gene-modified hUCMSCs into the skin defect wounds on the backs of miniature pigs, the VEGF expression increased and the TED had a higher degree of vascularization. Re-epithelialization of the wound was completed after 3 weeks. CONCLUSIONS: Microencapsulated VEGF gene-modified hUCMSCs can effectively improve the vascularization of TED and consequently the quality of wound healing.

Pulsed electromagnetic fields (PEMF) promote early wound healing and myofibroblast proliferation in diabetic rats.

Reduced collagen deposition possibly leads to slow recovery of tensile strength in the healing process of diabetic cutaneous wounds. Myofibroblasts are transiently present during wound healing and play a key role in wound closure and collagen synthesis. Pulsed electromagnetic fields (PEMF) have been shown to enhance the tensile strength of diabetic wounds. In this study, we examined the effect of PEMF on wound closure and the presence of myofibroblasts in Sprague-Dawley rats after diabetic induction using streptozotocin. A full-thickness square-shaped dermal wound (2 cm × 2 cm) was excised aseptically on the shaved dorsum. The rats were randomly divided into PEMF-treated (5 mT, 25 Hz, 1 h daily) and control groups. The results indicated that there were no significant differences between the groups in blood glucose level and body weight. However, PEMF treatment significantly enhanced wound closure (days 10 and 14 post-wounding) and re-epithelialization (day 10 post-wounding), although these improvements were no longer observed at later stages of the wound healing process. Using immunohistochemistry against α-smooth muscle actin (α-SMA), we demonstrated that significantly more myofibroblasts were detected on days 7 and 10 post-wounding in the PEMF group when compared to the control group. We hypothesized that PEMF would increase the myofibroblast population, contributing to wound closure during diabetic wound healing.