Remodeling Phase Research Articles

Real-time OXPHOS capacity analysis in wounded skin from diabetic mice: A pilot study.

Diabetes mellitus (DM) impairs wound healing. The aim was to determine whether DM influences mitochondrial respiration in wounded skin (WS) and non-wounded skin (NWS), in a pre-clinical wound healing model of streptozotocin (STZ)-induced diabetes. Six weeks after diabetes induction, two wounds were created in the back of C57BL/J6 mice. Using high-resolution respirometry (HRR), oxygen flux was measured, in WS and NWS, using two substrate-uncoupler-inhibitor titration protocols, at baseline (day 0), day 3 and 10 post-wounding, in STZ-DM and non-diabetic (NDM) mice. Flux control ratios for the oxidative phosphorylation (OXPHOS) capacity were calculated. A significant increase in mitochondrial respiration was observed in STZ-DM skin compared to control skin at baseline. The OXPHOS capacity was decreased in WS under diabetes at day 3 post-wounding (inflammation phase). However, at day 10 post-wounding (remodeling phase), the OXPHOS capacity was higher in WS from STZ-DM compared to NDM mice, and compared to NWS from STZ-DM mice. A significant relative contribution of pyruvate, malate and glutamate (PMG) oxidation to the OXPHOS capacity was observed in WS compared to NWS from STZ-DM mice, at day 10, while the relative contribution of fatty acid oxidation to the OXPHOS capacity was higher in NWS. The OXPHOS capacity is altered in WS from STZ-DM compared to NDM mice across the healing process, and so is the substrate contribution in WS and NWS from STZ-DM mice, at each time point. HRR may be a sensitive tool to evaluate the underlying mechanisms of tissue repair during wound healing.

Graft-Host Interaction and Its Effect on Wound Repair Using Mouse Models.

Autologous skin grafting has been commonly used in clinics for decades to close large wounds, yet the cellular and molecular interactions between the wound bed and the graft that mediates the wound repair are not fully understood. The aim of this study was to better understand the molecular changes in the wound triggered by autologous and synthetic grafting. Defining the wound changes at the molecular level during grafting sets the basis to test other engineered skin grafts by design. In this study, a full-thickness skin graft (SKH-1 hairless) mouse model was established. An autologous full-thickness skin graft (FTSG) or an acellular fully synthetic Biodegradable Temporising Matrix (BTM) was grafted. The wound bed/grafts were analysed at histological, RNA, and protein levels during the inflammation (day 1), proliferation (day 5), and remodelling (day 21) phases of wound repair. The results showed that in this mouse model, similar to others, inflammatory marker levels, including Il-6, Cxcl-1, and Cxcl-5/6, were raised within a day post-wounding. Autologous grafting reduced the expression of these inflammatory markers. This was different from the wounds grafted with synthetic dermal grafts, in which Cxcl-1 and Cxcl-5/6 remained significantly high up to 21 days post-grafting. Autologous skin grafting reduced wound contraction compared to wounds that were left to spontaneously repair. Synthetic grafts contracted significantly more than FTSG by day 21. The observed wound contraction in synthetic grafts was most likely mediated at least partly by myofibroblasts. It is possible that high TGF-β1 levels in days 1-21 were the driving force behind myofibroblast abundance in synthetic grafts, although no evidence of TGF-β1-mediated Connective Tissue Growth Factor (CTGF) upregulation was observed.

The importance of BMPs and TGF-βs for endochondral bone repair – A longitudinal study in hip arthroplasty patients

IntroductionOsseointegration of hip implants, although a decade-long process, shows striking similarities with the four major phases of endochondral bone repair. In the current study we investigated the spatiotemporal involvement of bone morphogenic proteins (BMPs) and transforming growth factor betas (TGF-βs) throughout the process of bone repair leading to successfully osseointegrated hip implants. Materials and methodsTwenty-four patients that had undergone primary total hip arthroplasty (THA) due to one-sided osteoarthritis (OA) were investigated during a period of 18 years (Y) with repeated measurements of plasma biomarkers as well as clinical and radiological variables. All implants were clinically and radiographically well anchored throughout the follow-up. Eighty-one healthy donors divided in three gender- and age-matched groups and twenty OA patients awaiting THA, served as controls. Plasma was analyzed for BMP-1, -2, -3, -4, -6, -7 -9 and TGF-β1, -β2, -β3 by use of a high-sensitivity and wide dynamic range electrochemiluminescence technique allowing for detection of minor changes. ResultsSpatiotemporal changes during the follow-up are presented in the context of the four phases of endochondral bone repair shown in earlier studies and transposed to the current study based on similarities in biomarker responses. Phase 1: Primary proinflammatory phase lasting from surgery until day 7, Phase 2: Chondrogenic phase from day 7 until 18 months postsurgery, Phase 3: Secondary proinflammatory and cartilage remodeling phase lasting from 18 months until 7Y, Phase 4: coupled bone remodeling from 7Y until 18Y postsurgery. BMP-1 increased sharply shortly after surgery and remained significantly above healthy during the chondrocyte recruitment, proliferation, and hypertrophy phases with a subsequent return to control level at 5Y postsurgery. BMP-2 was above healthy controls before surgery and 1 day after surgery before decreasing to control level and remaining there throughout the follow-up. BMP-3 was at control level from presurgery until 6M after surgery when it increased to a peak at 2Y during the cartilage hypertrophy phase followed by a gradual decrease to control level at 10Y during the phase of bone formation. In the following, BMP-3 decreased below controls to a nadir 15Y postsurgery during coupled bone remodeling. BMP-4 was at control level from presurgery until 10Y postsurgery when it increased to a sharp peak at 15Y after surgery followed by a return to the level of healthy at 18Y. BMP-6 did not differ from healthy during the follow-up. BMP-7 was at control level from presurgery until 1Y postsurgery before gradually increasing to a peak at 10Y during the early phase of osteogenesis with a gradual return to control level at 18Y during the phase of coupled bone remodeling. BMP-9 was above OA before surgery followed by a decrease to basal level on day 1 after surgery and a renewed increase to a plateau above controls lasting from 6 W until returning to the level of healthy at 18Y postsurgery, i.e., throughout the phases of cartilage formation, cartilage hypertrophy and remodeling, bone formation and coupled bone remodeling. TGF-β1 was above controls presurgery before decreasing to baseline shortly after surgery followed by a renewed increase at 6 M to a peak at 2Y during cartilage hypertrophy/remodeling followed by a gradual return to baseline at 10Y during early osteoblastogenesis. TGF-β2 was at control level from presurgery until the phase of cartilage remodeling at 5Y when it increased sharply to a peak at 7Y with a gradual return to baseline at 18Y postsurgery. TGF-β3 remained at control level throughout the study. ConclusionThis study shows that the involvement of BMPs and TGF-βs in endochondral bone repair is a process of stepwise recruitment of individual biomarkers characterized by distinct, yet overlaping, spatiotemporal patterns that extend from the early phase of pre-chondrocyte recruitment until the late phase of coupled bone remodeling.

Metallic elements combine with herbal compounds upload in microneedles to promote wound healing: a review.

Wound healing is a dynamic and complex restorative process, and traditional dressings reduce their therapeutic effectiveness due to the accumulation of drugs in the cuticle. As a novel drug delivery system, microneedles (MNs) can overcome the defect and deliver drugs to the deeper layers of the skin. As the core of the microneedle system, loaded drugs exert a significant influence on the therapeutic efficacy of MNs. Metallic elements and herbal compounds have been widely used in wound treatment for their ability to accelerate the healing process. Metallic elements primarily serve as antimicrobial agents and facilitate the enhancement of cell proliferation. Whereas various herbal compounds act on different targets in the inflammatory, proliferative, and remodeling phases of wound healing. The interaction between the two drugs forms nanoparticles (NPs) and metal-organic frameworks (MOFs), reducing the toxicity of the metallic elements and increasing the therapeutic effect. This article summarizes recent trends in the development of MNs made of metallic elements and herbal compounds for wound healing, describes their advantages in wound treatment, and provides a reference for the development of future MNs.

Mechanical bone strength decreases considerably after microwave ablation-Ex-vivo and in-vivo analysis in sheep long bones.

Bone metastases are on the rise due to longer survival of cancer patients. Local tumor control is required for pain relief. Microwave ablation (MWA) is a technique for minimally invasive local tumor treatment. Tumor tissue is destroyed by application of local hyperthermia to induce necrosis. Given the most common setting of palliative care, it is generally considered beneficial for patients to start mobilizing directly following treatment. No data on mechanical strength in long bones after MWA have been published so far. In- and ex-vivo experiments on sheep tibias were performed with MWA in various combinations of settings for time and power. During the in-vivo part sheep were sacrificed one or six weeks after ablation. Mechanical strength was examined with a three-point bending test for ablations in the diaphysis and with an indentation test for ablations in the metaphysis. MWA does not decrease mechanical strength in the diaphysis. In the metaphysis strength decreased up to 50% six weeks after ablation, which was not seen directly after ablation. MWA appears to decrease mechanical strength in long bone metaphysis up to 50% after six weeks, however strength remains sufficient for direct mobilization. The time before normal strength is regained after the remodeling phase is not known.

Distinct defects in early innate and late adaptive immune responses typify impaired fracture healing in diet-induced obesity.

Bone fractures, the most common musculoskeletal injuries, heal through three main phases: inflammatory, repair, and remodeling. Around 10% of fracture patients suffer from impaired healing that requires surgical intervention, a huge burden on the healthcare system. The rate of impaired healing increases with metabolic diseases such as obesity-associated hyperglycemia/type 2 diabetes (T2D), an increasing concern given the growing incidence of obesity/T2D. Immune cells play pivotal roles in fracture healing, and obesity/T2D is associated with defective immune-cell functions. However, there is a gap in knowledge regarding the stoichiometry of immune cells that populate the callus and how that population changes during different phases of healing. Here, we used complementary global and single-cell techniques to characterize the repertoire of immune cells in the fracture callus and to identify populations specifically enriched in the fracture callus relative to the unfractured bone or bone marrow. Our analyses identified two clear waves of immune-cell infiltration into the callus: the first wave occurs during the early inflammatory phase of fracture healing, while the second takes place during the late repair/early remodeling phase, which is consistent with previous publications. Comprehensive analysis of each wave revealed that innate immune cells were activated during the early inflammatory phase, but in later phases they returned to homeostatic numbers and activation levels. Of the innate immune cells, distinct subsets of activated dendritic cells were particularly enriched in the inflammatory healing hematoma. In contrast to innate cells, lymphocytes, including B and T cells, were enriched and activated in the callus primarily during the late repair phase. The Diet-Induced Obesity (DIO) mouse, an established model of obesity-associated hyperglycemia and insulin resistance, suffers from multiple healing defects. Our data demonstrate that DIO mice exhibit dysregulated innate immune responses during the inflammatory phase, and defects in all lymphocyte compartments during the late repair phase. Taken together, our data characterize, for the first time, immune populations that are enriched/activated in the callus during two distinct phases of fracture healing and identify defects in the healing-associated immune response in DIO mice, which will facilitate future development of immunomodulatory therapeutics for impaired fracture healing.

Myocardial Remodeling in Early Chronic Kidney Disease—Mineral and Bone Disorder Model with Low Bone Turnover

Chronic kidney disease—mineral and bone disorder (CKD-MBD) plays a significant role in causing cardiovascular morbidity and mortality related to CKD. CKD-MBD has been studied during advanced stages when changes in inorganic phosphate (Pi) and its hormonal regulation are obvious. The initial phases of myocardial remodeling (MR) in early CKD-MBD remain poorly understood. We induced mild CKD-MBD in spontaneously hypertensive rats using 3/4 nephrectomy. Animals were fed standard chow, containing 0.6% phosphate. In each animal, we analyzed indices of chronic kidney injury, bone turnover and Pi exchange, and assessed the myocardial histology and gene expression profile. Applied CKD-MBD models corresponded to human CKD S1-2 with low bone turnover and without an increase in systemic Pi-regulating factors (parathyroid hormone and fibroblast growth factor 23). In mild CKD-MBD models, we found MR features characterized by cardiomyocyte hypertrophy, interstitial and perivascular fibrosis, intramyocardial artery media thickening, along with alterations in Ppp3ca, Mapk1, Jag1, Hes1, Ptch1, Numb, Lgr4 and Bmp4 genes. Among other genes, the down-regulation of Jag1 was most tightly associated with either myocardial hypertrophy or fibrosis. Myocardial alterations concurrently occurred with mild CKD-MBD and comprised fibrosis preceding cardiomyocyte hypertrophy. The histological features of MR were associated with myocardial P accumulation in settings of low bone turnover, prior to a response of systemic Pi-regulating factors and with alterations in calcineurin, ERK1/2, Notch, BMP and Hedgehog genes.

Immunohistochemical evaluation of tissues following bone implant extraction from upper and lower limb.

Fractured bones can regenerate and restore their biological and mechanical properties to the state prior to the damage. In some cases, however, the treatment of fractures requires the use of supportive implants. For bone healing, three processes are essential: the inflammatory phase, the repair phase and the remodelling phase. A proper course of the first - inflammatory - stage is important to ensure a successful fracture healing process. In our study, we evaluated tissue samples immunohistochemically from the area surrounding the fractures of upper and lower limbs (bone tissue, soft tissue, and the implant-adhering tissue) for markers: CD11b, CD15, CD34, CD44, CD68, Cathepsin K, and TRAcP that are linked to the aforementioned phases. In soft tissue, higher expressions of CD68, CD34, CD15 and CD11b markers were observed than in other locations. TRAcP and Cathepsin K markers were more expressed in the bone tissue, while pigmentation, necrosis and calcification were more observed in the implant-adhering tissue. Since even the implant materials commonly perceived as inert elicit the observed inflammatory responses, new surface treatments and materials need to be developed.

Wound healing and soft tissue regeneration. Literature review

The publication provides data from literary sources on the course of reparative processes in soft tissues and healing of skin wounds. The largest organ of the human body is the skin. It performs many extremely important functions. After traumatic damage to the skin, a complex cascade of cellular reactions occurs, which is unique in its nature. Since healing and regeneration processes occur in all parts of the human body, this review focuses on the processes of reparative changes in the skin. The first stage of acute wound healing is devoted to hemostasis and the formation of the previous wound matrix, which occurs immediately after the injury and ends in a few hours. In addition, this phase triggers the processes of an inflammatory reaction, the expressiveness of which depends on individual reactivity, the degree of microbial contamination of the wound, the type and nature of the lesion. Then, the proliferation phase begins, at this stage there is restoration of the wound surface, formation of granulation tissue and restoration of the vasculature. The third and final stage of wound healing is the remodeling phase, which usually begins 2-3 weeks after tissue damage. During this phase, the vessels of the granulation tissue are emptied, the number of fibroblasts sharply decreases, but instead, the number of elastic and, especially, collagen fibers increases. The continuous synthesis and destruction of collagen has the effect of remodeling the mature wound matrix for approximately 6 months after injury. At this stage, the formation and degradation of collagen balance each other, and there are no significant changes in its amount. The remodeling phase is most responsible for the volume of scar tissue formed. The aim of the work is to systematize the current literature data on the healing of soft tissue wounds. Conclusion. The analysis of the given data from the scientific literature shows that the regeneration of soft tissues is a complex process of body reactions that leads to the formation of scar tissue. Many pathophysiological processes underlying reparative reactions are still unknown.

Three‐Step Regenerative Strategy: Multifunctional Bilayer Hydrogel for Combined Photothermal/Photodynamic Therapy to Promote Drug‐Resistant Bacteria‐Infected Wound Healing

AbstractThe drug‐resistant bacterial‐infected skin wound is still a severe healthcare problem. Uncontrolled bacterial infection, abundant reactive oxygen species (ROS) content, and prolonged inflammatory response are detrimental to wound healing. Moreover, excessive vessel growth can result in unsatisfactory scar formation. Herein, a three‐step regenerative strategy based on a bilayered gelatin/acryloyl β‐cyclodextrin (BGACD) hydrogel containing physical host–guest complexations and chemical crosslinks is proposed. The hydrogel is loaded with humic acids (HAs) and astragaloside IV (AS) in the lower layer and verteporfin (Vt) in the upper layer. Different gelatin/acryloyl β‐cyclodextrin ratios endow the lower and upper layers of the hydrogel with different degradation rates. Under light irradiation, the combination of HAs‐induced photothermal therapy (PTT) and verteporfin‐induced photodynamic therapy effectively inhibits MRSA growth. The HAs and astragaloside IV are released from the lower layer to scavenge ROS and promote M2 macrophage polarization and angiogenesis during the inflammation and early proliferation phases, while verteporfin releases from the upper layer suppress excessive vessel growth during the late proliferation and remodeling phases. The HAs‐AS@Vt@BGACD hydrogel successfully achieves rapid and scarless wound healing in an MRSA‐infected wound model in rats. Therefore, the HAs‐AS@Vt@BGACD hydrogel shows promising potential for the treatment of drug‐resistant bacteria‐infected skin wound healing.

Crosslinked Collagen-Hyaluronic Acid Scaffold Enhances Interleukin-10 Under Co-Culture of Macrophages And Adipose-Derived Stem Cells.

The skin, the human body's largest organ, possesses a protective barrier that renders it susceptible to various injuries, including burns. Following burn trauma, the inflammatory process triggers both innate and adaptive immune responses, leading to the polarization of macrophages into two distinct phenotypes: the pro-inflammatory M1 and the anti-inflammatory M2. This dual response sets the stage for wound healing and subsequent tissue regeneration. Contributing to this transition from M1 to M2 polarization are human adipose-derived stem cells (ASCs), which employ paracrine signaling and inflammation suppression to enhance the remodeling phase. ASCs, when combined with biocompatible polymers, can be integrated into functional scaffolds. This study introduces an 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide-crosslinked (EDC-crosslinked) collagen-hyaluronic acid(Col-HA) scaffold assembled with ASCs, designed as a natural biomaterial device to modulate macrophage behavior in vitro under co-culture conditions. This innovation aims to improve wound healing processes. The EDC-crosslinked Col-HA scaffold favored the release of anti-inflammatory cytokines by ASCs, which indicated the M2 prevalence. In tissue engineering, a critical objective lies in the development of functional biomaterials capable of guiding specific tissue responses, notably the control of inflammatory processes. Thus, this research not only presents original findings but also points toward a promising avenue within regenerative medicine.

Versatile Hydrogel Dressings That Dynamically Regulate the Healing of Infected Deep Burn Wounds.

Severe burns threaten patient lives due to pain, inflammation, bacterial infection, and scarring. Most burn dressings that are commonly used perform a single function and are not well suited for the management of deep burns. Therefore, a multifunctional antimicrobial peptide- and stem cell-loaded macroporous hydrogel that can fight bacterial infection and regulate wound healing progression by temporally regulating cytokine production by internal stem cells is developed. The macroporous skeletal hydrogel is manufactured via the cryogenic gelation of hyaluronic acid (cryogel). Based on the oxidative polymerization reaction of dopamine, the antimicrobial peptide DP7 is immobilized on the surface of the cryogel (DA7CG). Placental mesenchymal stem cells (PMSCs) are then packaged inside the macroporous hydrogel (DA7CG@C). According to the results of in vitro and in vivo experiments, during the inflammatory phase, DP7 inhibits infection and modulates inflammation; during the proliferative phase, DA7CG@C accelerates the regeneration of skin, blood vessels, and hair follicles via internal stem cells; and during the remodeling phase, DA7CG@C contributes to extracellular matrix remodeling due to the ability of DP7 to regulate the paracrine secretion of PMSCs, synergistically promoting scar-free healing. DA7CG@C can participate in all phases of wound healing; therefore, it is a promising dressing for burn treatment.

Segmental and transmural motion of the rat myocardium estimated using quantitative ultrasound with new strategies for infarct detection.

Introduction: The estimation of myocardial motion abnormalities has great potential for the early diagnosis of myocardial infarction (MI). This study aims to quantitatively analyze the segmental and transmural myocardial motion in MI rats by incorporating two novel strategies of algorithm parameter optimization and transmural motion index (TMI) calculation. Methods: Twenty-one rats were randomly divided into three groups (n = 7 per group): sham, MI, and ischemia-reperfusion (IR) groups. Ultrasound radio-frequency (RF) signals were acquired from each rat heart at 1 day and 28 days after animal model establishment; thus, a total of six datasets were represented as Sham1, Sham28, MI1, MI28, IR1, and IR28. The systolic cumulative displacement was calculated using our previously proposed vectorized normalized cross-correlation (VNCC) method. A semiautomatic regional and layer-specific myocardium segmentation framework was proposed for transmural and segmental myocardial motion estimation. Two novel strategies were proposed: the displacement-compensated cross-correlation coefficient (DCCCC) for algorithm parameter optimization and the transmural motion index (TMI) for quantitative estimation of the cross-wall transmural motion gradient. Results: The results showed that an overlap value of 80% used in VNCC guaranteed a more accurate displacement calculation. Compared to the Sham1 group, the systolic myocardial motion reductions were significantly detected (p < 0.05) in the middle anteroseptal (M-ANT-SEP), basal anteroseptal (B-ANT-SEP), apical lateral (A-LAT), middle inferolateral (M-INF-LAT), and basal inferolateral (B-INF-LAT) walls as well as a significant TMI drop (p < 0.05) in the M-ANT-SEP wall in the MI1 rats; significant motion reductions (p < 0.05) were also detected in the B-ANT-SEP and A-LAT walls in the IR1 group. The motion improvements (p < 0.05) were detected in the M-INF-LAT wall in the MI28 group and the apical septal (A-SEP) wall in the IR28 group compared to the MI1 and IR1 groups, respectively. Discussion: Our results show that the MI-induced reductions and reperfusion-induced recovery in systolic myocardial contractility could be successfully evaluated using our method, and most post-MI myocardial segments could recover systolic function to various extents in the remodeling phase. In conclusion, the ultrasound-based quantitative estimation framework for estimating segmental and transmural motion of the myocardium proposed in our study has great potential for non-invasive, novel, and early MI detection.

Tea polyphenols (TPP) as a promising wound healing agent: TPP exerts multiple and distinct mechanisms at different phases of wound healing in a mouse model

Polyphenols have been widely used to treat various chronic skin diseases because they are beneficial in wound healing and show anti-inflammatory effects, however, the mechanism of action remains ambiguous. Previously, we reported the wound healing capability of tea polyphenols (TPP), the major functional component of tea, in vivo. The current study aimed to address the mechanisms of TPP in wound healing during different phases (inflammation, proliferation and remodeling). During the inflammation phase, TPP reduced the production of proinflammatory cytokines (IL-1β, IL-6 and TNF-α) and inhibited infiltration of neutrophils; during the proliferation phase, TPP promoted the expression of growth factor VEGF-A, which can promote vascular endothelial cell division and induce angiogenesis; TPP improved the morphology of the wound and restored the ratio of type III/I collagens during the remodeling phase, as determined by Masson-trichrome staining and Sirius red staining assays. By tracking the changes in the wound area, TPP and recombinant human epidermal growth factor (rhEGF), rather than povidone-iodine (PVP-I), were able to promote wound healing. These results suggest that TPP plays a pivotal role in all the key stages of wound healing and displays distinct mechanisms from rhEGF, suggesting clinical significance for the future application of TPP as a natural wound healing agent.

Fish Skin Graft: Narrative Review and First Application for Abdominal Wall Dehiscence in Children.

Acellular fish skin grafts (FSGs) are tissue-based products created by minimally processing the skin of the Atlantic cod (Gadus morhua). The FSG is rich in omega-3 and facilitates tissue regeneration by supporting revascularization and ingrowth in the proliferation and remodeling phases of wound healing. FSG is structurally more similar to human skin than antiviral-processed skin substitutes such as amniotic membrane, and there are no known prion, bacterial, or viral diseases that can be transmitted from North-Atlantic cod to humans. The FSG is processed using a proprietary method that preserves the structure and lipid composition of the skin. FSG is CE marked, and US Food and Drug Administration cleared for multiple clinical applications in partial and full-thickness wounds. FSG is currently the only acellular dermal matrix product that does not originate from mammalian tissues. For this narrative review, Medline and UpToDate were used to include a total of 21 articles published from 2015 to 2022 about fish skin graft use. We also reported a case of a 7-year-old boy who underwent treatment with FSG for abdominal wall dehiscence at our department of pediatric surgery, IRCCS Sant'Orsola-Malpighi, Alma Mater Studiorum, University of Bologna, University Hospital of Bologna. FSG provides a valuable and sustainable treatment that improves wound healing in both adult and pediatric populations. We described the first application of an FSG for wound dehiscence of the abdominal wall in a pediatric patient, reporting how FSG was completely reabsorbed and improved the skin's repair.

Inhibition of the CoREST Repressor Complex Promotes Wound Re-Epithelialization through the Regulation of Keratinocyte Migration

Wound healing is a complex process involving phases of hemostasis, inflammation, proliferation, and remodeling. The regenerative process in the skin requires coordination between many regulators, including signaling molecules, transcription factors, and the epigenetic machinery. In this study, we show that chromatin regulators HDAC1 and LSD1, key components of the CoREST repressor complex, are upregulated in the regenerating epidermis during wound repair. We also show that corin, a synthetic dual inhibitor of the CoREST complex and HDAC1/LSD1 activities, significantly accelerates wound closure through enhanced re-epithelialization in a mouse tail wound model. Acetylated H3K9 (methylation of histone H3 at lysine 9) expression, a histone modification targeted by HDAC1, is increased in keratinocytes after topical treatment with 100 nM and 1 μM of corin. Invitro experiments demonstrate that corin promotes migration and inhibits the proliferation of human keratinocytes. Furthermore, expression levels of genes promoting keratinocyte migration, such as AREG, CD24, EPHB2, ITGAX, PTGS, SCT1, SERPINB2, SERPINE1, SLPI, SNAI2, and TWIST, increased in keratinocytes treated with corin. These data demonstrate that dual inhibition of class I histone deacetylases and LSD1 by corin may serve as a new approach for promoting wound re-epithelialization and provide a platform for further applications of corin for the treatment of chronic wounds.

A Biomimetic Adhesive and Robust Janus Patch with Anti-Oxidative, Anti-Inflammatory, and Anti-Bacterial Activities for Tendon Repair.

Early stage oxidative stress, inflammatory response, and infection after tendon surgery are highly associated with the subsequent peritendinous adhesion formation, which may diminish the quality and function of the repaired tendon. Although various anti-inflammatory and/or antibacterial grafts have been proposed to turn the scale, most of them suffer from the uncertainty of drug-induced adverse effects, low mechanical strength, and tissue adhesiveness. Here, inspired by the tendon anatomy and pathophysiology of adhesion development, an adhesive and robust dual-layer Janus patch is developed, whose inner layer facing the operated tendon is a multifunctional electrospun hydrogel patch (MEHP), encircled further by a poly-l-lactic acid (PLLA) fibrous outer layer facing the surrounding tissue. Specifically, MEHP is prepared by gelatin methacryloyl (GelMA) and zinc oxide (ZnO) nanoparticles, which are co-electrospun first and then treated by tannic acid (TA). The inner MEHP exhibits superior mechanical performance, adhesion strength, and outstanding antioxidation, anti-inflammation, and antibacterial properties, and it can adhere to the injury site offering a favorable microenvironment for tendon regeneration. Meanwhile, the outer PLLA acts as a physical barrier that prevents extrinsic cells and tissues from invading the defect site, reducing peritendinous adhesion formation. This work presents a proof-of-concept of a drug-free graft with anisotropic adhesive and biological functions to concert the healing phases of injured tendon by alleviating incipient inflammation and oxidative damage but supporting tissue regeneration and reducing tendon adhesion in the later phase of repair and remodeling. It is envisioned that this Janus patch could offer a promising strategy for safe and efficient tendon therapy.

The Effect of Platelet Rich Plasma versus MSCs Derived Exosomes on the Healing of Burn Injury in Albino Rat: Histological Study

Abstract Background The clinical treatment of skin loss due to severe and massive burns or wounds continues to be a major problem in surgical procedures. Although different kinds of dressings and therapies have been developed, but most of them are expensive. Therefore, new strategies are needed to promote and help in wound healing and repair. Recent studies have demonstrated that exosomes help tissue repair because of high stability, non immune rejection and easy control of dosage and concentration. Platelet-rich plasma (PRP) is an autologous concentration of platelets in concentrated plasma. It has been used to promote soft and hard tissue healing. Aim to compare the effect of MSCs derived exosomes versus PRP on the promotion of healing of experimentally induced second degree partial thickness burn injury in adult male albino rats. Methods The thirty-two adult male albino rats were divided randomly into 4 groups. Group I (control). Group II (burn injury group) that will be left for spontaneous healing. Group III (burn injury treated with PRP intradermal injection). Group IV (burn injury treated with intradermal MSCs derived exosome). All the animals were sacrificed at 7th day (subgroup a) and 21th day (subgroup b). The skin biopsies will be taken and processed for light microscope examination. Results H&amp;E stained section of untreated burn (subgroup IIa) showed coagulative necrosis in epidermis and papillary layer of the dermis. Sign of epithelial migration from the edge of the wound appeared. In Subgroup IIb the surface of the wound was covered by an eschar that converted partial thickness into complete thickness. This resulted in formation of granulation tissue in the dermis. In Subgroup IIIa showed the formation of thin layer of epidermis containing undifferentiated keratinocytes. The underlying dermis contained collagen fibers and beginning of new hair follicles formation. Some specimens in Subgroup IIIb revealed thin epidermis with incomplete differentiation of keratinocytes. Numerous hair follicles were detected in the dermis. However some specimens showed thickened epidermis with presence of rete ridges. The dermis showed few irregularly distributed collagen fibers in granulation tissue with absence of skin appendages. In exosome treated group (subgroup IVa) showed thin epidermis with well differentiated keratinocytes. The dermis contained collagen fibers with absence of skin appendages. Subgroup IVb was more or less similar to the control group. Conclusion The current study revealed that burn treated exosomes group was better than PRP treated group. In addition PRP treated group revealed hyperplastic changes in epidermis with delay in remodeling phase of burn healing.

Effects of Broccoli Extract (Brassica oleracea var. italica) on Collagen Images in Wounds: Experimental Study in Wistar Rats (Rattus norvegicus)

ABSTRACTIntroduction: Wound healing is a protective function of the body that focuses on quick recovery where the regeneration process in a hostile environment takes more time. In particular, the oral cavity is a remarkable environment in which wound healing occurs in warm oral fluid that contains millions of microorganisms. Collagen plays an important role in all phases of wound healing, which provides integrity and strength to tissues and it is very important especially in the proliferation and remodeling phases. One of the materials that have potential related to collagen is broccoli (Brassica oleracea var.italica). Broccoli has a potential to regulate collagen, therefore it could be an alternative to answer the problem related to antiinflammatory, antioxidant, and antimicrobial effects. The aim of this research with experimental design is to study the potential effects of broccoli extract on the representation of collagen image in wounds.Methods: This research used 18 male wistar rats by making incision on each of the rats’ back. These rats are divided into two groups, control group which get no treatment, and treatment group which is treated by applying the broccoli extract topically twice a day. Wound tissues on each group are observed microscopically on 3th, 7th, and 14th day. The density of collagen fibers was measured based on the calculation of semiquantitative score. Result: The result showed that wound healing on treatment group tends to be better compared with control group with the increase of collagen score of treatment group. The result of Statistical test Man-Whitney with confidence level 95% (p &lt; 0,05) with observation on 3th, 7th, and 14th day sequentally is p=0.100, p=0,100, p=0,700. Conclusion: Broccoli extract which is applied topically tends to have more benefits regarding the process of wound healing, eventhough there is no significant difference found on statitistical test.

Effectivity of 5% Temulawak Extract (Curcuma xanthorrhiza) on Post-Extraction Fibroblast Cells in Wistar Rats (Rattus norvegicus)

ABSTRACT Introduction: Socket wound would undergo 3 phases of wound-healing process, i.e. inflammation phase, proliferation phase, and re-modelling phase. In proliferation phase, fibroblast cells were important for producing collagen and elastic cells. One of natural ingredients believed to stimulate fibroblasts is Curcuma xanthorriza. The active compounds in curcuma, namely curcumin and flavonoid, had the ability to increase fibroblast migration and accelerate wound healing. This study aims to observe the effectivity of 5% temulawak extract (Curcuma xanthorrhiza) on post-extraction fibroblast cells in Wistar rats (Rattus norvegicus). Methods: The experiment was conducted on 30 rats that were divided into 2 groups, control group and experimental group. Each group of rats were given intermuscular anesthesia and underwent mandibular incisors extraction. The experiment group was given intermuscular injection of 5% curcuma extract into their wound socket, while control group were given placebo gel injection. On day 3, 5, and 7 decapitation was performed to get the mandibular samples. Furthermore, the number of fibroblast cells was observed using a light microscope with 3 different fields of view at 400 times. Results: The results showed that the mean number of fibroblasts in the experiment group was higher than the control group. Conclusion: 5% temulawak extract (Curcuma xanthorrhiza) had significant effect on increasing post-extraction fibroblast cells in Wistar rats (Rattus norvegicus).