Extracellular Matrix Reorganization During Wound Healing and Its Impact on Abnormal Scarring

Molecular mechanics of Staphylococcus aureus adhesin, CNA, and the inhibition of bacterial adhesion by stretching collagen

Bacterial adhesion to collagen, the most abundant protein in humans, is a critical step in the initiation and persistence of numerous bacterial infections. In this study, we explore the collagen binding mechanism of the multi-modular cell wall anchored collagen adhesin (CNA) in Staphylococcus aureus and examine how applied mechanical forces can modulate adhesion ability. The common structural-functional elements and domain organization of CNA are present across over 50 genera of bacteria. Through the use of molecular dynamics models and normal mode analysis, we shed light on the CNA's structural and conformational dynamics and its interactions with collagen that lead to collagen binding. Our results suggest that the linker region, CNA165-173, acts as a hinge exhibiting bending, extensional, and torsional modes of structural flexibility and its residues are key in the interaction of the CNA-collagen complex. Steered molecular dynamics simulations were conducted with umbrella sampling. During the course of these simulations, the 'locking' latch from the CNA N2 domain was dissociated from its groove in the CNA N1 domain, implying the importance of the latch for effective ligand binding. Finally, we observed that the binding efficiency of the CNA N1-N2 domains to collagen decreases greatly with increasing tensile force application to the collagen peptides. Thus, CNA and similar adhesins might preferentially bind to sites in which collagen fibers are cleaved, such as in wounded, injured, or inflamed tissues, or in which the collagenous tissue is less mature. As alternative techniques for control of bacterial infection are in-demand due to the rise of bacterial antibiotic resistance, results from our computational studies with respect to the mechanoregulation of the collagen binding site may inspire new therapeutics and engineering solutions by mechanically preventing colonization and/or further pathogenesis.

Current and Emerging Treatments for Postsurgical Cleft Lip Scarring: Effectiveness and Mechanisms

Cleft lip with or without cleft palate is the most common congenital malformation of the head and the third-most common birth defect. Surgical repair of the lip is the only treatment and is usually performed during the first year of life. Hypertrophic scar (HTS) formation is a frequent postoperative complication that impairs soft tissue form, function, or movement. Multiple lip revision operations are often required throughout childhood, attempting to optimize aesthetics and function. The mechanisms guiding HTS formation are multifactorial and complex. HTS is the result of dysregulated wound healing, where excessive collagen and extracellular matrix proteins are deposited within the wound area, resulting in persistent inflammation and resultant fibrosis. Many studies support the contribution of dysregulated, exaggerated inflammation in scar formation. Fibrosis and scarring result from chronic inflammation that interrupts tissue remodeling in normal wound healing. Failure of active resolution of inflammation pathways has been implicated. The management of HTS has been challenging for clinicians, since current therapies are minimally effective. Emerging evidence that specialized proresolving mediators of inflammation accelerate wound healing by preventing chronic inflammation and allowing natural uninterrupted tissue remodeling suggests new therapeutic opportunities in the prevention and management of HTS.

Homeobox B9 facilitates hypertrophic scar formation via activating the mitogen-activated protein kinase signaling pathway

The functions and underlying mechanisms of homeobox B9 (HOXB9) in scar formation remain unclear; therefore, the present study aimed to investigate whether HOXB9 is highly expressed in hypertrophic scar formation. Immunohistochemistry was performed to examine the expression levels of laminin, fibronectin (FN), collagen type I (Col1) and HOXB9 in hypertrophic scar and healthy skin tissues, and in lentivirus‑constructed HOXB9‑overexpressed or ‑silenced fibroblasts (FBs). Reverse transcription‑quantitative polymerase chain reaction and western blotting were performed to evaluate the mRNA and protein expression levels of HOXB9, laminin, FN, Col1, extracellular signal‑regulated kinase (ERK), c‑Jun N‑terminal kinase (JNK), p38, p‑c‑Jun N‑terminal kinase (JNK), p‑ERK and p‑p38. A gel contraction assay was used to evaluate the effect of HOXB9 on FB contraction. Co‑immunoprecipitation assays were performed to verify the reciprocal interactions between HOXB9 and ERK, JNK and p38. It was demonstrated that HOXB9, laminin, FN and Col1 were upregulated in hypertrophic scar tissues, and HOXB9 upregulated laminin, FN, Col1, p‑ERK, p‑JNK and p38, potentially by interacting directly with p38. Furthermore, FBs overexpressing HOXB9 exhibited enhanced contractile capacity. In conclusion, the present study demonstrated that HOXB9 may facilitate hypertrophic scar formation via activating the mitogen‑activated protein kinase signaling pathway.

Current Therapeutic Approach to Hypertrophic Scars

Abnormal scarring and its accompanying esthetic, functional, and psychological sequelae still pose significant challe nges. To date, there is no satisfactory prevention or treatment option for hypertrophic scars (HSs), which is mostly due to not completely comprehending the mechanisms underlying their formation. That is why the apprehension of regular and controlled physiological processes of scar formation is of utmost importance when facing hypertrophic scarring, its pathophysiology, prevention, and therapeutic approach. When treating HSs and choosing the best treatment and prevention modality, physicians can choose from a plethora of therapeutic options and many commercially available products, among which currently there is no efficient option that can successfully overcome impaired skin healing. This article reviews current therapeutic approach and emerging therapeutic strategies for the management of HSs, which should be individualized, based on an evaluation of the scar itself, patients’ expectations, and practical, evidence-based guidelines. Clinicians are encouraged to combine various prevention and treatment modalities where combination therapy that includes steroid injections, 5-fluorouracil, and pulsed-dye laser seems to be the most effective. On the other hand, the current therapeutic options are usually empirical and their results are unreliable and unpredictable. Therefore, there is an unmet need for an effective, targeted therapy and prevention, which would be based on an action or a modulation of a particular factor with clarified mechanism of action that has a beneficial effect on wound healing. As the extracellular matrix has a crucial role in cellular and extracellular events that lead to pathological scarring, targeting its components mostly by regulating bone morphogenetic proteins may throw up new therapeutic approach for reduction or prevention of HSs with functionally and cosmetically acceptable outcome.

Low-level laser therapy (780 nm) combined with collagen sponge scaffold promotes repair of rat cranial critical-size defects and increases TGF-β, FGF-2, OPG/RANK and osteocalcin expression

The aim of this study was to evaluate the effect of collagen sponge scaffold (CSS) implantation associated with low-level laser therapy (LLLT) on repairing bone defects. A single 5-mm cranial defect was surgically created in forty Wistar rats, which then received one of the following four interventions (n = 10 per group): no treatment (G0); bone defect implanted with collagen sponge scaffold (CSS) alone (G1); defect treated with low-level laser therapy (LLLT) (wavelength 780 nm; total energy density 120 J/cm² ; power 50 mW) alone (G2); and CSS associated with LLLT treatment (G3). After surgery, animals in each group were euthanized at 21 days and 30 days (n = 5 per euthanasia time group). Bone formation was monitored by X-ray imaging analysis. Biopsies were collected and processed for histological analysis and immunohistochemical evaluation of transforming growth factor-beta (TGF-β), fibroblast growth factor-2 (FGF-2), osteoprotegerin (OPG) and receptor activator of nuclear factor ƙ (RANK). Osteocalcin (OCN) was detected by immunofluorescence analysis. Compared to the G0 group, defects in the 30-day G3 group exhibited increased bone formation, both by increase in radiopaque areas (P < 0.01) and by histomorphometric analysis (P < 0.001). The histopathological analysis showed a decreased number of inflammatory cells (P < 0.001). The combined CCS + LLLT (G3) treatment also resulted in the most intense immunostaining for OPG, RANK, FGF-2 and TGF-β, and the most intense and diffuse OCN immunofluorescent labelling at 30 days postsurgery (G3 vs. G0 group, P < 0.05). Therefore, the use of CCS associated with LLLT could offer a synergistic advantage in improving the healing of bone fractures.

Adiponectin Is Involved in Connective Tissue Growth Factor-Induced Proliferation, Migration and Overproduction of the Extracellular Matrix in Keloid Fibroblasts

Adiponectin, an adipocyte-derived hormone, exerts pleiotropic biological effects on metabolism, inflammation, vascular homeostasis, apoptosis and immunity. Recently, adiponectin has been suggested to attenuate the progression of human dermal fibrosis. Connective tissue growth factor (CTGF) is induced in keloids and is thought to be participated in the formation of keloid fibrosis. However, the roles played by adiponectin in keloids remain unclear. In this study, we explored the effects of adiponectin on CTGF-induced cell proliferation, migration and the deposition of extracellular matrix (ECM) and their associated intracellular signalling pathways in keloid fibroblasts (KFs). We also explored possible mechanisms of keloid pathogenesis. Primary fibroblast cultures were established from foreskin biopsies and skin biopsies from patients with keloids. The expression of adiponectin and adiponectin receptors (adipoRs) was evaluated by reverse transcription-PCR (RT-PCR), quantitative real-time RT-PCR, immunofluorescence staining, and immunohistochemical analysis. Next, KFs and normal dermal fibroblasts (NFs) were treated with CTGF in the presence or absence of adiponectin. A cell counting kit-8 (CCK-8) and the Transwell assay were used to examine cell proliferation and migration. The level of the collagen I, fibronectin (FN) and α-smooth muscle actin (α-SMA) mRNAs and proteins were determined by quantitative real-time RT-PCR and western blotting. The effects of RNA interference (RNAi) targeting the adipoR genes were detected. Phosphorylation of adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK), mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3 kinase-protein kinase (PI3K-Akt) were examined by western blotting to further investigate the signalling pathways. Furthermore, inhibitors of signal transduction pathways were investigated. The expression levels of adiponectin and adipoRs were significantly decreased in keloids compared with those in normal skin tissue. Adiponectin suppressed the CTGF-induced KFs, but not NFs, proliferation, migration and ECM production. Moreover, adiponectin inhibited the phosphorylation of AMPK, p38 and extracellular-regulated kinase (ERK), but not that of Jun N-terminal kinase (JNK) or Akt, in CTGF-treated KFs. The activity of adiponectin-mediated signalling pathways was attenuated by small interfering RNAs (siRNAs) targeting adipoR1 (but not siRNAs targeting adipoR2, T-cadherin or calreticulin), AMPK (Compound C), p38 (SB203580) inhibitors, and mitogen-activated protein kinase kinase (MEK) inhibitor (PD98059). Based on our results, adiponectin suppresses CTGF-induced KFs proliferation, migration and ECM overproduction. One of the underlying mechanisms is the activation of the adipoR1, AMPK, p38, and ERK signalling pathways. Therefore, adiponectin may play an important role in the progression of keloids, suggesting a potential novel target for keloid treatment.

Natural healing-inspired collagen-targeting surgical protein glue for accelerated scarless skin regeneration

Skin scarring after deep dermal injuries is a major clinical problem due to the current therapies limited to established scars with poor understanding of healing mechanisms. From investigation of aberrations within the extracellular matrix involved in pathophysiologic scarring, it was revealed that one of the main factors responsible for impaired healing is abnormal collagen reorganization. Here, inspired by the fundamental roles of decorin, a collagen-targeting proteoglycan, in collagen remodeling, we created a scar-preventive collagen-targeting glue consisting of a newly designed collagen-binding mussel adhesive protein and a specific glycosaminoglycan. The collagen-targeting glue specifically bound to type I collagen in a dose-dependent manner and regulated the rate and the degree of fibrillogenesis. In a rat skin excisional model, the collagen-targeting glue successfully accelerated initial wound regeneration as defined by effective reepithelialization, neovascularization, and rapid collagen synthesis. Moreover, the improved dermal collagen architecture was demonstrated by uniform size of collagen fibrils, their regular packing, and a restoration of healthy tissue component. Collectively, our natural healing-inspired collagen-targeting glue may be a promising therapeutic option for improving the healing rate with high-quality and effective scar inhibition.

A prospective study of the safety and efficacy of a combined bipolar radiofrequency, intense pulsed light, and infrared diode laser treatment for global facial photoaging

The clinical features of photoaging include: skin texture changes, laxity, rhytides, pigmentary changes, and vascular changes such as erythema and telangiectasias. In order to meet patients' increasing demands for improving all aspects of photoaging at one office visit, employing a multi-modality treatment for all aspects of photoaging has become increasingly desirable for the physician and patient alike. We examine a novel device that employs bipolar radiofrequency (RF), intense pulsed light (IPL), and infrared diode laser. These laser and light source treatments are performed sequentially. This study aims to evaluate the clinical efficacy and safety of this device (i.e., ELOS Triniti™). Twenty-six subjects received four ELOS Triniti™ treatments at 1-month intervals. They were followed up 1, 3, and 6 months after completing the treatments. Two blinded dermatologists used a comprehensive grading scale to evaluate the degree of the photoaging in terms of rhytides, laxity, dyschromia, erythema, telangiectasias, and texture. Subjects used a 0-10 grading scale for self-assessment of photoaging. Additionally, we measured the Erythema Index (EI), Melanin Index (MI), transepidermal water loss scores (TEWL), stratum corneum moisture scores (SC), and dermis moisture scores (D) before treatment and 1, 3, and 6 months after treatment. There was a statistically significant improvement in all five aspects of the comprehensive grading scale. Overall, it had excellent efficacy for improving erythema, telangiectasias, and skin texture. It also had a relatively long effect on improving skin laxity; however, it had only a limited ability to improve rhytides and dyschromia. It can mildly to moderately improve the global photoaging. This global effect can be noted 1 month after treatment and becomes most clinically apparent 3 months after treatment. This is maintained at least 6 months after treatment. MI index and SC and D values increased while EI index and TEWL values decreased after the treatment. The subjects' self-assessment improved by 2.7 ± 1.2 points. The overall satisfaction rate was 88%. The degree of pain measured 2.5 ± 1.9 points on average. There was no downtime and no severe side effects reported. The sequential implementation of bipolar radiofrequency based optical combination devices (IPL, IR, diode laser) is effective and safe for global facial photoaging.

Evaluation of subcutaneous infiltration of autologous platelet-rich plasma on skin-wound healing in dogs

Platelet-rich plasma (PRP) is known to be rich in growth factors and cytokines, which are crucial to the healing process. This study investigate the effect of subcutaneous (S/C) infiltration of autologous PRP at the wound boundaries on wound epithelization and contraction. Five adult male mongrel dogs were used. Bilateral acute full thickness skin wounds (3 cm diameter) were created on the thorax symmetrically. Right side wounds were subcutaneously infiltrated with activated PRP at day 0 and then every week for three consecutive weeks. The left wound was left as control. Wound contraction and epithelization were clinically evaluated. Expression of collagen type I (COLI) A2, (COLIA2),histopathology and immunohistochemical (IHC) staining of COLI α1 (COLIA1) were performed on skin biopsies at first, second and third weeks. The catalase activity, malondialdehyde (MDA) concentration and matrix metalloproteinase (MMP) 9 (MMP-9) activity were assessed in wound fluid samples. All data were analysed statistically. The epithelization percent significantly increased in the PRP-treated wound at week 3. Collagen was well organized in the PRP-treated wounds compared with control wounds at week 3. The COLIA2 expression and intensity of COLIA1 significantly increased in PRP-treated wounds. MDA concentration was significantly decreased in PRP-treated wound at week 3. The catalase activity exhibited no difference between PRP treated and untreated wounds. The activity of MMP-9 reached its peak at the second week and was significantly high in the PRP-treated group. S/C infiltration of autologous PRP at the wound margins enhances the wound epithelization and reduces the scar tissue formation.

Regulation of matrix metalloproteinase-2 and -9 during healing of dermal wounds after incision using radiofrequency energy in neonatal and adult rats

BACKGROUND

Radiofrequency energy (RFE) has many medical applications in the treatment of adults and children. The impact of RFE on healing-regulation systems in the developing tissues is not fully known. Matrix metalloproteinases (MMPs) are involved in the remodeling of the extracellular matrix and the inflammatory processes. MMPs are regulated differently among the different age groups. We evaluated possible changes in MMP activity after an incisional wound using a radiofrequency scalpel in neonatal and adult rats.

METHODS

In 30 Wistar rats [15 4-day-old (neonates) and 15 4-month-old (adults) rats], a ventral wound was created using a radiofrequency scalpel. Wounded areas and non-wounded tissues were harvested one, three and seven days after the intervention. Enzymatic activities of MMP-2 and MMP-9 were evaluated using gelatin zymography.

RESULTS

Adults expressed higher activity than neonates for MMP-2 on day 7 (Mann -Whitney U-test, p =0.009) and for MMP-9 on days one (p =0.005) and three (p =0.005). MMP-9 was expressed in higher amounts in the wounded tissue in comparison with non-wounded tissue during days one and three (Wilcoxon signed rank test, p =0.028 and p =0.043, respectively). MMP-2 was produced in equal amounts in the wounded and non-wounded tissue at all time-points. Only in the adult wounds at day seven, higher activity was noted compared with non-wounded skin (Wilcoxon signed rank test, p=0.043).

CONCLUSIONS

RFE, despite its local burning effect, does not interfere with known patterns of MMP regulation. Neonates have lower activity of MMPs than adults. Energy conduction through adjacent non-wounded tissues does not have an impact upon MMP regulation. HIPPOKRATIA 2017, 21(1): 85-92.

An overview of the therapeutic potential of regenerative medicine in cutaneous wound healing

The global burden of disease associated with wounds is an increasingly significant public health concern. Current treatments are often expensive, time-consuming and limited in their efficacy in chronic wounds. The challenge of overcoming current barriers associated with wound care requires innovative management techniques. Regenerative medicine is an emerging field of research that focuses on the repair, replacement or regeneration of cells, tissues or organs to restore impaired function. This article provides an overview of the pathophysiology of wound healing and reviews the latest evidence on the application of the principal components of regenerative medicine (growth factors, stem cell transplantation, biomaterials and tissue engineering) as therapeutic targets. Improved knowledge and understanding of the pathophysiology of wound healing has pointed to new therapeutic targets. Regenerative medicine has the potential to underpin the design of specific target therapies in acute and chronic wound healing. This personalised approach could eventually reduce the burden of disease associated with wound healing. Further evidence is required in the form of large animal studies and clinical trials to assess long-term efficacy and safety of these new treatments.

Non-Coding RNAs: New Players in Skin Wound Healing

Significance: Wound healing is a basic physiological process that is utilized to keep the integrity of the skin. Impaired wound repair, such as chronic wounds and pathological scars, presents a major health and economic burden worldwide. To date, efficient targeted treatment for these wound disorders is still lacking, which is largely due to our limited understanding of the biological mechanisms underlying these diseases. Research driven around discovering new therapies for these complications is, therefore, an urgent need. Recent Advances: The vast majority of the human genome is transcribed to RNAs that lack protein-coding capacity. Intensive research in the recent decade has revealed that these non-coding RNAs (ncRNAs) function as important regulators of cellular physiology and pathology, which makes them promising therapeutic and diagnostic entities. Critical Issues: A class of short ncRNAs, microRNAs, has been found to be indispensable for all the phases of skin wound healing and plays important roles in the pathogenesis of wound complications. The role of long ncRNAs (lncRNA) in skin wound healing remains largely unexplored. Recent studies revealed the essential role of lncRNAs in epidermal differentiation and stress response, indicating their potential importance for skin wound healing, which warrants future research. Future Directions: An investigation of ncRNAs will add new layers of complexity to our understanding of normal skin wound healing as well as to the pathogenesis of wound disorders. Development of ncRNA-based biomarkers and treatments is an interesting and important avenue for future research on wound healing.

Topological Control of Extracellular Matrix Growth: A Native-Like Model for Cell Morphodynamics Studies

The interaction of cells with their natural environment influences a large variety of cellular phenomena, including cell adhesion, proliferation, and migration. The complex extracellular matrix network has challenged the attempts to replicate in vitro the heterogeneity of the cell environment and has threatened, in general, the relevance of in vitro studies. In this work, we describe a new and extremely versatile approach to generate native-like extracellular matrices with controlled morphologies for the in vitro study of cellular processes. This general approach combines the confluent culture of fibroblasts with microfabricated guiding templates to direct the three-dimensional growth of well-defined extracellular networks which recapitulate the structural and biomolecular complexity of features typically found in vivo. To evaluate its performance, we studied fundamental cellular processes, including cell cytoskeleton organization, cell-matrix adhesion, proliferation, and protrusions morphodynamics. In all cases, we found striking differences depending on matrix architecture and, in particular, when compared to standard two-dimensional environments. We also assessed whether the engineered matrix networks influenced cell migration dynamics and locomotion strategy, finding enhanced migration efficiency for cells seeded on aligned matrices. Altogether, our methodology paves the way to the development of high-performance models of the extracellular matrix for potential applications in tissue engineering, diagnosis, or stem-cell biology.

Phospholipase Cε deficiency delays the early stage of cutaneous wound healing and attenuates scar formation in mice

This study aimed to investigate the role of phospholipase Cε (PLCε) in the skin wound healing process. PLCε, an effect factor of Ras/Rap small G protein, plays a crucial role in skin inflammation by regulating inflammatory cytokines. Inflammatory responses are closely associated with wound healing. Full-thickness skin wounds were made in the PLCε knockout (KO) and wild-type (WT) mice, and the healing process was analyzed. The macroscopic wound closure rate declined in the PLCε KO mice on days 3, 4, and 5 after wounding, following the decreased expression of interleukin (IL)-6, chemokine (C-X-C motif) ligand (Cxcl)-1, Cxcl-2, and chemokine (C-C motif) ligand (Ccl) 20. The proliferation rate of epidermal keratinocytes was not affected by PLCε, but silencing of PLCε resulted in the delayed migration of keratinocytes. Moreover, the scars were found to be much smaller in the PLCε KO mice than in the WT mice. The mRNA expression of Ccl20, collagen (Col) 6a1, and Col17a1 decreased in the PLCε KO mice. These results were in agreement with a previous hypothesis that PLCε might delay the early stage of cutaneous wound healing by inhibiting the migration of keratinocytes, and decrease the expression of Col6a1, Col17a1, and Ccl20 by inhibiting the inflammatory response to reduce scar formation. This study shed light on a novel role of PLCε in wound healing and provided new therapeutic approaches to target PLCε for diminishing scar formation after injury.

Manipulating mammalian cell morphologies using chemical-mechanical polished integrated circuit chips

Tungsten chemical-mechanical polished integrated circuits were used to study the alignment and immobilization of mammalian (Vero) cells. These devices consist of blanket silicon oxide thin films embedded with micro- and nano-meter scale tungsten metal line structures on the surface. The final surfaces are extremely flat and smooth across the entire substrate, with a roughness in the order of nanometers. Vero cells were deposited on the surface and allowed to adhere. Microscopy examinations revealed that cells have a strong preference to adhere to tungsten over silicon oxide surfaces with up to 99% of cells adhering to the tungsten portion of the surface. Cells self-aligned and elongated into long threads to maximize contact with isolated tungsten lines as thin as 180 nm. The orientation of the Vero cells showed sensitivity to the tungsten line geometric parameters, such as line width and spacing. Up to 93% of cells on 10 μm wide comb structures were aligned within ± 20° of the metal line axis. In contrast, only ~22% of cells incubated on 0.18 μm comb patterned tungsten lines were oriented within the same angular interval. This phenomenon is explained using a simple model describing cellular geometry as a function of pattern width and spacing, which showed that cells will rearrange their morphology to maximize their contact to the embedded tungsten. Finally, it was discovered that the materials could be reused after cleaning the surfaces, while maintaining cell alignment capability.

MicroRNAs Associated with Shoulder Tendon Matrisome Disorganization in Glenohumeral Arthritis

The extracellular matrix (ECM) provides core support which is essential for the cell and tissue architectural development. The role of ECM in many pathological conditions has been well established and ECM-related abnormalities leading to serious consequences have been identified. Though much has been explored in regards to the role of ECM in soft tissue associated pathologies, very little is known about its role in inflammatory disorders in tendon. In this study, we performed microRNA (miRNA) expression analysis in the long head of the human shoulder biceps tendon to identify key genes whose expression was altered during inflammation in patients with glenohumeral arthritis. We identified differential regulation of matrix metalloproteinases (MMPs) that could be critical in collagen type replacement during tendinopathy. The miRNA profiling showed consistent results between the groups and revealed significant changes in the expression of seven different miRNAs in the inflamed tendons. Interestingly, all of these seven miRNAs were previously reported to have either a direct or indirect role in regulating the ECM organization in other pathological disorders. In addition, these miRNAs were also found to alter the expression levels of MMPs, which are the key matrix degrading enzymes associated with ECM-related abnormalities and pathologies. To our knowledge, this is the first report which identifies specific miRNAs associated with inflammation and the matrix reorganization in the tendons. Furthermore, the findings also support the potential role of these miRNAs in altering the collagen type ratio in the tendons during inflammation which is accompanied with differential expression of MMPs.

Process of Hypertrophic Scar Formation: Expression of Eukaryotic Initiation Factor 6

Background:

Hypertrophic scar is one of the most common complications and often causes the disfigurement or deformity in burn or trauma patients. Therapeutic methods on hypertrophic scar treatment have limitations due to the poor understanding of mechanisms of hypertrophic scar formation. To throw light on the molecular mechanism of hypertrophic scar formation will definitely improve the outcome of the treatment. This study aimed to illustrate the negative role of eukaryotic initiation factor 6 (eIF6) in the process of human hypertrophic scar formation, and provide a possible indicator of hypertrophic scar treatment and a potential target molecule for hypertrophic scar.

Methods:

In the present study, we investigated the protein expression of eIF6 in the human hypertrophic scar of different periods by immunohistochemistry and Western blot analysis.

Results:

In the hypertrophic scar tissue, eIF6 expression was significantly decreased and absent in the basal layer of epidermis in the early period, and increased slowly and began to appear in the basal layer of epidermis by the scar formation time.

Conclusions:

This study confirmed that eIF6 expression was significantly related to the development of hypertrophic scar, and the eIF6 may be a target molecule for hypertrophic scar control or could be an indicator of the outcomes for other treatment modalities.

Inflammation in Chronic Wounds

Non-healing chronic wounds present a major biological, psychological, social, and financial burden on both individual patients and the broader health system. Pathologically extensive inflammation plays a major role in the disruption of the normal healing cascade. The causes of chronic wounds (venous, arterial, pressure, and diabetic ulcers) can be examined through a juxtaposition of normal healing and the rogue inflammatory response created by the common components within chronic wounds (ageing, hypoxia, ischaemia-reperfusion injury, and bacterial colonisation). Wound bed care through debridement, dressings, and antibiotics currently form the basic mode of treatment. Despite recent setbacks, pharmaceutical adjuncts form an interesting area of research.

Overexpression of miR-29b reduces collagen biosynthesis by inhibiting heat shock protein 47 during skin wound healing

Skin scar formation is characterized by excessive synthesis and aberrant deposition of collagens during wound healing. MicroRNAs are endogenous gene regulators critically involved in diverse biological events including skin scar formation and hold considerable promise as therapeutic targets. However, the detailed molecular mechanisms responsible for collagen production during skin wound repair and scar formation remain incompletely known. Here our data revealed that significant downregulation of miR-29b and upregulation of heat shock protein 47 (HSP47) were observed during wound healing in both excisional and burn wound models and also detected in facial skin scar as compared to adjacent healthy skin. HSP47, a specific chaperon for collagen production and secretion, was identified as a novel and direct post-transcriptional target of miR-29b in skin fibroblasts via bioinformatics prediction and experimental validation. Moreover, the regulatory functions of miR-29b in collagen biosynthesis are partially achieved through modulating HSP47 expression in skin fibroblasts. Furthermore, the profibrotic growth factor TGF-β1 inhibited miR-29b transcription by activating TGF-β/Smads signaling and in turn depressed HSP47 and enhanced collagen 1 production. In contrast, the proinflammatory cytokines IL-1β and TNF-α significantly induced miR-29b transcription via activating NF-κB signaling but had no significant effect on HSP47 and collagen production in skin fibroblasts. Importantly, local delivery of miR-29b lentiviral particles inhibited HSP47 expression and collagen biosynthesis as well as suppressed angiogenesis, thus reducing scar formation in an excisional wound splinting model. Collectively, our data reveal that miR-29b can reduce collagen biosynthesis during skin wound healing likely via post-transcriptional inhibition of HSP47 expression. These findings also suggest that therapeutic targeting of miR-29b/HSP47 might be a viable alternative strategy to prevent or reduce scar formation.

A Multicenter Randomized Controlled Trial Evaluating a Cx43-Mimetic Peptide in Cutaneous Scarring

The transmembrane protein Cx43 has key roles in fibrogenic processes including inflammatory signaling and extracellular matrix composition. aCT1 is a Cx43 mimetic peptide that in preclinical studies accelerated wound closure, decreased inflammation and granulation tissue area, and normalized mechanical properties after cutaneous injury. We evaluated the efficacy and safety of aCT1 in the reduction of scar formation in human incisional wounds. In a prospective, multicenter, within-participant controlled trial, patients with bilateral incisional wounds (≥10 mm) after laparoscopic surgery were randomized to receive acute treatment (immediately after wounding and 24 hours later) with an aCT1 gel formulation plus conventional standard of care protocols, involving moisture-retentive occlusive dressing, or standard of care alone. The primary efficacy endpoint was average scarring score using visual analog scales evaluating incision appearance and healing progress over 9 months. There was no significant difference in scar appearance between aCT1- or control-treated incisions after 1 month. At month 9, aCT1-treated incisions showed a 47% improvement in scar scores over controls (Vancouver Scar Scale; P = 0.0045), a significantly higher Global Assessment Scale score (P = 0.0009), and improvements in scar pigmentation, thickness, surface roughness, and mechanical suppleness. Adverse events were similar in both groups. aCT1 has potential to improve scarring outcome after surgery.

Involvement of eIF6 in external mechanical stretch-mediated murine dermal fibroblast function via TGF-β1 pathway

External mechanical loading on a wound commonly increases fibrosis. Transforming growth factor-β1 (TGF-β1) has been implicated in fibrosis in various models, including the mechanical force model. However, the underlying mechanism is unclear. Our previous experiments suggested that eukaryotic initiation factor 6 (eIF6) acted as a regulator of TGF-β1 expression, and negatively impact on collagen synthesis. Our current results showed that external mechanical stretching significantly increased COL1A1, TGF-β1 and eIF6 expression as well as dermal fibroblasts proliferation, both in vitro and in vivo. eIF6 –deficient (eIF6^+/−) cells exhibited significantly higher levels of COL1A1, and these levels increased further with external mechanical stretching, suggesting that mechanical stretching plays a synergistic role in promoting COL1A1 expression in eIF6^+/− cells. Inhibition of TGFβR I/II by LY2109761 decreased COL1A1 protein expression in eIF6^+/− dermal fibroblasts in a cell stretching model, and attenuated granulation tissue formation in partial thickness wounds of eIF6^+/− mice. These data suggest that mechanical stretching has a synergistic role in the expression of COL1A1 in eIF6^+/− cells, and is mediated by activation of TGFβRI/II. Taken together, our results indicate that eIF6 may be involved in external mechanical force-mediated murine dermal fibroblast function at least partly through the TGF-β1 pathway.

Biohybrid cochlear implants in human neurosensory restoration

BACKGROUND

The success of cochlear implantation may be further improved by minimizing implantation trauma. The physical trauma of implantation and subsequent immunological sequelae can affect residual hearing and the viability of the spiral ganglion. An ideal electrode should therefore decrease post-implantation trauma and provide support to the residual spiral ganglion population. Combining a flexible electrode with cells producing and releasing protective factors could present a potential means to achieve this. Mononuclear cells obtained from bone marrow (BM-MNC) consist of mesenchymal and hematopoietic progenitor cells. They possess the innate capacity to induce repair of traumatized tissue and to modulate immunological reactions.

METHODS

Human bone marrow was obtained from the patients that received treatment with biohybrid electrodes. Autologous mononuclear cells were isolated from bone marrow (BM-MNC) by centrifugation using the Regenlab™ THT-centrifugation tubes. Isolated BM-MNC were characterised using flow cytometry. In addition, the release of cytokines was analysed and their biological effect tested on spiral ganglion neurons isolated from neonatal rats. Fibrin adhesive (Tisseal™) was used for the coating of silicone-based cochlear implant electrode arrays for human use in order to generate biohybrid electrodes. Toxicity of the fibrin adhesive and influence on insertion, as well on the cell coating, was investigated. Furthermore, biohybrid electrodes were implanted in three patients.

RESULTS

Human BM-MNC release cytokines, chemokines, and growth factors that exert anti-inflammatory and neuroprotective effects. Using fibrin adhesive as a carrier for BM-MNC, a simple and effective cell coating procedure for cochlear implant electrodes was developed that can be utilised on-site in the operating room for the generation of biohybrid electrodes for intracochlear cell-based drug delivery. A safety study demonstrated the feasibility of autologous progenitor cell transplantation in humans as an adjuvant to cochlear implantation for neurosensory restoration.

CONCLUSION

This is the first report of the use of autologous cell transplantation to the human inner ear. Due to the simplicity of this procedure, we hope to initiate its widespread utilization in various fields.

Growth factor pathways in hypertrophic scars: Molecular pathogenesis and therapeutic implications

Hypertrophic scars represent the most common complication of skin injury and are caused by excessive cutaneous wound healing characterized by hypervascularity and pathological deposition of extracellular matrix (ECM) components. To date, the optimal and specific treatment methods for hypertrophic scars have not been available in the clinic. Current paradigm has established fibroblasts and myofibroblasts as pivotal effector cells in the pathophysiology of wound healing. Their biological properties including origin, proliferation, migration, contraction and ECM regulation have profound impacts on the progression and regression of hypertrophic scars. These complex processes are executed and modulated by a signaling network involving a number of growth factors and cytokines. Of particular importance is transforming growth factor-β, platelet-derived growth factor, connective tissue growth factor, epidermal growth factor, and vascular endothelial growth factor. This review article briefly describes the biological functions of fibroblasts and myofibroblasts during hypertrophic scars, and thereafter examines the up-to-date molecular knowledge on the roles of key growth factor pathways in the pathophysiology of hypertrophic scars. Importantly, the therapeutic implications and future challenges of these molecular discoveries are critically discussed in the hope of advancing therapeutic approaches to limit pathological scar formation.

Short-term effects of vacuum massage on epidermal and dermal thickness and density in burn scars: an experimental study

BACKGROUND

Vacuum massage is a non-invasive mechanical massage technique invented to treat burns and scars. To date, no effects of vacuum massage on thickness and density of human scar tissue have been reported. The process in which external stimuli are converted into biochemical responses in the cell is known as mechanotransduction. In the skin endothelial cells, fibroblasts and myofibroblasts embedded in the extracellular matrix (ECM) sense mechanical stimuli (created by vacuum massage) and may promote intracellular processes leading to matrix remodelling. Since mechanotransduction could be a plausible working mechanism for vacuum massage as an anti-scarring therapy, this study aims to investigate the short-term effects of vacuum massage on thickness and density of epidermis and dermis in burn scars in order to find proof of ECM remodelling.

METHODS

A one group experimental study was performed. Patients with burn scars on upper extremities, lower extremities, and trunk were recruited for participation in this study. The DUB®cutis 22 MHz ultrasound scanner was used to assess thickness and density of the epidermal and dermal skin layers. After baseline measurements, vacuum massage was performed according to a pre-defined protocol. Measurements were carried out at 5 min, 30 min, 1 h, and 2 h post-intervention.

RESULTS

Thirteen scar sites from 9 different patients were investigated. In 8 out of the 13 scar sites, a disruption of the epidermis was noticed after the vacuum massage. Five minutes after the intervention, epidermal density decreased statistically significantly (p = .022) and dermal thickness increased (p = .018). Both changes lasted for more than 1 h, but after 2 h, the changes were no longer statistically significant. Dermal density decreased significantly (p = .048) immediately after the intervention, and this decrease was still present after 2 h (p = .011).

CONCLUSIONS

Preliminary results show that the disruption of the epidermis may indicate that vacuum massage could be able to actually breach the skin barrier. The statistically significant changes in the dermal layers could suggest an increased ECM production after vacuum massage.

Transition from inflammation to proliferation: a critical step during wound healing

The ability to rapidly restore the integrity of a broken skin barrier is critical and is the ultimate goal of therapies for hard-to-heal-ulcers. Unfortunately effective treatments to enhance healing and reduce scarring are still lacking. A deeper understanding of the physiology of normal repair and of the pathology of delayed healing is a prerequisite for the development of more effective therapeutic interventions. Transition from the inflammatory to the proliferative phase is a key step during healing and accumulating evidence associates a compromised transition with wound healing disorders. Thus, targeting factors that impact this phase transition may offer a rationale for therapeutic development. This review summarizes mechanisms regulating the inflammation-proliferation transition at cellular and molecular levels. We propose that identification of such mechanisms will reveal promising targets for development of more effective therapies.