Chronic Cutaneous Wounds Research Articles

Modulating inflammation in a cutaneous chronic wound model by IL-10 released from collagen-silica nanocomposites via gene delivery.

Cutaneous chronic wounds remain a major clinical challenge which requires the development of novel wound dressings. Previously, we showed that collagen-silica nanocomposites consisting of polyethyleneimine (PEI)-DNA complexes associated with silica nanoparticles (SiNP), collagen hydrogel and 3T3 fibroblasts, can work as a local "cell factory". Indeed, the "in-gel" transfection leads to a sustained production and release of biomolecules. Herein, we further explored the possibility for nanocomposites to deliver interleukin-10 (IL-10), a potent anti-inflammatory cytokine, which favors tissue repair. Its anti-inflammatory effect was evaluated in an in vitro inflammation model carried out by LPS (lipopolysaccharide) activation of macrophages embedded in collagen gel. The IL-10 synthesis from nanocomposites was detected over one week in the range of 200-400 pg mL-1 and reached a maximum at day 5 without any observed cytotoxic effects. PEI10-SiNP outperformed free PEI10 and PEI25-SiNP, implying that the introduction of SiNP improved the transfection efficiency of low Mw of PEI. In addition, the structure and mechanical properties of collagen-silica nanocomposites were stable over one week. Subsequently, the ability of nanocomposites to modulate inflammation was tested in a 3D model of inflammation. The decrease of TNF-α and IL-1β gene expression by 20-80% indicated successful inhibition of inflammation by IL-10 released from nanocomposites. Taken together, the nanocomposites are capable of producing effective doses of IL-10 which inhibit the synthesis of pro-inflammatory cytokines and favor the expression of wound healing cytokines. Therefore, the as-constructed 3D gene delivery system represents a promising strategy for the controlled release of therapeutic biomolecules favoring cutaneous wound healing.

Functionalized PVA-silk blended nanofibrous mats promote diabetic wound healing via regulation of extracellular matrix and tissue remodelling.

Chronic cutaneous ulcers, a complex pathophysiological diabetic condition, represent a critical clinical challenge in the current diabetes mellitus pandemic. Consequently, there is a compelling need for bioactive dressings that can trigger healing processes for complete wound repair. Silk fibroin (SF), a natural protein polymer from mulberry and non-mulberry silkworms, has properties that support accelerated wound healing rate. SF from non-mulberry variety possesses additional cell-binding motifs (arginine, glycine, and aspartate), offering cell-material interactions. This study is aimed to investigate wound healing efficacy of dressings made up of various SF varieties blended with poly(vinyl alcohol) biopolymer in alloxan-induced diabetic rabbit model. The nanofibrous mats have been developed using electrospinning and functionalized with growth factors and LL-37 antimicrobial peptide for sustained delivery. Following post 14-day treatment, non-mulberry SF (NMSF)-based dressings healed the wounds faster, in comparison with their mulberry Bombyx mori SF, poly(vinyl alcohol), and control counterparts (p<.01). NMSF-based dressings also supported faster granulation tissue development, angiogenesis, and reepithelialization of wounds. Gene expression study of matrix metalloproteinases and collagen proteins affirmed higher extent of tissue remodelling during the repair process. Furthermore, there was organized extracellular matrix deposition (collagen type I, collagen type III, elastin, and reticulin) and higher wound breaking strength in NMSF compared with other groups after 4weeks. These results validated the potential of NMSF-based bioactive dressings to regulate extracellular matrix deposition leading to faster and complete repair of chronic diabetic cutaneous wounds.

PKCζ as a promising therapeutic target for TNFα-induced inflammatory disorders in chronic cutaneous wounds.

Protein kinase Cζ (PKCζ) is a member of the atypical protein kinase C family. Its roles in macrophages or skin-resident keratinocytes have not been fully evaluated. In this study, we provide evidence that PKCζ mediates lipopolysaccharide (LPS)-induced tumor necrosis factor α (TNFα) gene expression in the mouse macrophage cell line, RAW264.7. TNFα has been proven to be one of the main culprits of chronic wounds and impaired acute wounds, which are characterized by excessive inflammation, enhanced proteolysis and reduced matrix deposition. Among the multiple effects of TNFα on keratinocytes, the induction of chemokines which are indispensable factors involved in the massive infiltration of various inflammatory cells into skin lesions serves as a crucial mechanism. In the present study, we found that PKCζ inhibitor or its specific siRNA inhibited the TNFα-induced upregulation in the levels of the chemokines, interleukin (IL)-8, monocyte chemotactic protein-1 (MCP-1) and intercellular cell adhesion molecule-1 (ICAM-1) in HaCaT keratinocytes. Moreover, under a disrupted inflammatory environment, activated keratinocytes can synthesize large amounts of matrix metalloproteinases (MMP), which has a negative effect on tissue remodeling. We discovered that TNFα promoted the expression of MMP9 in a PKCζ-dependent manner. Further experiments revealed that nuclear factor-κB (NF-κB) was a key downstream molecule of PKCζ. In addition, as shown in vitro, PKCζ was not involved in the TNFα-induced decrease in HaCaT cell migration and proliferation. In vivo experiments demonstrated that TNFα-induced wound closure impairment and inflammatory disorders were significantly attenuated in the PKCζ inhibitor group. On the whole, our findings suggest that PKCζ is a crucial regulator in LPS- or TNFα-induced inflammatory responses in RAW264.7 cells and HaCaT keratinocytes, and that PKCζ/NF-κB signaling may be a potential target for interventional therapy for TNFα-induced skin inflammatory injury.

Volatile organic compound detection as a potential means of diagnosing cutaneous wound infections.

Chronic cutaneous wound infections and surgical site infections (SSIs) present a huge burden on the healthcare system and can lead to increased morbidity and mortality. Current diagnostic methods of identifying and confirming infection involve culture-based and molecular methods. Both techniques are time-consuming and delays commonly lead to untargeted empirical treatment. An ideal diagnostic method would be noninvasive and highly sensitive and detect pathogenic organisms with a high degree of accuracy to allow targeted treatment. Volatile organic compounds (VOCs) are a diverse group of carbon-based molecules produced and released by humans and microorganisms. VOC detection has the potential in aiding cutaneous wound infection diagnostics using noninvasive and time-efficient methods. This review provides a comprehensive update on VOCs produced and emitted by bacteria commonly associated with chronic wounds and SSIs. VOC sampling has the advantage of being painless, time-efficient, noninvasive, and reproducible. VOCs emitted by these organisms are diverse. In vitro studies have identified potential signature volatile profiles, which can be used in detecting these microorganisms. Combining these profiles with volatile profiles emitted from acute, chronic and surgical wounds in vivo could potentially allow identification of bacterial-specific VOCs. VOC detection has the potential for a relatively inexpensive, portable, noninvasive, and reliable clinical diagnostic tool, which could be used in detecting cutaneous wound infections and guiding their optimal management.

Chronic Low-Dose Cadmium Exposure Impairs Cutaneous Wound Healing With Defective Early Inflammatory Responses After Skin Injury.

Impairment of the immune system is a developing concern in evaluating the toxicity of cadmium (Cd). In the present study, we investigated if Cd could impair cutaneous wound healing through interfering with inflammation after injury. We found that exposure of mice to CdCl2 through drinking water at doses of 10, 30, and 50 mg/l for 8 weeks significantly impaired cutaneous wound healing. Chronic 30 mg/l CdCl2 treatment elevated murine blood Cd level comparable to that of low dose Cd-exposed humans, had no effect on blood total and differential leukocyte counts, but reduced neutrophil infiltration, chemokines (CXCL1 and CXCL2), and proinflammatory cytokines (TNFα, IL-1β, and IL-6) expression in wounded tissue at early stage after injury. Wounded tissue homogenates from CdCl2-treated mice had lower chemotactic activity for neutrophils than those from untreated mice. Mechanistic studies showed that chronic Cd treatment suppressed ERK1/2 and NF-κB p65 phosphorylation in wounded tissue at early stage after injury. Compared with neutrophils isolated from untreated mice, neutrophils from CdCl2 treated mice and normal neutrophils treated with CdCl2 invitro both had lower chemotactic response, calcium mobilization and ERK1/2 phosphorylation upon chemoattractant stimulation. Collectively, our study indicate that chronic low-dose Cd exposure impaired cutaneous wound healing by reducing neutrophil infiltration through inhibiting chemokine expression and neutrophil chemotactic response, and suppressing proinflammatory cytokine expression. Cd may suppress chemokine and proinflammatory expression through inactivating ERK1/2 and NF-κB, and inhibit neutrophil chemotaxis by attenuating calcium mobilization and ERK1/2 phosphorylation in response to chemoattractants.

Dicer expression is impaired in diabetic cutaneous wound healing

Diabetes, as a fast growing non-communicable disease, is one of the major health problems of the twenty-first century. Several complications such as cardiovascular disease and renal failure are accompanying diabetes. The chronic cutaneous wound is another diabetes complication, results from the reduced body healing potential. At genome level, diabetic wound environment displays disorganized gene functions emphasizing the critical role of gene regulatory networks in the control of chronic wound repair. MicroRNAs, major regulators of gene activity, have been shown to be impaired in several pathological conditions such as chronic wounds. A reason behind that can be sought in the impaired activity of enzymes involved in the development and production of miRNAs. In current study, streptozocin-induced diabetic rats and non-diabetic controls were used to study the effect of diabetes on Dicer presence in wound environment. Unwounded skin of diabetic animals showed significantly lower level of Dicer expression compared with non-diabetic animal-derived skin. However, at day 7 post-wounding, diabetic animal-derived wounds contained a higher level of Dicer expression compared with non-diabetic ones. Parallel to these findings, the granulation tissue formation and wound closure are impaired in diabetic wounds. This study highlights the dysregulated presence of Dicer at different stages of the diabetic cutaneous wound.

Nanotechnology-Driven Therapeutic Interventions in Wound Healing: Potential Uses and Applications.

The chronic nature and associated complications of nonhealing wounds have led to the emergence of nanotechnology-based therapies that aim at facilitating the healing process and ultimately repairing the injured tissue. A number of engineered nanotechnologies have been proposed demonstrating unique properties and multiple functions that address specific problems associated with wound repair mechanisms. In this outlook, we highlight the most recently developed nanotechnology-based therapeutic agents and assess the viability and efficacy of each treatment, with emphasis on chronic cutaneous wounds. Herein we explore the unmet needs and future directions of current technologies, while discussing promising strategies that can advance the wound-healing field.

Chronic Diseases as Barriers to Oxygen Delivery: A Unifying Hypothesis of Tissue Reoxygenation Therapy.

Modern medical practice has resulted in the accumulation of a growing number of incurable chronic diseases, many of which are inflammatory in nature. Inflammation establishes a hypoxic microenvironment within tissues, a condition of inflammatory hypoxia (IH). Tissues thus affected become severely compromised, are unable to elicit adaptive responses and eventually develop fibrosis and fixed microvascular deficits. Previous work has demonstrated that tissue hypoxia exits even within the simple human model of self-resolving inflammation, the tuberculin reaction. Failed resolution of IH establishes a vicious cycle within tissues that perpetuates tissue hypoxia and resists standard drug therapies. Diseases such as sepsis, chronic cutaneous wounds, kidney disease, traumatic brain injury, solid tumors, inflammatory bowel disease, and chronic bacterial infections (urinary tract infection, cystic fibrosis) are tissue specific manifestations of chronic IH. Successful reversal of IH, through tissue re-oxygenation therapy (TROT), will break this vicious cycle and restore tissue homeostasis. The examples of solid tumors and inflammatory bowel disease are presented to illustrate a theoretical framework to support this hypothesis. Re-oxygenation of compromised tissues must occur before successful treatment of these diverse chronic disease s can be expected.

Exosomes derived from platelet-rich plasma promote the re-epithelization of chronic cutaneous wounds via activation of YAP in a diabetic rat model.

Chronic wounds have become an economic, social, and public health burden and need advanced treatment. Platelet-rich plasma (PRP) has been used extensively in treatment of chronic wounds because it contains an abundance of growth factors secreted by platelets. The exosomes derived from PRP (PRP-Exos) have been proven to encapsulate principal growth factors from platelets. This study is the first to show that these exosomes may exert the function of PRP. PRP-Exos can effectively induce proliferation and migration of endothelial cells and fibroblasts to improve angiogenesis and re-epithelialization in chronic wounds. We regulated YAP to verify the PRP-Exos-dependent effect on fibroblast proliferation and migration through YAP activation. In vivo, we observed the cutaneous healing process in chronic wounds treated with PRP-Exos in a diabetic rat model. We provide evidence of the probable molecular mechanisms underlying the PRP effect on healing of chronic ulcers and describe a promising resource of growth factors from exosomes without species restriction.

Antibacterial activity of copper salts against microorganisms isolated from chronic infected wounds

The antimicrobial activity of copper (Cu+2) is recognized and used as an antimicrobial agent. To evaluate the antimicrobial activity of copper against microorganisms obtained from chronic cutaneous wound infections. Five chemical products that contained copper particles in their composition were tested (zeolite, silica, acetate, nitrate and nanoparticle of copper). The antimicrobial activity against antibiotic resistant strains usually isolated from chronic cutaneous wound infections was determined for two of the products with better performance in copper release. The minimal inhibitory and minimal bactericidal concentrations of copper acetate and nitrate were similar, fluctuating between 400-2,000 µg/ml. The studied copper salts show great potential to be used to control both gram positive and gram negative, antibiotic resistant bacteria isolated from wound infections.

Photobiomodulation with Pulsed and Continuous Wave Near-Infrared Laser (810 nm, Al-Ga-As) Augments Dermal Wound Healing in Immunosuppressed Rats.

Chronic non-healing cutaneous wounds are often vulnerable in one or more repair phases that prevent normal healing and pose challenges to the use of conventional wound care modalities. In immunosuppressed subject, the sequential stages of healing get hampered, which may be the consequences of dysregulated or stagnant wound inflammation. Photobiomodulation (PBM) or low-level laser (light) therapy (LLLT) emerges as a promising drug-free, non-invasive biophysical approach for promoting wound healing, reduction of inflammation, pain and restoration of functions. The present study was therefore undertaken to evaluate the photobiomodulatory effects of 810 nm diode laser (40 mW/cm2; 22.6 J/cm2) with pulsed (10 and 100 Hz, 50% duty cycle) and continuous wave on full-thickness excision-type dermal wound healing in hydrocortisone-induced immunosuppressed rats. Results clearly delineated that 810 nm PBM at 10 Hz was more effective over continuous and 100 Hz frequency in accelerating wound healing by attenuating the pro-inflammatory markers (NF-kB, TNF-α), augmenting wound contraction (α-SM actin), enhancing cellular proliferation, ECM deposition, neovascularization (HIF-1α, VEGF), re-epithelialization along with up-regulated protein expression of FGFR-1, Fibronectin, HSP-90 and TGF-β2 as compared to the non-irradiated controls. Additionally, 810 nm laser irradiation significantly increased CCO activity and cellular ATP contents. Overall, the findings from this study might broaden the current biological mechanism that could be responsible for photobiomodulatory effect mediated through pulsed NIR 810 nm laser (10 Hz) for promoting dermal wound healing in immunosuppressed subjects.

Exploring nurses' and patients' feelings of disgust associated with malodorous wounds: a rapid review.

To identify primary empirical research related specifically to feelings of disgust associated with malodorous chronic cutaneous wounds. A rapid review of the literature using the key words disgust; wounds; malodour and psychosocial. A total of 163 papers were retrieved with seven being included for the final review. Themes emanating from the review were malodour, health-care professionals coping with malodour and disgust. Malodour is a concern to patients, which can sometimes go unreported by nursing staff; although the reasons for this remain unclear. The coping mechanisms developed by nurses in response to 'disgusting' wounds requires further exploration in order for a fuller understanding of these mechanisms to be achieved. This review has identified that both health-care professionals and patients can become distressed at wound odours, yet there is little evidence that is available to guide people as to how to manage these feelings. Hard-to-heal or chronic cutaneous wounds, such as leg ulcers and diabetic foot ulcers, are an increasing global health-care issue. While some research has been undertaken to explore the psychological impact of living with a fungating carcinoma; much less has been written about the management and mitigation of feelings of disgust for patients and families living with a malodorous wound or how health-care professionals can effectively provide psychosocial care.

Stromal cell-derived factor-1 promotes human adipose tissue-derived stem cell survival and chronic wound healing.

Adipose tissue-derived stem cells (ADSCs) hold great potential for the stem cell-based therapy of cutaneous wound healing. Stromal cell-derived factor-1 (SDF-1) activates CXC chemokine receptor (CXCR)4+ and CXCR7+ cells and plays an important role in wound healing. Increasing evidence suggests a critical role for SDF-1 in cell apoptosis and the survival of mesenchymal stem cells. However, the function of SDF-1 in the apoptosis and wound healing ability of ADSCs is not well understood. The aim of this study was to analyze the effect of SDF-1 on the apoptosis and therapeutic effect of ADSCs in cutaneous chronic wounds in vitro and in vivos. By flow cytometric analysis, it was found that hypoxia and serum free promoted the apoptosis of ADSCs. When pretreated with SDF-1, the apoptosis of ADSCs induced by hypoxia and serum depletion was partly recovered. Furthermore, in vivo experiments established that the post-implantation cell survival and chronic wound healing ability of ADSCs were increased following pretreatment with SDF-1 in a diabetic mouse model of chronic wound healing. To explore the potential mechanism underlying the effect of SDF-1 on ADSC apoptosis, western blot analysis was employed and the results indicate that SDF-1 may protect against cell apoptosis in hypoxic and serum-free conditions through activation of the caspase signaling pathway in ADSCs. This study provides evidence that SDF-1 pretreatment can increase the therapeutic effect of ADSCs in cutaneous chronic wounds in vitro and in vivo.

Elevated levels of matrix metalloproteinases and chronic wound healing: an updated review of clinical evidence.

In the past 20 years, research and clinical trials on the healing process of chronic wounds have highlighted the key role of the family of enzymes called matrix metalloproteinases (MMPs). If a strong correlation between the course of healing of chronic wounds and the levels of a biological marker can be demonstrated, then it may be possible to: i) identify the best marker threshold to predict the clinical evolution of the pathology; and ii) if causality has been found between the marker and pathology, to improve the healing outcome, to change the marker level. The databases Medline and Embase were searched to identify clinical trials pertaining to the assessment of MMPs in chronic wounds with the following keywords 'metalloproteinase' or 'metalloprotease' and 'wound healing'. Clinical trials were considered for inclusion if they enrolled patients with cutaneous chronic wounds and were published in English. More than 50 clinical trials, consensus documents and guidelines were assessed for this review. MMPs play key roles in the wound healing process, and excessive expression and activation of some of these enzymes is seen in chronic cutaneous wounds where healing is delayed. Levels of MMPs are affected by a number of factors, including patient and wound characteristics. Levels of MMPs can be used to indicate the prognosis of chronic wounds and protease modulating treatments used to improve healing rates. The authors report no conflicts of interest in this work.

Wound healing potential of medicinal plants with their screening models: A comprehensive review

A wound is a breakage in tissue continuity that can be produced by physical, chemical and thermal damage. It is a generally called as physical injury that cause opening and breaking of skin. Healing of chronic cutaneous wound is a big problem and it involves the restoration of continuity after wounding. Wounds are treated with various medicinal herbs or their extracts. Plants provide various remedies to mankind and herbal plants are nature’s gift used to treat wound with much lesser side effects. Some of those plants are Acalypha langiana, Tinospora cardifolia, Tragia involucrata, Napoleona Imperialis, Prosopis cineria, Lawsonia alba,Ginkgo biloba, Aloe vera, Catharanthus roseus. This review discusses about the wound healing potential of herbal plants and provides overview on wound healing problems and solution. A wound is a breakage in tissue continuity that can be produced by physical, chemical and thermal damage. It is a generally called as physical injury that cause opening and breaking of skin. Healing of chronic cutaneous wound is a big problem and it involves the restoration of continuity after wounding. Wounds are treated with various medicinal herbs or their extracts. Plants provide various remedies to mankind and herbal plants are nature’s gift used to treat wound with much lesser side effects. Some of those plants are Acalypha langiana, Tinospora cardifolia, Tragia involucrata, Napoleona Imperialis, Prosopis cineria, Lawsonia alba,Ginkgo biloba, Aloe vera, Catharanthus roseus. This review discusses about the wound healing potential of herbal plants and provides overview on wound healing problems and solution. Key words: wound healing, herbal remedies, open wound, close wound, models.

Silica-collagen nanocomposites for local and sustained release of Interleukin 10 (IL-10) to treat cutaneous chronic wounds

Event Abstract Back to Event Silica-collagen nanocomposites for local and sustained release of Interleukin 10 (IL-10) to treat cutaneous chronic wounds Xiaolin Wang1, Thibaud Coradin1 and Christophe Helary1 1 Sorbonne Universités, UPMC Univ Paris 06, CNRS, Collège de France, UMR 7574, Chimie de la Matière Condensée, France Cutaneous chronic wounds are characterized by the absence of healing six weeks after the injury. The classic treatment is the debridement of the wound bed followed by a compression method. When this technique is not effective enough, the application of wound dressings is required. Several hulman trials with protein therapy have failed because of the rapid diffusion and short half-life of the cytokines in the wound[1]. Therefore gene therapy represents an interesting alternative. Local delivery of nucleic acids through a hydrogel extends the application of gene therapy for the treatment of chronic wounds. However, the inactivation and fast release of encapsulated DNA strongly compromise their efficacy. Nanoscale delivery systems such as silica nanoparticles (SiNPs) hold great promise for gene therapy owing to their high cellular uptake, DNA protection and possible cell targeting[2]. In this study, nanocomposites consisting of plasmid DNA-PEI-SiNP complexes, collagen hydrogel and 3T3 mouse fibroblasts have been evaluated as gene delivery systems to obtain a local and sustained release of biomolecules. Plasmid DNA encoding for Interleukin 10 (IL-10) was chosen as this cytokine is able to modulate inflammation of chronic wounds. SiNPs were modified with PEI (polyethyleneimine) of different molecular weights (1.8 kDa, 10 kDa and 25 kDa) by electrostatic absorption. SiNP-PEI complexes were associated with plasmids encoding for Luciferase or human IL-10 at a weight ratio of 30:1. Then, complexes were encapsulated within collagen hydrogel with 3T3 mouse fibroblasts. Cell transfection was assessed by measuring the luciferase activity or the IL-10 production. Cell viability was evaluated by Alamar Blue Assay. Subsequently, the effect of nanocomposites to modulate inflammation was evaluated on activated mouse RAW 264.7 macrophages. The ability of IL-10 doses released from nanocomposites to downregulate the TNF-α expression in macrophages was analyzed over one week. Successful cell transfection within the collagen/silica nanocomposites was detected by sustained release of luciferase over one week. The best transfection efficiency was obtained with PEI 10KDa (Figure 1). When compared with the soluble form of PEI 25 KDa, the transfection was lower. However, the incubation with increasing quantities of soluble PEI or complexed with SINP revealed a cytotoxicity of PEI 25 KDa and 10 KDa from 10 µg/mL (Figure 1). In contrast, PEI was not toxic until the 100 µg/mL when associated with silica nanoparticles. Interestingly, SiNP-PEI complexes were confined within the collagen network as no transfection was possible out of the nanocomposites. Finally, SiNP-PEI complexes were confined within the collagen network as no transfection was possible out of the nanocomposites. Tested on activated macrophages, nanocomposites permitted the sustained release of IL-10 (500 pg/mL) which could inhibit the expression of TNF-α by 50% in macrophages (Figure 2). These results show that nanocomposites obtained by entrapping SiNP-PEI-DNA together with cells inside a collagen hydrogel can work as a reservoir for local and controlled gene delivery. In addition, it is possible to create cell factories producing high doses of IL-10 which modulate inflammation. These biomaterials are promising for the local treatment of cutaneous chronic wounds. Bernard Haye; Corinne Illoul

Hair follicle units promote re-epithelialization in chronic cutaneous wounds: A clinical case series study.

Chronic cutaneous wounds are one of the most unfavorable pathophysiological processes in routine practice. However, developments in hair follicle unit therapy may aid the treatment of these wounds. The aim of the present study was to investigate the function of hair follicle units in chronic cutaneous wound re-epithelialization and to develop an effective protocol for wound treatment. A total of 14 patients, of which nine were male and five were female, with a mean age of 60.71 years (range, 19-76 years) and a mean wound area of 74.14 cm2, were treated in the study. The hair follicle units were dissected from a scalp graft and transplanted into the chronic cutaneous wound bed, after which clinical evaluation was performed. Images of the recipient site were captured at 0, 1, 2, 3, 4, 5, 8 and 14 weeks following transplantation. In addition, histological examinations were conducted postoperatively at week 16. Total wound re-epithelialization was observed in all the patients. Histological analysis revealed that the epidermis and papillary dermis were present in the wound area. Adnexal structures and the reticular dermis were also observed. Therefore, the present study demonstrated the ability of hair follicle units to promote chronic cutaneous wound healing.

Evaluation of dense collagen matrices as medicated wound dressing for the treatment of cutaneous chronic wounds.

Cutaneous chronic wounds are characterized by an impaired wound healing which may lead to infection and amputation. When current treatments are not effective enough, the application of wound dressings is required. To date, no ideal biomaterial is available. In this study, highly dense collagen matrices have been evaluated as novel medicated wound dressings for the treatment of chronic wounds. For this purpose, the structure, mechanical properties, swelling ability and in vivo stability of matrices concentrated from 5 to 40 mg mL(-1) were tested. The matrix stiffness increased with the collagen concentration and was associated with the fibril density and thickness. Increased collagen concentration also enhanced the material resistance against accelerated digestion by collagenase. After subcutaneous implantation in rats, dense collagen matrices exhibited high stability without any degradation after 15 days. The absence of macrophages and neutrophils evidenced their biocompatibility. Subsequently, dense matrices at 40 mg mL(-1) were evaluated as drug delivery system for ampicillin release. More concentrated matrices exhibited the best swelling abilities and could absorb 20 times their dry weight in water, allowing for an efficient antibiotic loading from their dried form. They released efficient doses of antibiotics that inhibited the bacterial growth of Staphylococcus Aureus over 3 days. In parallel, they show no cytotoxicity towards human fibroblasts. These results show that dense collagen matrices are promising materials to develop medicated wound dressings for the treatment of chronic wounds.

Constitution of fibrin-based niche for in vitro differentiation of adipose-derived mesenchymal stem cells to keratinocytes.

Epithelialization of chronic cutaneous wound is troublesome and may require use of skin/cell substitutes. Adipose-derived mesenchymal stem cells (ADMSCs) have immense potential as autologous cell source for treating wounds; they can cross the germ layer boundary of differentiation and regenerate skin. When multipotent adult stem cells are considered for skin regeneration, lineage committed keratinocytes may be beneficial to prevent undesirable post-transplantation outcome. This study hypothesized that ADMSCs may be directed to epidermal lineage in vitro on a specifically designed biomimetic and biodegradable niche. Cells were seeded on the test niche constituted with fibrin, fibronectin, gelatin, hyaluronic acid, laminin V, platelet growth factor, and epidermal growth factor in the presence of cell-specific differentiation medium (DM). The ADMSCs grown on bare tissue culture polystyrene surface in DM is designated DM-control and those grown in basal medium (BM) is the BM-control. Lineage commitment was monitored with keratinocyte-specific markers such as cytokeratin 14, cytokeratin 5, cytokeratin 19, and integrin α6 at the transcriptional/translational level. The in vitro designed biomimetic fibrin composite matrix may have potential application as cell transplantation vehicle.

Expression and integrity of dermatopontin in chronic cutaneous wounds: a crucial factor in impaired wound healing.

Chronic cutaneous wound (CCW) is a major health care burden wherein the healing process is slow or rather static resulting in anatomical and functional restriction of the damaged tissue. Dysregulated expression and degradation of matrix proteins, growth factors and cytokines contribute to the disrupted and uncoordinated healing process of CCW. Therefore, therapeutic approaches for effective management of CCW should be focused towards identifying and manipulating the molecular defects, such as reduced bioavailability of the pro-healing molecules and elevated activity of proteases. This study essentially deals with assessing the expression and integrity of an extracellular matrix protein, Dermatopontin (DPT), in CCW using real-time quantitative reverse transcriptase PCR and immunological techniques. The results indicate that, despite DPT's high mRNA expression, the protein levels are markedly reduced in both CCW tissue and its exudate. To elucidate the cause for this contradiction in mRNA and protein levels, the stability of DPT is analyzed in the presence of wound exudates and various proteases that are naturally elevated in CCW. DPT was observed to be degraded at higher rates when incubated with certain recombinant proteases or chronic wound exudate. In conclusion, the susceptibility of DPT protein to specific proteases present at high levels in the wound milieu resulted in the degradation of DPT, thus leading to impaired healing response in CCW.