Determination of endogenous growth factors in human wound fluid: temporal presence and profiles of secretion

Tissue adaptation of CD4 T lymphocytes in homeostasis and cancer

The immune system is traditionally classified as a defense system that can discriminate between self and non-self or dangerous and non-dangerous situations, unleashing a tolerogenic reaction or immune response. These activities are mainly coordinated by the interaction between innate and adaptive cells that act together to eliminate harmful stimuli and keep tissue healthy. However, healthy tissue is not always the end point of an immune response. Much evidence has been accumulated over the years, showing that the immune system has complex, diversified, and integrated functions that converge to maintaining tissue homeostasis, even in the absence of aggression, interacting with the tissue cells and allowing the functional maintenance of that tissue. One of the main cells known for their function in helping the immune response through the production of cytokines is CD4+ T lymphocytes. The cytokines produced by the different subtypes act not only on immune cells but also on tissue cells. Considering that tissues have specific mediators in their architecture, it is plausible that the presence and frequency of CD4+ T lymphocytes of specific subtypes (Th1, Th2, Th17, and others) maintain tissue homeostasis. In situations where homeostasis is disrupted, such as infections, allergies, inflammatory processes, and cancer, local CD4+ T lymphocytes respond to this disruption and, as in the healthy tissue, towards the equilibrium of tissue dynamics. CD4+ T lymphocytes can be manipulated by tumor cells to promote tumor development and metastasis, making them a prognostic factor in various types of cancer. Therefore, understanding the function of tissue-specific CD4+ T lymphocytes is essential in developing new strategies for treating tissue-specific diseases, as occurs in cancer. In this context, this article reviews the evidence for this hypothesis regarding the phenotypes and functions of CD4+ T lymphocytes and compares their contribution to maintaining tissue homeostasis in different organs in a steady state and during tumor progression.

EGFR marks a subpopulation of dermal mesenchymal cells highly expressing IGF1 which enhances hair follicle regeneration

The skin harbours transcriptionally and functionally heterogeneous mesenchymal cells that participate in various physiological activities by secreting biochemical cues. In this study, we aimed to identify a new subpopulation of dermal mesenchymal cells that enhance hair follicle regeneration through a paracrine mechanism. Integrated single-cell RNA sequencing (scRNA-seq) data analysis revealed epidermal growth factor receptor (EGFR) as a marker of distinct fibroblast subpopulation in the neonatal murine dermis. Immunofluorescence staining and fluorescence-activated cell sorting (FACS) were used to validate the existence of the cell population in Krt14-rtTA-H2BGFP mouse. The difference of gene expression between separated cell subpopulation was examined by real-time PCR. Potential effect of the designated factor on hair follicle regeneration was observed after the application on excisional wounds in Krt14-rtTA-H2BGFP mouse. Immunofluorescence staining demonstrated the existence of dermal EGFR+ cells in neonatal and adult mouse dermis. The EGFR+ mesenchymal population, sorted by FACS, displayed a higher expression level of Igf1 (insulin-like growth factor 1). Co-localisation of IGF1 with EGFR in the mouse dermis and upregulated numbers of hair follicles in healed wounds following the application of exogenous IGF1 illustrated the contribution of EGFR+ cells in promoting wound-induced hair follicle neogenesis. Our results indicate that EGFR identifies a subpopulation of dermal fibroblasts that contribute to IGF1 promotion of hair follicle neogenesis. It broadens the understanding of heterogeneity and the mesenchymal cell function in skin and may facilitate the potential translational application of these cells.

Therapeutic role of growth factors in treating diabetic wound

Wounds in diabetic patients, especially diabetic foot ulcers, are more difficult to heal compared with normal wounds and can easily deteriorate, leading to amputation. Common treatments cannot heal diabetic wounds or control their many complications. Growth factors are found to play important roles in regulating complex diabetic wound healing. Different growth factors such as transforming growth factor beta 1, insulin-like growth factor, and vascular endothelial growth factor play different roles in diabetic wound healing. This implies that a therapeutic modality modulating different growth factors to suit wound healing can significantly improve the treatment of diabetic wounds. Further, some current treatments have been shown to promote the healing of diabetic wounds by modulating specific growth factors. The purpose of this study was to discuss the role played by each growth factor in therapeutic approaches so as to stimulate further therapeutic thinking.

Biomarkers of Skin Graft Healing in Venous Leg Ulcers

There is a need for biomarkers that predict the success of transplantation of venous leg ulcers (with autologous split-thickness skin grafts). The primary objective of this exploratory study was to investigate the association between split-thickness skin graft healing in venous leg ulcers and candidate wound fluid biomarkers representing inflammatory cell and endogenous proteinase activities, and bioactivity. A secondary objective was to compare biomarker levels of the 17 venous leg ulcers with sterile split-thickness skin graft donor-site wounds in another 10 patients with venous leg ulcers. Wound fluids were collected for 24 h using a validated method. The concentration of pre-operative matrix metalloproteinase-9 in wound fluid was higher in venous leg ulcers showing good healing (n = 10) than in venous leg ulcers showing poor healing (n = 7) 12 weeks after transplantation with meshed split-thickness skin grafts. The diagnostic value of matrix metalloproteinase-9 was good according to receiver-operating characteristic curve analysis. Matrix metalloproteinase activity in wound fluids from split-thickness skin graft donor-site wounds increased as a function of time and healing, but was still lower than matrix metalloproteinase activity in venous leg ulcer wound fluids, which showed increased levels of most biomarkers except for matrix metalloproteinase-9 and matrix metalloproteinase-2. In conclusion, wound fluid matrix metalloproteinase-9 concentration is a potential predictive biomarker of split-thickness skin graft healing in venous leg ulcers.

Cytokines and Venous Leg Ulcer Healing-A Systematic Review

Venous leg ulcers (VLUs) are the most common type of leg ulcers with a significant socioeconomic burden due to slow healing. Cytokines may be involved in the pathogenesis of VLUs. In this systematic review, our objective was to investigate the association between cytokine levels, including growth factors, with the healing of VLUs. PubMed, Embase, Web of Science and Cochrane Library were searched from their inception to August 2021. We retrieved 28 articles investigating 38 different cytokines in 790 patients. Cytokines were most commonly investigated in wound fluid and less frequently in biopsies and serum. The studies were judged as having a moderate to high risk of bias, and the results were often inconsistent and sometimes conflicting. A meta-analysis was not performed due to clinical and methodological heterogeneities. We found weak evidence for elevated IL-1α, IL-6, IL-8, TNF-α and VEGF levels in non-healing VLUs, an elevation that declined with healing. TGF-β1 levels tended to increase with VLU healing. Other cytokines warranting further investigations include EGF, FGF-2, GM-CSF, IL-1β, IL-1Ra and PDGF-AA/PDGF-BB. We conclude that non-healing VLUs may be associated with an elevation of a palette of pro-inflammatory cytokines, possibly reflecting activated innate immunity in these wounds. There is a paucity of reliable longitudinal studies monitoring the dynamic changes in cytokine levels during wound healing.

Wound fluid sampling methods for proteomic studies: A scoping review

Understanding why some wounds are hard to heal is important for improving care and developing more effective treatments. The method of sample collection used is an integral step in the research process and thus may affect the results obtained. The primary objective of this study was to summarise and map the methods currently used to sample wound fluid for protein profiling and analysis. Eligible studies were those that used a sampling method to collect wound fluid from any human wound for analysis of proteins. A search for eligible studies was performed using MEDLINE, Embase and CINAHL Plus in May 2020. All references were screened for eligibility by one reviewer, followed by discussion and consensus with a second reviewer. Quantitative data were mapped and visualised using appropriate software and summarised via a narrative summary. After screening, 280 studies were included in this review. The most commonly used group of wound fluid collection methods were vacuum, drainage or use of other external devices, with surgical wounds being the most common sample source. Other frequently used collection methods were extraction from absorbent materials, collection beneath an occlusive dressing and direct collection of wound fluid. This scoping review highlights the variety of methods used for wound fluid collection. Many studies had small sample sizes and short sample collection periods; these weaknesses have hampered the discovery and validation of novel biomarkers. Future research should aim to assess the reproducibility and feasibility of sampling and analytical methods for use in larger longitudinal studies.

Polymer-Based Nanotherapeutics for Burn Wounds

Burn wounds are complex and intricate injuries that have become a common cause of trauma leading to significant mortality and morbidity every year. Dressings are applied to burn wounds with the aim of promoting wound healing, preventing burn infection and restoring skin function. The dressing protects the injury and contributes to recovery of dermal and epidermal tissues. Polymer-based nanotherapeutics are increasingly being exploited as burn wound dressings. Natural polymers such as cellulose, chitin, alginate, collagen, gelatin and synthetic polymers like poly (lactic-co-glycolic acid), polycaprolactone, polyethylene glycol, and polyvinyl alcohol are being obtained as nanofibers by nanotechnological approaches like electrospinning and have shown wound healing and re-epithelialization properties. Their biocompatibility, biodegradability, sound mechanical properties and unique structures provide optimal microenvironment for cell proliferation, differentiation, and migration contributing to burn wound healing. The polymeric nanofibers mimic collagen fibers present in extracellular matrix and their high porosity and surface area to volume ratio enable increased interaction and sustained release of therapeutics at the site of thermal injury. This review is an attempt to compile all recent advances in the use of polymer-based nanotherapeutics for burn wounds. The various natural and synthetic polymers used have been discussed comprehensively and approaches being employed have been reported. With immense research effort that is currently being invested in this field and development of proper characterization and regulatory framework, future progress in burn treatment is expected to occur. Moreover, appropriate preclinical and clinical research will provide evidence for the great potential that polymer-based nanotherapeutics hold in the management of burn wounds.

Insulin-like growth factor-I and wound healing, a potential answer to non-healing wounds: A systematic review of the literature and future perspectives

The induction of wound healing by insulin-like growth factor-I (IGF-I) has been demonstrated in several animal studies; however, there are disproportionately fewer studies assessing its value in humans. The aim of the present review is to provide a comprehensive summary of all the available evidence pertaining to the effects of IGF-I administration on the process of wound anaplasias, both in human tissues in vivo and in cells in vitro. A systematic search of Medline, Scopus and Google Scholar was performed for relevant studies published until May 2020. Overall, 11 studies were included. Of these, 2 studies were conducted in human subjects, whereas the rest of them were performed using in vitro models of human cell lines. All studies demonstrated a positive association between IGF-I and wound anaplasias; IGF-I promoted the migration of keratinocytes, thus playing an important role in wound epithelialization as well as enabling wound bed contraction, and it also stimulated hyaluronan synthesis. The wound healing-promoting effect of IGF-I may be a great asset in dealing with the healing of challenging wounds; thus, this type of treatment could be extremely useful in addressing patients with large burn wounds, chronic diabetic ulcers and patients with impaired wound healing. Nevertheless, the route of recombinant IGF-I administration, the recommended dosage, as well as the indications for clinical use of this growth factor remain to be determined and thus, additional clinical trials are required, with a focus on the medical use of recombinant IGF-I in wound anaplasias.

Platelet-rich Plasma and Cell Therapy: The New Horizon in Hair Loss Treatment

Current medicinal therapies for treating hair loss have shortcomes due to variability and ineffectiveness, noncompliance, and adverse effects. The prevalence of hair loss and its associated negative psychological impact have driven research into regenerative medicine approaches, such as platelet-rich plasma (PRP) and cell-based therapies, in an attempt to find alternative, safe, effective, and reproducible treatments. Current research shows promising results from these therapies; however, more robust trials are needed to confirm the reported efficacies of PRP and cell-based therapies. Moreover, standardization of treatment preparation as well as dose and regimen are needed.

YKL-40 A Sensitive Biomarker for Early Androgenetic Alopecia and Early Hidden Metabolic Syndrome

Background:

Androgenetic alopecia (AGA) is a common dermatological problem, Does the onset of the AGA matters in the general health? YKL 40 may have role in the pathogenesis of early AGA and associated metabolic syndrome (MS). YKL 40, released by many inflammatory cells and its biological role is not well known.

Aim of the Work:

The estimation of serum level of YKL-40 in patients with AGA to detect its role in AGA and MS pathogenesis, onset and severity.

Materials and Methods:

This case–control study, 100 individuals were enrolled in our study; 70 AGA patients and 30 healthy controls. We obtained an informed written consent from each individual prior the participation. AGA was diagnosed clinically, and onset was evaluated as early onset alopecia (by the age of 30 years or earlier), YKL-40 level was measured by ELISA technique.

Results:

Patients showed highly significant higher serum YKL-40 level more than that of the healthy subjects (P < 0.001). There was highly significant increase in YKL-40 level among early onset male and female cases compared to late onset cases (P < 0.001 each). There was significant increase in MS elements in AGA cases than controls (P < 0.05), and highly significant increase in MS associations and severity among early onset male and female cases compared to late onset cases (P < 0.001 each). AGA patients with MS showed highly significant higher serum YKL-40 level more than that without (P < 0.001). There was highly significant increase in YKL-40 level among early onset AGA with MS compared to late onset cases with MS (P < 0.001 each).

Conclusions:

High serum YKL-40 considered not only a biomarker of early onset AGA but also considered a potential sensitive predictor for early onset MS development and severity in patients with early onset AGA.

Dermoscopic pre- and posttreatment evaluation in patients with androgenetic alopecia on platelet-rich plasma-A prospective study

BACKGROUND

Platelet-rich plasma is rich in growth factors that promote differentiation and growth of dermal papilla cells by various signaling pathways. Dermoscopy is handy, bedside tool that helps to improve diagnostic accuracy in various hair disorders.

OBJECTIVES

To evaluate and study the role of dermoscopy in patients with androgenetic alopecia (AGA) pre- and posttreatment with platelet-rich plasma (PRP).

METHODS

It is a prospective comparative study. Twenty male patients with AGA, aged 18-45 years with modified Norwood-Hamilton classification grade II-VI were included in this study. Patients were given platelet-rich plasma injections every 3 week for a period of 3 months. Dermoscopy was performed with 10 x magnifications in polarized mode at baseline and at 3 months from the baseline and photographs were taken. Patients were evaluated based on following dermoscopic findings (a) hair count, (b) hair density, (c) hair diameter diversity, perifollicular pigmentation, yellow dots, multi-hair follicular units, honeycomb pigment pattern and white dots, (d) patient's hair growth assessment score.

RESULTS

Posttherapy, patients showed significant improvement in hair count (27.4%), hair diversity (84.2%), increase in number of thick, terminals hairs, reduction in yellow dots (60%), perifollicular pigmentation (92.3%) was appreciated. Hair pull test negative after treatment in 10 patients (50%). Patient's hair growth assessment score showed 50%-75% improvement in 7 (35%) patients.

CONCLUSION

Dermoscopy helps to easily evaluate and compare the therapeutic response pre- and posttreatment which can be easily documented and visualized at every visit.

[The semi-occlusive dressing in treating Allen III and IV fingertip injuries as an alternative to local skin flaps]

BACKGROUND

Fingertip injuries are very common in emergency departments. According to the literature, Allen III and IV fingertip injuries should be treated with local skin flaps. Instead, we have treated these kinds of injuries in recent years with a semi-occlusive dressing. The main purpose of this study was to evaluate the outcome after semi-occlusive dressing therapy with respect to soft tissue cover, recovery of sensibility and duration of disability.

METHODS

We retrospectively analysed 77 fingertip injuries (39 Allen I, 25 Allen II, 9 Allen III, 4 Allen IV) from 2008-2011 in 23 women and 54 men who were treated with a semi-occlusive dressing. The mean age was 36 ± 14 years and the mean follow-up was seven months. The bone was not shortened even if the bone was exposed up to the wound level. The primarily occlusive dressing was left as long as possible and was sealed when necessary. Furthermore, the treatment time with the semi-occlusive dressing and the period of disability was recorded. Patient sensitivity recovery was also analysed.

RESULTS

The mean treatment duration was 21 ± 10 days and the mean duration of disability was 30 ± 17 days. The mean duration of disability was 19 ± 8 days for Allen I injuries, 36 ± 16 days for Allen II, 45 ± 20 days for Allen III and 58 ± 7 days for Allen IV. All patients developed satisfactory tissue cover and sensibility recovery. For amputation injuries of Allen III and IV, we recorded a normal light-touch 2‑point discrimination in the Semmes-Weinstein Test in 77 % and diminished in 23 %. There were no complications like tissue infections, neuroma or osteitis. Also, no secondary flap supply was necessary.

CONCLUSIONS

The semi-occlusive dressing is a good therapy for all kind of fingertip injuries, regardless of the amputation level. Even if the bone is exposed up to the wound level, satisfactory soft tissue cover can be achieved.

Local Growth Hormone Therapy for Pressure Ulcer Healing on a Human Skin Mouse Model

The growth hormone is involved in skin homeostasis and wound healing. We hypothesize whether it is possible to improve pressure ulcer (PU) healing by locally applying the recombinant human growth hormone (rhGH) in a human skin mouse model. Non-obese diabetic/severe combined immunodeficient mice (n = 10) were engrafted with a full-thickness human skin graft. After 60 days with stable grafts, human skin underwent three cycles of ischemia-reperfusion with a compression device to create a PU. Mice were classified into two groups: rhGH treatment group (n = 5) and control group (n = 5). In the rhGH group for local intradermal injections, each had 0.15 mg (0.5IU) applied to the PU edges, once per week for four weeks. Evaluation of the wound healing was conducted with photographic and visual assessments, and histological analysis was performed after complete wound healing. The results showed a healing rate twice as fast in the rhGH group compared to the control group (1.25 ± 0.33 mm2/day versus 0.61 ± 0.27 mm2/day; p-value < 0.05), with a faster healing rate during the first 30 days. The rhGH group showed thicker skin (1953 ± 457 µm versus 1060 ± 208 µm; p-value < 0.05) in the repaired area, with a significant decrease in collagen type I/III ratio at wound closure (62 days, range 60-70). Local administration of the rhGH accelerates PU healing in our model. The rhGH may have a clinical use in pressure ulcer treatment.

Nanopharmaceuticals for wound healing - Lost in translation?

Today, many of the newly developed pharmaceuticals and medical devices take advantage of nanotechnology and with a rising incidence of chronic diseases such as diabetes and cardiovascular disease, the number of patients afflicted globally with non-healing wounds is growing. This has created a requirement for improved therapies and wound care. However, converting the strategies applied in early research into new products is still challenging. Many of them fail to comply with the market requirements. This review discusses the legal and scientific challenges in the design of nanomedicines for wound healing. Are they lost in translation or is there a new generation of therapeutics in the pipeline?

Perioperative warming, oxygen, and Ilomedin on oxygenation and healing in infrainguinal bypass surgery

BACKGROUND

Perioperative adjuncts are utilized across surgical specialities with the goal of improving patient outcomes. High-dose oxygen and extended warming are shown to increase wound collagen deposition during abdominal surgery. Prostacyclin is shown to improve limb salvage and patency rate in infrainguinal bypass (IIB) surgery. This study evaluated the impact of these adjuncts on healing and perfusion post IIB surgery.

METHODS

This randomized controlled study allocated patients undergoing IIB surgery into three treatment arms (perioperative high-dose oxygen, extended warming, and a synthetic prostacyclin) or a control group. The primary outcome was accumulation of hydroxyproline (OHP, collagen surrogate marker) as collected in polytetrafluoroethylene implants on day 5. Secondary outcomes included levels of growth factors and cytokines, and tissue oxygenation of the wound and foot as measured by hyperspectral technology and ankle-brachial pressure index. Clinical outcomes were observed to day 30, with long-term follow-up of 12 mo.

RESULTS

Seventy-one patients completed the study. Comparing treatment groups with the control at day 5, there were no differences in OHP, growth factors or cytokines levels, or improvement in tissue oxygenation at the surgical incision. However, there was more flow to the foot (HT-SUM (%) change) in the Ilomedin group compared to control (0% versus -14.6%, P = 0.045). HT-deoxy was higher at the peripheries in the oxygen and temperature groups, suggesting decreased tissue oxygenation.

CONCLUSIONS

The perioperative treatments did not dramatically improve oxygenation or healing of the surgical wound in IIB surgery; however, Ilomedin may result in greater flow to the peripheries.

Platelet-rich Plasma by Single Spin Process in Male Pattern Androgenetic Alopecia: Is it an Effective Treatment?

Introduction and Objective:

Platelet-rich plasma (PRP) is an autologous preparation of platelets in concentrated plasma. The platelet is a natural source of different growth factors and cytokines. These growth factors act on stem cells in the bulge area of the follicles and stimulate the development of new follicles, and promote neovascularization. The aim of this study was to investigate the efficacy and safety of PRP injections in androgenetic alopecia (AGA) in men.

Patients and Methods:

Fifteen male patients (mean age: 39 ± 9.7 years) with AGA grades III–VI were enrolled in the study. Five injections of 2–4 ml PRP (Regenlab PRP Kit-RegenACR®, Le Mont-sur-Lausanne Switzerland) by single spin process were administered every 2 weeks. Standard photographs, trichogram, and measurement of hair density and diameter in an area marked with a tattoo (with digital photographic hair analyzer) were done at baseline and 3 months after the last injection. In addition, patients completed a patient satisfaction questionnaire at each visit on a −2 to +2 score (−2: much worse, −1: slightly worse, 0: without change, +1: slightly better, +2: much better).

Results:

Thirteen patients completed the study. The number of hairs increased slightly from 149.62 ± 49.56 to 168.46 ± 43.703/cm², however, this increase was not statistically significant (P = 0.24). On the other hand, the thickness of hairs decreased from 0.051 ± 0.105 to 0.045 ± 0.011 mm, which was also not significant (P = 0.37). There was a significant decrease in anagen hairs and increase in telogen hairs, and anagen/telogen ratio decreased significantly from 6.38 ± 4.57 to 2.67 ± 1.87 (P = 0.003).

Conclusion:

Our study could not show any benefit from PRP injections in the treatment of male AGA. There is a strong need for well-designed, randomized controlled trials with large sample size, proper control group, standard treatment protocols (concerning the amount, number and interval of PRP injections, method of preparation and activation, etc.), and long follow-up periods to evaluate the safety and efficacy of PRP in the treatment of male AGA.

Platelet gel: a new therapeutic tool with great potential

Chronic wounds, such as diabetic foot ulcers, represent a serious clinical problem for patients and clinicians. Management of these wounds has a strong economic impact worldwide. Complications resulting from injuries are a frequent cause of morbidity and mortality. Chronic wounds lead to infections, painful dressings and prolonged hospitalisation. This results in poor patient Quality of Life and in high healthcare costs. Platelet concentrates (PC) are defined as autologous or allogeneic platelet derivatives with a platelet concentration higher than baseline. PC are widely used in different areas of Regenerative Medicine in order to enhance wound healing processes; they include platelet-rich plasma (PRP), platelet gel (PG), platelet-rich fibrin (PRF), serum eye drops (E-S), and PRP eye drops (E-PRP). This review highlights the use of platelet-rich plasma (PRP) and platelet gel (PG) preparation for clinical use.

Plastic chronic wound management with Cellutome

Chronic wounds continue to present a significant challenge to health-care providers around the globe. Unlike acute wounds, chronic wounds do not proceed through an orderly process of repair. In recent years many new modalities of modern wound treatment systems have been promoted. However, until recently there were few modalities designed to promote epithelialisation of a fully granulated wound. Mesh graft procedures have long been the gold standard for the management of acute wounds and chronic wounds but have also many disadvantages like discomfort associated with the donor site and the creation of a second painful wound (donor site).

The increase of chronical wounds in Germany due to the average age of patients, the aggressiveness of medical treatment and increase of numbers of patients with diabetes and severe polymorbidity requires specialized wound treatment and plastic surgery. Since 2014 there was a new innovative system introduced in the market called Cellutome epidermal harvesting system. The Cellutome system is a epidermal harvesting system for skin grafting and can replace in many cases the traditional meshgraft procedure with a classic dermatoma. The skin donor section on the patient`s thigh heals within days without scarring. The system offers a precise, simplified and minimal invasive option for skin grafting in the treatment of especially chronic wounds.

Understanding regulatory pathways of neovascularization in diabetes

Diabetes mellitus and its associated comorbidities represent a significant health burden worldwide. Vascular dysfunction is the major contributory factor in the development of these comorbidities, which include impaired wound healing, cardiovascular disease and proliferative diabetic retinopathy. While the etiology of abnormal neovascularization in diabetes is complex and paradoxical, the dysregulation of the varied processes contributing to the vascular response are due in large part to the effects of hyperglycemia. In this review, we explore the mechanisms by which hyperglycemia disrupts chemokine expression and function, including the critical hypoxia inducible factor-1 axis. We place particular emphasis on the therapeutic potential of strategies addressing these pathways; as such targeted approaches may one day help alleviate the healthcare burden of diabetic sequelae.

Clinical application of growth factors and cytokines in wound healing

Wound healing is a complex and dynamic biological process that involves the coordinated efforts of multiple cell types and is executed and regulated by numerous growth factors and cytokines. There has been a drive in the past two decades to study the therapeutic effects of various growth factors in the clinical management of nonhealing wounds (e.g., pressure ulcers, chronic venous ulcers, diabetic foot ulcers). For this review, we conducted an online search of Medline/PubMed and critically analyzed the literature regarding the role of growth factors and cytokines in the management of these wounds. We focused on currently approved therapies, emerging therapies, and future research possibilities. In this review, we discuss four growth factors and cytokines currently being used on and off label for the healing of wounds. These include granulocyte-macrophage colony-stimulating factor, platelet-derived growth factor, vascular endothelial growth factor, and basic fibroblast growth factor. While the clinical results of using growth factors and cytokines are encouraging, many studies involved a small sample size and are disparate in measured endpoints. Therefore, further research is required to provide definitive evidence of efficacy.

The involvement of PDGF/VEGF related factor in regulation of immune and neuroendocrine in Chinese mitten crab Eriocheir sinensis

Members of the platelet-derived growth factor/vascular endothelial growth factor (PDGF/VEGF) family have been implicated in cell proliferation, cell differentiation, and cell migration, vascular development, angiogenesis and neural development. In the present study, a novel PDGF/VEGF related factor gene was cloned and identified in Chinese mitten crab Eriocheir sinensis (designated as EsPVF1). The full-length cDNA of EsPVF1 was of 1173 bp, consisting a 5' untranslated region (UTR) of 54 bp, a 3' UTR of 1131 bp with a poly (A) tail, and an open reading frame (ORF) of 588 bp encoding 196 amino acid residues. A signal peptide of 20 amino acid residues, a PDGF/VEGF homology growth factor domain of 81 amino acids, and a typical cysteine knot motif (CXCXC) were identified in the deduced amino acid sequence of EsPVF1. By fluorescent quantitative real-time PCR, the EsPVF1 mRNA was detected ubiquitously in the select tissues of hemocytes, gonad, heart, muscle, hepatopancreas and gill, with the high abundance in hemocytes and gonad. The mRNA expression level of EsPVF1 was up-regulated and reached the highest at 24 h after Vibrio anguillarum challenge, while it was induced at 3 h, 6 h, 12 h, 24 h and 48 h compared with the untreated group after Pichia pastoris GS115 challenge. Tissue injury also induced the mRNA expression of EsPVF1 in hemocytes of crabs, and the expression level increased obviously at 8 h. The cDNA fragment encoding mature peptide of EsPVF1 was recombined and expressed in Escherichia coli BL21 (DE3) pLysS. Biogenic amine in hemolymph pre-incubated with recombinant protein of EsPVF1 (rEsPVF1) was detected by fluorimetric method. Norepinephrine and dopamine in hemolymph incubated with rEsPVF1 were higher than that in the blank group. Therefore, EsPVF1 could significantly provoke the release of norepinephrine and dopamine. The results collectively indicated that EsPVF1 was involved in regulation of the immune response and neuroendocrine system in crabs.

Wound Fluid in Diabetic Foot Ulceration

Valid and reproducible sampling techniques as well as processing protocols are required for the assessment of biomarkers and mediators contained in wound exudate. Moreover, the ideal technique should be easy to use even in daily clinical routine. This is challenging since wound fluid represents an inhomogeneous mixture of different exogenous and endogenous sources. Analyzing wound fluid, however, may facilitate clinical decision making. Many techniques for obtaining wound fluid have been described. There is very little validation data, and the array of different techniques appears confusing. Structuring and new standards are needed to avoid wound fluid sampling yielding an “undefined soup.” A lot of wound fluid parameters have been analyzed, although none of them have made its way into clinical practice. Nevertheless, basic principles of wound healing have been established from wound fluid analysis. With adequate techniques suitable for daily practice, basic research might foster our clinical understanding of wound healing with implications for new therapies. So far, research has mainly concentrated on analyzing available sample material with respect to either a wide variety of analytes or comparing acute with chronic wound exudate. Clinical endpoints such as healing or wound infection as well as longitudinal data may indeed be more valuable for clinical practice, enabling the discovery of meaningful biomarkers using a suitable technique.

Intradermal adipocytes mediate fibroblast recruitment during skin wound healing

Acute wound healing in the skin involves the communication of multiple cell types to coordinate keratinocyte and fibroblast proliferation and migration for epidermal and dermal repair. Many studies have focused on the interplay between hematopoietic cells, keratinocytes and fibroblasts during skin wound healing, yet the possible roles for other cell types within the skin, such as intradermal adipocytes, have not been investigated during this process. Here, we identify that adipocyte lineage cells are activated and function during acute skin wound healing. We find that adipocyte precursor cells proliferate and mature adipocytes repopulate skin wounds following inflammation and in parallel with fibroblast migration. Functional analysis of mice with defects in adipogenesis demonstrates that adipocytes are necessary for fibroblast recruitment and dermal reconstruction. These data implicate adipocytes as a key component of the intercellular communication that mediates fibroblast function during skin wound healing.

Growth hormone system: skin interactions

This paper describes the growth hormone system, emphasizing its possible effects on epidermal cells, dermal structures and wound healing. A review of the literature was conducted on studies concerning the growth hormone molecule, its receptor and carrier proteins and the other proteins involved in the mechanisms of its manifestation in dermal tissue.

Full-thickness skin wound healing using human placenta-derived extracellular matrix containing bioactive molecules

The human placenta, a complex organ, which facilitates exchange between the fetus and the mother, contains abundant extracellular matrix (ECM) components and well-preserved endogenous growth factors. In this study, we designed a new dermal substitute from human placentas for full-thickness wound healing. Highly porous, decellularized ECM sheets were fabricated from human placentas via homogenization, centrifugation, chemical and enzymatic treatments, molding, and freeze-drying. The physical structure and biological composition of human placenta-derived ECM sheets dramatically supported the regeneration of full-thickness wound in vivo. At the early stage, the ECM sheet efficiently absorbed wound exudates and tightly attached to the wound surface. Four weeks after implantation, the wound was completely closed, epidermic cells were well arranged and the bilayer structure of the epidermis and dermis was restored. Moreover, hair follicles and microvessels were newly formed in the ECM sheet-implanted wounds. Overall, the ECM sheet produced a dermal substitute with similar cellular organization to that of normal skin. These results suggest that human placenta-derived ECM sheets provide a microenvironment favorable to the growth and differentiation of cells, and positive modulate the healing of full-thickness wounds.

Enhanced random skin flap survival by sustained delivery of fibroblast growth factor 2 in rats

BACKGROUND

Skin flap survival is a major challenge in reconstructive plastic surgery. Here, we examined the effect of sustained delivery of fibroblast growth factor 2 (FGF2) using heparin-conjugated fibrin (HCF) on skin flap survival in rats.

METHODS

Rats with a skin flap received either phosphate-buffered saline/FGF2 or HCF/FGF2 in the recipient bed. For the no-treatment group, a random skin flap was sutured on the back without any treatment. Seven days after surgery, angiogenesis in the skin flap was evaluated by using Visitrak system and conventional healing quality scoring method. The efficacy of HCF/FGF2 in skin flap survival was evaluated by comparing the results from different groups.

RESULTS

The necrotic area of the skin flap significantly decreased in the HCF/FGF2 group as compared with the other groups.

CONCLUSION

The sustained delivery of FGF2 using HCF has a therapeutic potential to improve skin flap survival.

Harnessing growth factors to influence wound healing

Cutaneous wound healing is a dynamic process with the ultimate goal of restoring skin integrity. On injury to the skin, inflammatory cells, endothelial cells, fibroblasts, and keratinocytes undergo changes in gene expression and phenotype, leading to cell proliferation, migration, and differentiation. Cytokines and growth factors play an essential role in initiating and directing the phases of wound healing. These signaling peptides are produced by a variety of cells and lead to a concerted effort to restore the skin barrier function.

Features of wound healing shown by fibroblasts obtained from the superficial and deep dermis

Dermal fibroblasts (DF) obtained from the superficial dermal layer and those from the deep dermal layer have different cellular functions. These differences are often associated with excessive scarring; they also influence early wound healing. We therefore investigated the differences between superficial and deep dermal fibroblasts with special emphasis on their contractile properties, and ability to produce connective tissue. We investigated their proliferation kinetics, ability to contract collagen lattices, and chronological mRNA expression of eight genes associated with wound healing. To estimate the changes in the differences between them during the early phase of wound healing, we investigated mRNA expression in bFGF supplemented medium because bFGF is a representative cytokine that is familiar to clinicians. Superficial DF proliferate faster than deep DF in culture, whereas deep DF are better at contracting collagen lattices than superficial ones. In realtime analysis of polymerase chain reaction, the expression of type I and III collagen, fibronectin, TGF β1 and β3, and connective tissue growth factor were higher in deep DF than in superficial DF, while the expression of TGF β2 was higher in superficial DF. After bFGF supplementation, the relative dominance of mRNA expression between superficial and deep DF remained constant except for the expression of collagenase. According to our analysis, deep DF are superior to superficial DF at promoting wound healing (particularly contraction and production of connective tissue). The intradermal distribution of DF is appropriate for efficient wound healing.

Peripheral sensitization caused by insulin-like growth factor 1 contributes to pain hypersensitivity after tissue injury

Sensitization of primary afferent neurons is one of the most important components of pain hypersensitivity after tissue injury. Insulin-like growth factor 1 (IGF-1), involved in wound repair in injured tissue, also plays an important role in maintaining neuronal function. In the present study, we investigated the effect of tissue IGF-1 on nociceptive sensitivity of primary afferent neurons. Local administration of IGF-1 induced thermal and mechanical pain hypersensitivity in a dose-dependent manner, and was attenuated by IGF-1 receptor (IGF1R) inhibition. Tissue but not plasma IGF-1 levels, as determined by enzyme-linked immunosorbent assay, significantly increased after plantar incision. Immunohistochemistry revealed that IGF1R was predominantly expressed in neurons as well as in satellite glial cells in the dorsal root ganglion (DRG). Double-labeling immunohistochemistry showed that IGF1R expression colocalized with peripherin and TRPV1, but not with NF200 in DRG neurons. The IGF1R inhibitor successfully alleviated mechanical allodynia, heat hyperalgesia, and spontaneous pain behavior observed after plantar incision. Expression of phosphorylated Akt in DRG neurons significantly increased after plantar incision and was suppressed by IGF1R inhibition. These results demonstrate that increased tissue IGF-1 production sensitizes primary afferent neurons via the IGF1R/Akt pathway to facilitate pain hypersensitivity after tissue damage.

Relationship between lymphangiogenesis and exudates during the wound-healing process of mouse skin full-thickness wound

We considered the relationship among exudate, wound area, angiogenesis, lymphangiogenesis, and reepithelialization during wound healing. Full-thickness wounds were made on the dorsum of mice. The weight of exudate absorbed into the dressing as well as the wound area was determined daily. Sections of the wounds were stained with anti-LYVE-1 and CD31 antibodies. Indian ink was injected into the wound for observing the movement of the exudate on days 3, 5, and 7 after wounding. New epithelium completely covered the wound on day 11. The quantity of exudate peaked on day 1, and then rapidly decreased until it was undetectable on day 11. Most of the Indian ink injected into the wound was retained within the wound and did not flow into the surrounding tissue. New blood vessels showed a uniform distribution in the granulation tissue on day 5. New lymphatics appeared in the granulation tissue approximately 2 days later than the blood vessels and they were distributed toward the center of the granulation tissue on day 11. Thus, reduction of exudate from the wound appears to be related to blood vessels, not lymphatics. However, increasing lymphatics may play a role in the late phase of the wound-healing process.

A role for human skin-resident T cells in wound healing

Epidermal T cells have been shown to play unique roles in tissue homeostasis and repair in mice through local secretion of distinct growth factors in the skin. Human epidermis contains both alphabeta(+) and gammadelta(+) T cells whose functional capabilities are not understood. We demonstrate that human epidermal T cells are able to produce insulin-like growth factor 1 (IGF-1) upon activation and promote wound healing in a skin organ culture model. Moreover, an analysis of the functional capabilities of T cells isolated from acute versus chronic wounds revealed a striking difference. Both alphabeta(+) and Vdelta1(+) T cells isolated from acute wounds actively produced IGF-1, demonstrating that they are activated during tissue damage to participate in wound repair. In contrast, IGF-1 production could not be detected in T cells isolated from chronic wounds. In fact, skin T cells isolated from chronic wounds were refractory to further stimulation, suggesting an unresponsive state. Collectively, these results define a novel role for human epidermis-resident T cells in wound healing and provide new insight into our understanding of chronic wound persistence.

Effect of cytokine growth factors on the prevention of acute wound failure

Cytokine growth factor treatment of chronic wounds has met with mixed results. The chronic wound presents a hostile environment to peptides such as growth factors. Cytokine growth factors have not been studied extensively in acute wounds. However, incisional hernias are a major example of acute wound failure that has not been solved by various mechanical approaches. A biological approach to acute wound failure by use of cytokine growth factors may offer a new strategy. A rodent incisional hernia model was used. Seventy-six rats underwent 3-cm midline celiotomies and were closed with fine, fast-absorbing sutures to induce intentional acute wound failure. Group 1 received no other treatment. The midline fascia in Groups 2-10 was infiltrated with 100 microl of vehicle alone or vehicle containing various test cytokine growth factors. Necropsy was performed on postoperative day 28 and the wounds were examined for herniation. Incisional hernias developed in 83 percent (13/16) of untreated incisional and 88 percent (7/8) and 83 percent (5/6) of the two vehicle-treated incisions (PBS and carboxymethylcellulose). Hernia incidences were decreased by priming of the fascial incision with transforming growth factor-beta(2) (12%, 1/8), basic fibroblast growth factor (25%, 2/8) and interleukin-1 beta (50%, 3/6) (p < 0.05). Aqueous platelet-derived growth factor, becaplermin, insulin-like growth factor, and granulocyte macrophage-colony stimulating factor did not significantly decrease the incidence of acute wound failure (p > 0.05). A biological approach to acute wound failure as measured by incisional hernia formation can be useful in reducing the incidence of this complication. Transforming growth factor-beta(2), basic fibroblast growth factor, and interleukin 1 beta all eliminated or significantly reduced the development of incisional hernias in the rat model.

Overexpression of mIGF-1 in keratinocytes improves wound healing and accelerates hair follicle formation and cycling in mice

Insulin-like growth factor 1 (IGF-1) is an important regulator of growth, survival, and differentiation in many tissues. It is produced in several isoforms that differ in their N-terminal signal peptide and C-terminal extension peptide. The locally acting isoform of IGF-1 (mIGF-1) was previously shown to enhance the regeneration of both muscle and heart. In this study, we tested the therapeutic potential of mIGF-1 in the skin by generating a transgenic mouse model in which mIGF-1 expression is driven by the keratin 14 promoter. IGF-1 levels were unchanged in the sera of hemizygous K14/mIGF-1 transgenic animals whose growth was unaffected. A skin analysis of young animals revealed normal architecture and thickness as well as proper expression of differentiation and proliferation markers. No malignant tumors were formed. Normal homeostasis of the putative stem cell compartment was also maintained. Healing of full-thickness excisional wounds was accelerated because of increased proliferation and migration of keratinocytes, whereas inflammation, granulation tissue formation, and scarring were not obviously affected. In addition, mIGF-1 promoted late hair follicle morphogenesis and cycling. To our knowledge, this is the first work to characterize the simultaneous, stimulatory effect of IGF-1 delivery to keratinocytes on two types of regeneration processes within a single mouse model. Our analysis supports the use of mIGF-1 for skin and hair regeneration and describes a potential cell type-restricted action.

Insulin-like growth factor-I in wound healing of rat skin

Growth factors play an important role in orchestrating and enabling the cellular responses required for successful wound healing. In the present study, rat surgical incision was used to investigate insulin-like growth factor-I (IGF-I) expression in skin cells as well as its systemic and cutaneous tissue concentrations during acute phase of wound healing. Thirty two animals were sacrificed at days 2, 3, 5 and 9 after surgery. Eight animals were used as control. Tissue expression of IGF-I in both incisional and periincisional skin areas, as well as in skin of control unwounded animals was determined by immunohistochemistry. Serum and tissue concentrations of IGF-I were measured using RIA. Immunohistochemical analysis revealed enhanced IGF-I immunostaining in the incisional area at day 2 post-wounding. Presence of IGF-I immunoreactivity in the epidermis, as well as in dermal fibroblasts and monocytes within perivascular inflammatory infiltrate suggests its local synthesis. Although serum levels of IGF-I were not altered during wound healing, their tissue contents in the incisional area were significantly increased compared with periincisional area at days 2 and 3 after injury, as well as compared with skin content of unwounded control rats in all examined time points. Obtained results support a paracrine role of IGF-I during the acute phase of wound healing by primary intention in the rat.

The extracellular matrix in wound healing: a closer look at therapeutics for chronic wounds

Disappointing results with the use of exogenous recombinant growth factors in chronic wounds have redirected the focus to the extracellular matrix (ECM). Newer research has clearly changed our view on the role of the ECM in tissue repair and dismissed the dogma that the sole function of ECM is a passive physical support for cells. It is now clear that intact or fragmented ECM molecules are capable of transducing signals pivotal for cell processes in wound healing primarily via integrin interactions in concert with growth factor activation. In addition, our knowledge about ECM molecules in minute concentrations with biological activity, but devoid of significant structural influence, is increasing. This article reviews the multifaceted molecular roles of ECM in the normal wound-healing process and some molecular abnormalities in chronic wounds, and touches on potential therapies based on the developments of tissue biology.