Vascular and Collagen Target: A Rational Approach to Hypertrophic Scar Management.

Significance: Hypertrophic scarring is a challenging issue for patients and clinicians. The prevalence of hypertrophic scarring can be up to 70% after burns, and patients suffer from pain, itching, and loss of joint mobility. To date, the exact mechanisms underlying hypertrophic scar formation are unclear, and clinical options remain limited. Recent Advances: Several studies have demonstrated that pathological scars are a type of hyperactive vascular response to wounding. Scar regression has been found to be accompanied by microvessel occlusion, which causes severe hypoxia, malnutrition, and endothelial dysfunction, suggesting the essential roles of microvessels in scar regression. Therefore, interventions that target the vasculature, such as intense pulsed light, pulsed dye lasers, vascular endothelial growth factor antibodies, and Endostar, represent potential treatments. In addition, the mass of scar-associated collagen is usually not considered by current treatments. However, collagen-targeted therapies such as fractional CO2 laser and collagenase have shown promising outcomes in scar treatment. Critical Issues: Traditional modalities used in current clinical practice only partially target scar-associated microvessels or collagen. As a result, the effectiveness of current treatments is limited and is too often accompanied by undesirable side effects. The formation of scars in the early stage is mainly affected by microvessels, whereas the scars in later stages are mostly composed of residual collagen. Traditional therapies do not utilize specific targets for scars at different stages. Therefore, more precise treatment strategies are needed. Future Directions: Scars should be classified as either "vascular-dominant" or "collagen-dominant" before selecting a treatment. In this way, strategies that are vascular-targeted, collagen-targeted, or a combination thereof could be recommended to treat scars at different stages.

Hypertrophic scar regression is linked to the occurrence of endothelial dysfunction.

Most microvessels have been shown to become stenosed or completely occluded during hypertrophic scar progression. Here, we examined the morphology of capillary endothelial cells (ECs) and fibroblasts using immunofluorescence staining for CD31 and alpha-smooth muscle actin (α-SMA) and electron microscopy. In addition, ECs and fibroblasts were isolated from scar tissues, and the levels of transforming growth factor beta 1 (TGF-ß1), platelet-derived growth factor (PDGF), endothelin 1 (ET-1), vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were assayed using ELISAs. Furthermore, we assessed cell viability, total collagen production, and cell apoptosis in hypertrophic scar-derived fibroblasts cultured with EC-conditioned medium. Then, anti-TGF-ß1, anti-PDGF, anti-ET-1, anti-VEGF, and anti-bFGF neutralising antibodies were individually added to the EC medium to identify which growth factor plays a more important role in inhibiting fibroblasts biology. Our results showed microvessel lumen occlusion and EC atrophy during scar development, particularly in regressive scars (RSs). Additionally, EC growth factor secretion decreased and reached the lowest levels in RSs. Furthermore, based on the culture results, RS EC medium inhibited fibroblast viability and collagen production and induced apoptosis. Moreover, TGF-ß1, PDGF, and bFGF played more important roles in these processes than VEGF and ET-1. The endothelial dysfunction occurring in hypertrophic scars contributes to fibroblast inhibition and scar regression, and reduced TGF-ß1, PDGF, and bFGF levels play key roles during this process.

Dynamic hypoxia in scar tissue during human hypertrophic scar progression.

BACKGROUND: The skin color of human hypertrophic scar changes dynamically during scar progression. OBJECTIVE: To investigate whether hypoxia is dynamic during scar progression. METHODS: Thirty-five patients with early, proliferative, regressive, and mature scars were involved in this study. Tissue oxygen tension was measured before scar surgery. After surgery, the scar stage was further defined using hematoxylin and eosin staining, and microvessel density and hypoxia inducible factor-1 (HIF-1) expression were detected using immunohistochemistry to determine a correlation with oxygen level. RESULTS: Mild hypoxia is present in early scars, moderate hypoxia in proliferative scars, and severe hypoxia in regressive scars. Oxygen levels then return to normal in mature scars, which was consistent with the dynamic change in microvessel density. Meanwhile, HIF-1 expression also changed dynamically along with alteration in oxygen levels. CONCLUSION: Hypoxia is dynamic in scar tissue and is possibly correlated with scar formation and regression.

The change of break modulus drives human fibroblast differentiation in 3D collagen gels.

Extracellular matrix is one of the key environmental factors influencing cell survival and provides signals for cell morphological change, migration, proliferation and differentiation. However, the mechanism through which denatured collagen modulates the biological properties of fibroblasts, is unclear. We investigated the regulation of human fibroblast differentiation in vitro grown in collagen gels with different properties. The break modulus of collagen with denatured collagen and half-load normal collagen was reduced compared with that of normal collagen gel. Fibroblasts cultured in denatured collagen gels showed increased expression of matrix metalloproteinase9 ( MMP-9), tissue inhibitor of metalloproteinase 2 (TIMP2), α-smooth muscle actin (α-SMA), osteoblast cadherin, phosphorylated Myosin phosphatase target subunit1 (p-MYPT1), connective tissue growth factor, type I collagen, type III collagen, α-smooth muscle actin messenger RNA, RhoA, rho-associated protein kinase, and transforming growth factor ß receptors 1 and 2 compared with that in cells cultured in normal collagen gel. But there was no significant difference regarding expression level between denatured collagen gel and half-load normal collagen gel .These findings suggest that the change in break modulus caused by decreasing normal collagen concentration may be the key factor inducing fibroblast differentiation.

A severely infected diabetic foot treated successfully without using systemic antibiotics.

About 50% to 70% of all lower extremity amputations are related to diabetes infection. And antibiotic therapy is routinely used for all infected wounds to reduce the mortality of diabetic foot. Here, we report a case of diabetic foot with acute and deep severe infection. During hospital therapy, we used negative pressure therapy and extensive debridement without systemic antibiotic application, and we successfully rescued a foot from amputation. Negative pressure therapy and extensive debridement are very important and effective methods to control infection and promote wound healing in diabetes foot.

A review of the effectiveness of antimitotic drug injections for hypertrophic scars and keloids.

Hypertrophic scars and keloids are common problems after injury and cause functional and cosmetic deformities. A wide variety of treatments have been advocated for hypertrophic scars and keloids regression. Unfortunately, the reported efficacy has been variable. This article explores antimitotic drugs described in the literature such as steroid injection, 5-FU, mitomycin C, and bleomycin, which mainly target the fibroblasts in scar tissue, have been proposed as the effective modalities for scar treatment and scar prevention after surgery, but restricted due to possible side effects. The current accepted treatment for hypertrophic scar and keloid are combination therapy and the early treatment which could achieve better efficacy and less adverse effect.

[The effect of focal-adhesion micromanipulation in trauma and wound healing].

OBJECTIVE: To explore the effect of focal-adhesion micromanipulation on the biological behavior of fibroblast. METHODS: Micro-pot was made by microcontact printing. The molecules of constitutive protein was adhered on micro-pot by self-assemble of peptides. Skin fibroblasts were cultured on the membrane by self-made biomechanical cell culture for 2 weeks. Morphology observation and cell immunohistochemistry analysis was performed. RESULTS: After 2 weeks, the morphology of the fibroblasts was diverse and more compliant. Cell immunohistochemistry analysis found that the expression of integrinbeta1, alpha5 and tensin was dramatically reduced. CONCLUSIONS: The morphology and the biological behaviour of the fibroblasts in hypertrophic scar can be changed after micromanipulation of focal adhesion.

Antimitotic drug injections and radiotherapy: a review of the effectiveness of treatment for hypertrophic scars and keloids.

Scars are a common complication of surgery or burn wound management. Scars occur over the body, affecting people of both sexes and all ages. Scar therapy is a constant clinical challenge; antimitotic drugs and radiotherapy are used with varying degrees of success. This article examines the success of both these types of treatment modalities.

Isolation, culture and characterization of endothelial cells from human hypertrophic scar.

Although the etiology underlying scar formation is not well understood, previous studies revealed that endothelial cells play a role in the pathogenesis of scar development. Recently, the authors developed a reliable technique to obtain endothelial cells from hypertrophic scars that involved separation of cells from the scar tissue matrix and isolation from other cell types. Using phase-contract and electron microscopy, the cells were observed to have a characteristic morphology consistent with cells of endothelial origin. The cells were further characterized as endothelial cells by assessment of endothelin (ET)-1 and intercellular adhesion molecule (ICAM) mRNA expression, and the presence of factor VIII antigen, CD34, CD31, and VE-cadherin. This isolation method provides a simple method for culturing endothelial cells from hypertrophic scar tissue and should prove useful for studying the role of endothelial cell involvement in scar formation.

[Study on the biological function of vascular endothelial cells in the hypertrophic scar].

OBJECTIVE: To explore the biological function of vascular endothelial cells from hypertrophic scar, and to analyze the relationship between them. METHODS: The samples from human hypertrophic scar and normal skin tissue were harvested for histological examination. Then vascular endothelial cells were purified and isolated from the samples, and the level of transforming growth factor (TGF) beta1, platelet derived growth factor (PDGF), endothelin1 (ET)-1, fibroblast growth factor (FGF)2 and vascular endothelial growth factor (VEGF) were determined in a single cell with ELISA. RESULTS: Few capillary vessels were observed in normal skin under microscope, while an increased number of them were present in hypertrophic scar, with slender, tortuous in morphology and even occluded. The diameter of blood capillary in hypertrophic scar was tiny under electron microscope, and the exfoliation of endothelial cells was observed. The levels of TGF-beta1, PDGF, ET-1, bFGF and VEGF from vascular endothelial cells from hypertrophic scar were 60 +/- 8, 30 +/- 4, 0.12 +/- 0.03, 52 +/- 5, 18.1 +/- 1.2 microg/cell, respectively, which were obviously lower than those in normal skin (P < 0.05). CONCLUSION: The biological function of vascular endothelial cells was attenuated in the hypertrophic scar, which mightbe the result of the production of large amounts of collagen in the scar tissue, as well as hypoxia.

[Study on the mechanism of scar formation: epidermis template defect theory].

Dermal defection and the degree of its loss determine the natural process of wound healing, which is the key reason leading to excess scar hyperplasia. The function of tri-dimensional structure in dermis acts as a template to regulate the properties of reparative cells. The template structure induces the reparative cells to grow into the structure which changes the skin mechanic status on wound area. Also, the component of extracellular matrix can affect behaviours of fibroblasts negatively or positively, for the reason that the structure of dermal tissue has a permissive effect on the dermal components in regulating behaviours of reparative cells. Therefore, the behaviors of cells depend on the structure of the template. The suitable tri-dimensional structure of dermis facilitates normal cell cycling. The more the structure of dermis closed to its physiological status, the better the biological behaviors of cells act. Moreover, the integrity as well as the continuity of dermal tissue is the prerequisite for serving as a template. The damage to the integrity and the continuity of dermal tissue may be one of the key reasons to lead abnormal tissue repair and scar formation. Thus, we hypothesize that the loss of dermal template may be one of the mechanism of abnormal scar formation and propose the theory of extracellular matrix framework deficiency or destruction.

[The influence of dermal template on the expressions of signal transduction protein Smad 3 and transforming growth factor beta1 and its receptor during wound healing process in patients with deep burns].

OBJECTIVE: To investigate the influence of dermal template on the expressions of signal transduction protein Smad 3 and transforming growth factor beta1 and its receptor during wound healing process in patients with deep burns. METHODS: Twenty burn patients with excision of full thickness burn in the extremities were enrolled in the study and divided into two groups, i.e. template interfering group (E, n = 20, grafting of dermal template [allogeneic acellular dermal matrix] with razor thin autoskin) and control group (C, n = 20, grafting of razor thin autoskin only). The contralateral side served as the self-control. Tissue samples from the burn wounds were harvested at 1, 2, 3 and 4 post-operative weeks (POW) for immunohistochemistry staining. The positive expression rates of TGF-beta1, TbetaRI, TbetaRII and Smad3 proteins were determined by image analysis system. RESULTS: The positive expressions of TGFbeta1, TbetaRI, TbetaRII and signal transduction protein Smad 3 in the tissue samples in both groups could be identified during 1 approximately 4 POW, and they diminished thereafter with the process of wound healing. The expression rate of TGF-beta1 in E group was (13.08 +/- 4.65)% at 1 POW and (9.03 +/- 1.89)% at 4 POW. The positive expression rate of above indices in E group was obviously lower than that in C group in corresponding time points (P < 0.05). CONCLUSION: The expression levels of TGFbeta1, TbetaRI, TbetaRII and Smad 3 protein in deep burn wounds could be lowered by mixed grafting of dermal template with razor thin autoskin, which might be beneficial in ameliorating of scar hyperplasia in the burn wound.

[The influence of dermal template application on the p53 gene expression and apoptosis during wound repairing in burn patients].

OBJECTIVE: To observe dynamically the influence of the application of dermal template on the p53 gene expression and apoptosis during wound repairing in burn patients. METHODS: Twenty burn patients were enrolled in the study and were divided into experiment (E, n = 11) and control (C, n = 9) groups. The escharectomy wounds in patients with 3rd degree burn in E group were covered with dermal template overlain with thin split-thickness autograft, while those in C group were covered with thin split-thickness autograft only. Specimens were harvested from wounds of both groups at 1st, 2nd, 3rd, 4th and 5th post operative week (POW). The P53 expression and the apoptosis were assessed respectively by immunohistochemistry and by TUNEL kit. The change in cell number was observed after HE staining. RESULTS: The P53 expression increased gradually along with the wound healing process from 1st to 4th POW, which was significantly higher than that in C group at 2nd, 3rd, and 4th POW (P < 0.05), and it reached the peak at 4th POW. Fibroblasts underwent apoptosis at 1st POW in E group, while apoptosis of the endothelial cells occurred mainly at 2nd and 3rd POW. There was obvious difference in the rate of apoptosis between the two groups in 3rd and 4th POW (P < 0.05). The numbers of fibroblasts and vascular endothelial cells in E group were smaller than those in C group. CONCLUSION: Application of dermal template overlain with thin split-thickness autograft to wounds could induce P53 expression and cell apoptosis, thereby reduce scar formation, resulting in improvement of the quality of wound healing.