Intracellular processing of epidermal growth factor by early wound healing cells

Epidermal growth factor (EGF) is a potent 53-amino-acid residue polypeptide that has been implicated in normal wound healing. Although past studies have shown that locally applied EGF accelerates wound healing, these studies have not examined intracellular events related to the processing of the growth factor. The objective of this study was to characterize both initial and later postbinding intracellular processing of EGF by a responsive cell line (osteoblasts) that is important in the healing of wounds. Cloned mouse calvarial osteoblasts (MC-3TC-E1) were incubated with radiolabeled EGF, with and without preincubation with nonlabeled EGF, for specific time intervals. Cell-associated radioactivity was characterized by nondenaturing polyacrylamide gel electrophoresis. Results showed that EGF is processed as three distinct species and that the relative proportions of these species are altered at later time periods when compared with initial processing. The patterns, similar to those reported for human fibroblasts, indicate a possible common pathway for the mitogenic signal in cells associated with the early events of wound healing. In addition, these data represent the first direct evidence that preexposure of cells to nonlabeled EGF alters the processing of radiolabeled EGF. This is significant, because cells must be exposed to EGF for 5 to 8 hours to elicit a growth response. Such data may help to explain the "lag phase" of wound healing.     

Assessment of burn depth and burn wound healing potential

The depth of a burn wound and/or its healing potential are the most important determinants of the therapeutic management and of the residual morbidity or scarring. Traditionally, burn surgeons divide burns into superficial which heal by rapid re-epithelialization with minimal scarring and deep burns requiring surgical therapy. Clinical assessment remains the most frequent technique to measure the depth of a burn wound although this has been shown to be accurate in only 60-75% of the cases, even when carried out by an experienced burn surgeon. In this article we review all current modalities useful to provide an objective assessment of the burn wound depth, from simple clinical evaluation to biopsy and histology and to various perfusion measurement techniques such as thermography, vital dyes, video angiography, video microscopy, and laser Doppler techniques. The different needs according to the different diagnostic situations are considered. It is concluded that for the initial emergency assessment, the use of telemetry and simple burn photographs are the best option, that for research purposes a wide range of different techniques can be used but that, most importantly, for the actual treatment decisions, laser Doppler imaging is the only technique that has been shown to accurately predict wound outcome with a large weight of evidence. Moreover this technique has been approved for burn depth assessment by regulatory bodies including the FDA.     

基因重组碱性成纤维细胞生长因子促进猪深Ⅱ度烧伤创面愈合的实验研究

将基因重组的碱性成纤维细胞生长因子（ｂＦＧＦ）作为外源性生长因子来观察比较不同浓度的ｂＦＧＦ对猪深Ⅱ度烧伤创面愈合的影响。结果表明连续用药３～５天后，创面外观及电脑图像分析显示，ｂＦＧＦ对猪深Ⅱ度烧伤创面的愈合有一剂量效应。创面活检标本经用流式细胞计数仪做细胞ＤＮＡ的周期分析表明，用ｂＦＧＦ后创面细胞的Ｇ１期比例下降，Ｓ期和Ｇ２＋Ｍ期比例增多；其变化规律与创面所用的ｂＦＧＦ浓度有关，并与电脑图像分析所得的数据相一致。提示浓度合适的ｂＦＧＦ能明显地促进创面的愈合。     

基因重组碱性成纤维细胞生长因子促进猪深Ⅱ度烧伤创面愈合的实验研究

将基因重组的碱性成纤维细胞生长因子(bFGF)作为外源性生长因子来观察比较不同浓度的 bFGF 对猪深Ⅱ度烧伤创面愈合的影响。结果表明连续用药3～5天后,创面外观及电脑图像分析显示,bFGF 对猪深Ⅱ度烧伤创面的愈合有一剂量效应。创面活检标本经用流式细胞计数仪做细胞 DNA的周期分析表明,用 bFGF 后创面细胞的 G_1期比例下降,S 期和 G_2 M 期比例增多;其变化规律与创面所用的 bFGF 浓度有关,并与电脑图像分析所得的数据相一致。提示浓度合适的 bFGF 能明显地促进创面的愈合。     

Deep partial thickness burn blister fluid promotes neovascularization in the early stage of burn wound healing

The effect of burn blister fluid in neovascularization during burn wound healing is unknown. Burn blister fluid, containing a large amount of chemokines, is thought to play a role in the early stage of neovascularization. This process includes angiogenesis and vasculogenesis. Because of different healing time of burn wounds, we hypothesized that neovascularization in superficial partial thickness burn (SPTB) and deep partial thickness burn (DPTB) wounds were different. The neovasculogenic effects of two different burn blister fluids were also different. We found Day 7 DPTB wounds had a significant increase in blood vessels compared with SPTB wounds by immunohistochemistry. DPTB blister fluid significantly promoted neovascularization via increasing endothelial cell proliferation, and migration and differentiation of circulating angiogenic cells relative to SPTB blister fluids. In the animal study, DPTB blister fluids markedly promoted new blood vessel formation compared with those from SPTB blister fluids using in vivo Matrigel plug assay. These results suggest that DPTB wounds require more new vessel formation than SPTB. Furthermore, the measurement of angiogenic activities in burn blister fluids serves as a possible tool for assessing burn wound status.     

烧伤创面愈合的信号转导机制

After 50 years of development in science of bums care in China, we have basically solved coverage of deep wounds of burn trauma, as well as role of multiple growth factors and stem cell in wound healing, making great contribution to improving the treatment of patients with large area of deep bums. Surgeons are paying close attention to problems of wound healing, especially in the fields of starless healing and rehabilitation. To solve these problems, we need to do further investigation on multiple growth factors as well as proliferation/differentiation of stem cells in regulation of cell growth and differentiation in wound healing. Therefore ,we are facing a even more serious challenge.     

细胞免疫与烧伤创面愈合的实验研究

为探讨免疫低下对烧伤创面愈合的影响,设计了用低剂量钴源照射的方法建立的免疫抑制模型,并在该模型的基础上观察了免疫抑制大鼠Ⅱ度烧伤创面愈合的情况。结果表明:①大鼠接受2Gy~(60)Co 照射后20天内,Th/Ts 比值和 T 细胞肿瘤花环率持续下降。照射后皮肤组织 DNA 含量及细胞周期均无明显改变。②免疫抑制大鼠胶原修复能力下降,创面愈合百分率低于正常大鼠。由此证实了免疫功能低下对创面愈合的抑制作用。     

细胞免疫与烧伤创面愈合的实验研究

为探讨免疫低下对烧伤创面愈合的影响，设计了用低剂量钴源照射的方法建立的免疫抑制模型，并在该模型的基础上观察了免疫抑制大鼠Ⅱ度烧伤创面愈合的情况。结果表明：①大鼠接受２Ｇｙ６０Ｃｏ照射后２０天内，Ｔｈ／Ｔｓ比值和Ｔ细胞肿瘤花环率持续下降。照射后皮肤组织ＤＮＡ含量及细胞周期均无明显改变。②免疫抑制大鼠胶原修复能力下降，创面愈合百分率低于正常大鼠。由此证实了免疫功能低下对创面愈合的抑制作用。     

积极开展烧伤创面愈合研究

创面愈合问题对于烧伤来说主要是及早、永久性覆盖创面和防治瘢痕过度增生。创面愈合的基础研究进展很快 ,从细胞因子、细胞间粘附分子、细胞内信号传导到基因组学、蛋白质组学方法筛选愈合相关基因和功能蛋白。但临床应用性研究仍局限于细胞生长因子 ,且药物剂型、给药途径及经济疗效学部分限制了临床探索性应用。而创面覆盖物的研究由于近年来人工真皮、脱细胞真皮基质 (ａｃｅｌｌｕｌａｒｄｅｒｍｉｓｍａｔｒｉｘ ,ＡＤＭ )、复合皮乃至组织工程化皮肤的大量研发又趋热门。有关创面愈合后的瘢痕过度增生 ,近年来研究热点转向瘢痕相关基…     

Stem cells in burn wound healing: A systematic review of the literature

IntroductionSevere burns are often associated with high morbidity and unsatisfactory functional and esthetic outcomes. Over the last two decades, stem cells have generated great hopes for the treatment of numerous conditions including burns. The aim of this systematic review is to evaluate the role of stem cell therapy as a means to promote burn wound healing.MethodsComprehensive searches in major databases were carried out in March 2017 for articles on stem cell therapy in burn wound healing. In total 2103 articles were identified and screened on the basis of pre-determined inclusion and exclusion criteria.ResultsFifteen experimental and two clinical studies were included in the review. The majority of studies reported significant improvement in macroscopic burn wound appearance as well as a trend toward improved microscopic appearance, after stem cell therapy. Other parameters evaluated, such as re-vascularization, collagen formation, level of pro- and anti-inflammatory mediators, apoptosis and cellular infiltrates, yielded heterogeneous results across studies.ConclusionStem cell therapy appears to exert a positive effect in burn wound healing. There is, therefore, justification for continued efforts to evaluate the use of stem cells as an adjunct to first-line therapies in burns.     

Rapamycin reduces burn wound progression by enhancing autophagy in deep second‐degree burn in rats

Burn wound progression is caused by many mechanisms including local tissue hypoperfusion, prolonged inflammation, free radical damage, apoptosis, and necrosis in burn wounds. Autophagy, a homeostatic process by which cells break down their own components, was found to protect against ischemic injury, inflammatory diseases, and apoptosis in some cases. We tested whether rapamycin, an autophagy inducer, could ameliorate burn wound progression and promote wound healing through autophagy enhancement. Using a previously described deep second‐degree burn model, we first tested the effects of rapamycin on autophagic response in burn wound tissue. Autophagy levels in wound tissue of treated rats were increased as compared with controls. Furthermore, we found that laser Doppler flowmetry values and Na/K‐ATPase activities were markedly higher in the treated wounds. The content of interleukin‐8, methane dicarboxylic aldehyde, and myeloperoxidase activity in the wounds of treated rats were much lower than in controls. The apoptotic rates in treated wounds were much lower than controls as determined by terminal deoxynucleotidyl transferase mediated nick end labeling assay. Finally, histomorphological analysis showed that burn wound progression in the treatment group was ameliorated. The time to wound reepithelialization was shorter in the treated wounds than controls 22.5 ± 1.4 days vs. 24.8 ± 1.3 days (mean ± standard deviation, p < 0.01).     

细胞免疫与烧伤创面愈合的实验研究

为探讨免疫低下对烧伤创面愈合的影响，设计了用低剂量钴源照射的方法建立的免疫抑制模型，并在该模型的基础上观察了免疫抑制大鼠Ⅱ度烧伤创面的情况，结果表明：（１）大鼠接受２Ｇｙ＾６０Ｃｏ照射后２０天内，Ｔｈ／Ｔｓ比值和Ｔ细胞肿瘤花环率持续下降，照射皮肤组织ＤＮＡ含量及细胞周期均无明显改变；（２）免疫抑制大鼠胶原修复能力下降，创面愈合百分率低下正常大鼠，由此证实了免疫功能低下对创面愈合的抑制作用。     

Validity of thermography for measuring burn wound healing potential

Accurate assessment of burn wound depth and the associated healing potential is vital in determining the need for surgical treatment in burns. Infrared thermography measures the temperature of the burn wound noninvasively, thereby providing indirect information on its blood flow. Previous research demonstrated that a small, low‐priced, handheld thermal imager has an excellent reliability, but a moderate validity for measuring burn wound healing potential. A new and more sensitive version of this convenient device has become available. The aim of this study was to evaluate the validity of thermography for measuring burn wound healing potential, compared to Laser Doppler Imaging (LDI) as a reference standard. Thermal images and LDI scans were obtained from burn wounds between 2 and 5 days postburn. Temperature differences between burned and nonburned skin (ΔT) were calculated. To evaluate validity, ΔT values were compared to the healing potential categories assessed by LDI. Two receiver operating characteristic curves were created and two ΔT cutoff values were calculated to illustrate the ability to discriminate between burn wounds that heal in a time period of less than 14 days, between 14 and 21 days, and more than 21 days. Between June and October 2018, 43 burn wounds in 32 patients were measured. ΔT cutoff values of 0.6°C (sensitivity 68%, specificity 95%) and ?2.3°C (sensitivity 30%, specificity 95%) were calculated to discriminate between burn wounds that heal in <14 and ≥14 days, and burn wound that heal in ≤21 and >21 days, respectively. This study shows a good validity of the feasible thermal imager for the assessment of burn wound healing potential. Therefore, we consider it a promising technique to be used for triage in local hospitals and general practices, and as a valuable addition to clinical evaluation in burn centers.     

Topical oxygen and burn wound healing: a review

Oxygen is essential for the epithelialization and contraction of the burn wound as well as for the collagen maturation and synthesis. Inspiration of pure oxygen or employing hyperbaric oxygen might delay wound healing due to an intensive vasoconstriction. The accumulated data suggest a beneficial effect of topical oxygen on the wound healing process of burns.     

更进一步提高深度烧伤创面修复质量

This article summarizes methods of repair of massive and deep wounds, elucidates how to improve wound healing quality and avoid scar deformity after deep hum. A part of denatured dermis (non-necrotic)in deep partial-thickness burn, "mixed degree" burn, even in full-thickness burn wounds before forming eschar can be preserved and covered with autolo-gous skin, thereby to avoid secondary damage to the structure of subcutaneous tissue and the junction of dermis-adipose, thus to result in good functions, appearance, and survival rate. After skin grafting, wound healing quality and appearance are im-proved, joint function and elasticity of skin are enhanced, the degree of scar contracture is relieved due to preservation of nor-mal adipose tissue after escharectomy. The study of composite artifical skin will be actively developed in the future. Tissue-en-gineering skin and stem cells can be successfully used in pa-tients with deep burns for starless healing with restoration of physiological functions in a short period.     

Effect of hyperbaric oxygen on second-degree burn wound healing

We present a controlled study that indicates faster epithelialization of blister-removed second-degree burn wounds in guinea pigs treated with hyperbaric oxygen (HBO). Assessment of vascularity by india ink perfusion indicated earlier return of capillary patency in the HBO-treated group. An examination of the question of a comparative increase in DNA synthetic activity in the HBO-treated animals showed a slightly higher absolute ratio of labeled to unlabeled cells, but the difference was not statistically significant. It is likely that the mechanisms whereby HBO influenced the above events were mediated not only by increased oxygen delivery, but by increased atmospheric pressure on the wound.     

Bioactive peptide amphiphile nanofiber gels enhance burn wound healing

BackgroundBurns are physically debilitating and potentially fatal injuries. The standard-of-care for burn wounds is the coverage with gauze dressings designed to minimize trauma to the regenerating epidermis and dermis during dressing changes. However, deep partial- and full-thickness burns always heal slowly when standard wound care alone is performed. We have previously reported that peptide amphiphile (PA) gels, pH-induced self-assembling nanostructured fibrous scaffolds, promote cell proliferation and have great potential in regenerative medicine for rapid repair of tissues. In this study, we hypothesized that the PA gels are capable of accelerating wound healing in burn injury.MethodsArtificially generated thermally damaged fibroblasts and human umbilical vein endothelial cells were seeded onto the various PA nanofiber gels including bioactive and nonbioactive peptide sequences. Cell proliferation was assessed at different time points, and thermally damaged fibroblasts and HUVECs manifested increased proliferation with time when cultured with various PA gels. To determine in vivo effects, burn wounds of rats were treated with the bioactive Arg-Gly-Asp-Ser (RGDS)-modified gel that showed greater cell proliferation in vitro. The wound closure was observed, and skin samples were harvested for histologic evaluation.ResultsCell proliferation using the RGDS-PA gel was significantly higher than that observed in other gels. The RGDS-PA gel significantly enhanced re-epithelialization during the burn wound healing process between days 7 and 28. Application of PA gels accelerates the recovery of deep partial-thickness burn wounds by stimulation of fibroblasts and the creation of an environment conducive to epithelial cell proliferation and wound closure.ConclusionsThis biomaterial represents a new therapeutic strategy to overcome current clinical challenges in the treatment of injuries resulting from burns.