正常与糖尿病小鼠脂肪间充质干细胞移植促进皮肤创伤愈合的比较

目的比较正常和糖尿病小鼠脂肪间充质干细胞(Adipose mesenchymal stem cells,ADSCs)移植促进皮肤创伤愈合疗效差别。方法无菌条件下获取正常小鼠及糖尿病小鼠的ADSCs,应用流式细胞术对3代细胞表面抗原CD34、CD45、CD90、CD105进行表型鉴定。应用WST法和Transwell迁移实验检测细胞增殖和迁移情况。应用ELISA对正常小鼠及糖尿病小鼠的ADSCs条件培养液中VEGF、HGF和IGF-1蛋白含量进行检测。建立小鼠皮肤创伤模型并随机分为3组,分别以皮内注射方式将3代正常小鼠或糖尿病小鼠来源ADSCs的细胞混悬液移植到小鼠创面四周,空白对照组注射生理盐水,于伤后14d观察创面愈合情况;Western blot检测伤后14d创面组织Bcl-2蛋白表达。结果小鼠ADSCs表达CD90和CD105,不表达CD34和CD45,与正常小鼠相比,糖尿病小鼠来源的ADSCs增殖和迁移能力下降,条件培养液中VEGF、HGF和IGF-1蛋白含量明显降低。糖尿病小鼠ADSCs移植组于创伤后第14d伤口愈合率为(79.6%±6.2%),均显著低于正常小鼠移植组14d的(97.1%±4.1%),两者均高于对照组14d的(64.6%±2.9%,0.05)。与正常小鼠移植组相比,糖尿病小鼠移植组伤后14d创面组织Bcl-2表达水平降低,高于对照组创面组织Bcl-2表达水平。结论正常小鼠来源ADSCs较糖尿病小鼠ADSCs更能促进小鼠皮肤创面愈合。     

Shear stress and VEGF enhance endothelial differentiation of human adipose-derived stem cells

Abstract

Herein we combine chemical and mechanical stimulation to investigate the effects of vascular endothelial growth factor (VEGF) and physiological shear stress in promoting the differentiation human adipose derived stem cells (ADSCs) into endothelial cells. ADSCs were isolated and characterized; endothelial differentiation was promoted by culturing confluent cells in 50?ng/ml VEGF under physiological shear stress for up to 14 days. Afterwards, endothelial cells were seeded onto collagen or acellular aortic valve matrices and exposed to four culture conditions: shear stress + VEGF; shear stress ? VEGF; static + VEGF and static ? VEGF. After 7 days, phenotype was investigated. ADSCs subjected to shear stress and VEGF express a comprehensive range of specific endothelial markers (vWF, eNOS and FLT-1 after 7 days and CD31, FLk-1 and VE-cadherin after 14 days) and maintain the phenotype when seeded onto scaffolds. Our protocol proved to be an efficient source of endothelial-like cells for tissue engineering based on autologous ADSC.     

人脂肪干细胞与VEGF-PLGA纳米微球缓释系统构建工程化脂肪组织的相关研究

目的 探讨缓释血管内皮生长因子复合支架与脂肪干细胞构建工程化脂肪的可行性。方法 制备VEGF-PLGA纳米微球缓释支架,检测支架释放 VEGF 浓度,体外提取培养 ADSCs,检测复合支架对 ASC 生长增殖的影响。将复合支架和ADSCs植入裸小鼠背部,8 周后切取植入物称重,组织切片HE染色,评估效果。结果 VEGF-PLGA纳米微球缓释复合支架能连续 12 d释放较高浓度的VEGF,对 ADSCs的生长增殖无影响。动物实验结果显示复合支架与ADSCs共移植能显著提高脂肪组织的形成,增加血管的生成（P＜0.01）,减少组织坏死。结论 VEGF-PLGA纳米微球缓释系统具有良好的生物安全性,其与ADSCs共移植构建工程化脂肪组织具有一定的可行性。     

Vascular endothelial growth factor-C accelerates diabetic wound healing

Diabetes impairs numerous aspects of tissue repair. Failure of wound angiogenesis is known to delay diabetic wound healing, whereas the importance of lymphangiogenesis for wound healing is unclear. We have examined whether overexpression of vascular endothelial growth factor (VEGF)-C via an adenoviral vector could improve the healing of full-thickness punch biopsy wounds in genetically diabetic (db/db) mice. We found that VEGF-C enhanced angiogenesis and lymphangiogenesis in the wound and significantly accelerated wound healing in comparison to the control wounds. VEGF-C also recruited inflammatory cells, some of which expressed VEGFR-3. On the other hand, when the function of endogenous VEGF-C/VEGF-D was blocked with a specific inhibitor, wound closure was delayed even further. These results suggest a function for VEGF-C in wound healing and demonstrate the therapeutic potential of VEGF-C in the treatment of diabetic wounds.     

低能量体外震波对糖尿病慢性创面模型血管新生和血管内皮细胞生长因子表达的影响**☆

背景：体外震波作为一种非侵入性的物理刺激近年来发现具有促进新生血管形成、促进组织修复的功能。 目的：观察体外震波对创面内血管内皮细胞生长因子表达和新血管形成的影响及促进创面愈合的作用。 方法：72只SD大鼠随机均分为治疗组、糖尿病组及对照组。治疗组和糖尿病组制作糖尿病慢性创面模型。建模后1 d治疗组创面用体外震波处理,糖尿病组和对照组仅涂抹耦合液。观察创面的肉芽组织和新血管形成情况,检测血管内皮细胞生长因子蛋白含量及mRNA的表达水平。 结果与结论：与糖尿病组比较,治疗组创面的闭合率增加。治疗后3 d开始,治疗组创面内毛细血管数量比糖尿病组增多,肉芽组织相应增加。与对照组比较,糖尿病组血管内皮细胞生长因子蛋白含量和mRNA表达水平在3 d和7 d均降低,在7 d出现下降。经体外震波治疗后,各时间段表达均增高,在14 d出现下降。说明糖尿病创面局部血管内皮细胞生长因子分泌量降低和高表达时段缩短是其难愈的重要因素之一,体外震波治疗可增加糖尿病创面组织内血管内皮细胞生长因子的表达强度,延长其高表达的时间,从而促进创面内新血管形成,最终加快肉芽组织生长和创面愈合。关键词：体外震波;糖尿病创面;血管内皮细胞生长因子;血管新生;愈合 缩略语注释：VEGF: vascular endothelial growth factor,血管内皮细胞生长因子 doi:10.3969/j.issn.1673-8225.2012.15.019     

Combined effects of artificial dermis and vascular endothelial growth factor concentration gradient on wound healing in diabetic porcine model

Wounds in patients with diabetes mellitus are one of the most prevalent impaired wounds in the world. Vascular endothelial growth factor (VEGF) is one of the most important proangiogenic mediators. Artificial dermal (AD) such as Pelnac^® has been shown, in humans and animal models, a great therapeutic potential in full-thickness skin wounds. We attempt to promote the wound healing in diabetic porcine models through combined use of AD and constant concentration of VEGF or VEGF concentration gradient. We created full-thickness excisional wounds in diabetic animal models. Analyzed the healing process through images, histology and immunohistochemistry. Results show that the combination of AD and concentration gradient of VEGF could provide an appropriate angiogenesis, improve granulation formation, increase epithelization and maintain the VEGF levels of the wound bed. Eventually accelerate the direct healing of diabetic wounds or make good preparation for secondary skin graft.     

Expressional regulation of angiopoietin-1 and -2 and the tie-1 and -2 receptor tyrosine kinases during cutaneous wound healing: a comparative study of normal and impaired repair

It has become evident that a closely regulated presence of vascular endothelial growth factor (VEGF) and angiopoietin (Ang) factors determines the fate of blood vessel formation during angiogenesis. As angiogenesis is central to a normal wound-healing process, we investigated the regulation of Ang-1 and -2 and the related tyrosine kinase with immunoglobulin and epidermal growth factor homology (Tie)-1 and -2 receptors during normal repair in Balb/c mice and diabetes-impaired wound healing conditions in genetically diabetic (db/db) mice. For both normal and impaired healing conditions, we observed a constitutive expression of Ang-1, which was paralleled by an increase of Ang-2 upon injury. Whereas the observed Ang-2 expression declines from Day 7 after injury in control mice, diabetic-impaired healing was characterized by still increasing amounts of Ang-2 at these time points. Furthermore, Tie-1 was strongly induced during repair with a prolonged expression in diabetic mice, whereas Tie-2 expression was constitutive during normal repair but completely absent in diabetes-impaired healing. The overexpression of Ang-2 in the presence of markedly reduced VEGF in wounds of diabetic mice was associated with a dramatic decrease in endothelial cell numbers compared with normal healing as assessed by analysis of the endothelium-specific markers CD31 and von Willebrand factor, whereas the lymphatic endothelium remained stable as determined by expression of VEGF receptor-3 (VEGFR-3/Flt-4).     

Mesenchymal stem cells enhance wound healing through differentiation and angiogenesis

Although chronic wounds are common, treatment for these disabling conditions remains limited and largely ineffective. In this study, we examined the benefit of bone marrow-derived mesenchymal stem cells (BM-MSCs) in wound healing. Using an excisional wound splinting model, we showed that injection around the wound and application to the wound bed of green fluorescence protein (GFP)(+) allogeneic BM-MSCs significantly enhanced wound healing in normal and diabetic mice compared with that of allogeneic neonatal dermal fibroblasts or vehicle control medium. Fluorescence-activated cell sorting analysis of cells derived from the wound for GFP-expressing BM-MSCs indicated engraftments of 27% at 7 days, 7.6% at 14 days, and 2.5% at 28 days of total BM-MSCs administered. BM-MSC-treated wounds exhibited significantly accelerated wound closure, with increased re-epithelialization, cellularity, and angiogenesis. Notably, BM-MSCs, but not CD34(+) bone marrow cells in the wound, expressed the keratinocyte-specific protein keratin and formed glandular structures, suggesting a direct contribution of BM-MSCs to cutaneous regeneration. Moreover, BM-MSC-conditioned medium promoted endothelial cell tube formation. Real-time polymerase chain reaction and Western blot analysis revealed high levels of vascular endothelial growth factor and angiopoietin-1 in BM-MSCs and significantly greater amounts of the proteins in BM-MSC-treated wounds. Thus, our data suggest that BM-MSCs promote wound healing through differentiation and release of proangiogenic factors. Disclosure of potential conflicts of interest is found at the end of this article.     

Antiangiogenic properties of silver nanoparticles

Angiogenesis is an important phenomenon involved in normal growth and wound healing processes. An imbalance of the growth factors involved in this process, however, causes the acceleration of several diseases including malignant, ocular, and inflammatory diseases. Inhibiting angiogenesis through interfering in its pathway is a promising methodology to hinder the progression of these diseases. The function and mechanism of silver nanoparticles (Ag-NPs) in angiogenesis have not been elucidated to date. PEDF is suggested to be a potent anti-angiogenic agent. In this study, we postulated that Ag-NPs might have the ability to inhibit angiogenesis, the pivotal step in tumor growth, invasiveness, and metastasis. We have demonstrated that Ag-NPs could also inhibit vascular endothelial growth factor (VEGF) induced cell proliferation, migration, and capillary-like tube formation of bovine retinal endothelial cells like PEDF. In addition, Ag-NPs effectively inhibited the formation of new blood microvessels induced by VEGF in the mouse Matrigel plug assay. To understand the underlying mechanism of Ag-NPs on the inhibitory effect of angiogenesis, we showed that Ag-NPs could inhibit the activation of PI3K/Akt. Together, our results indicate that Ag-NPs can act as an anti-angiogenic molecule by targeting the activation of PI3K/Akt signaling pathways.     

Neuropilin-1 Participates in Wound Angiogenesis

Angiogenesis, the formation of new capillaries from existing vasculature, plays an essential role in tissue repair. The rapid onset and predominance of proangiogenic factors optimizes healing in damaged tissues. One factor that directly mediates wound vessel angiogenesis is vascular endothelial growth factor (VEGF). Although much is known about the biology of VEGF and its cognate receptors, VEGFR1 and VEGFR2, the role of a recently identified co-receptor for VEGF, neuropilin-1, is not well understood. Using a murine model of dermal wound repair, we found that neuropilin-1 was abundantly expressed on new vasculature in healing wounds. Moreover, mice treated with anti-neuropilin-1 antibodies exhibited a significant decrease in vascular density within these wounds (67% decrease, P = 0.0132). In in vitro assays, VEGF induced formation of endothelial cord-like structures on collagen gel and endothelial cell migration toward VEGF was inhibited by antibodies directed against neuropilin-1. These results provide both in vitro and in vivo evidence for a critical role of neuropilin-1 in wound angiogenesis.     

血清IGF-1和VEGF水平与糖尿病足关系的研究

目的研究糖尿病足患者血清IGF-1和VEGF水平与糖尿病足部溃疡或坏疽的关系。方法分别采用放射免疫分析法和定量双抗体夹心ELISA法检测23例糖尿病足患者血清IGF-1和VEGF水平,并与健康人和2型糖尿病患者进行比较。结果糖尿病足患者血清IGF-1和VEGF水平显著低于糖尿病患者和健康对照组(P<0.05)。结论生长因子IGF-1和VEGF是糖尿病足发生和发展的重要影响因素,IGF-1和VEGF水平低下可能是糖尿病足部溃疡经久不愈的重要原因。     

Synergistic angiogenesis promoting effects of extracellular matrix scaffolds and adipose-derived stem cells during wound repair

Slow vascularization rate is considered one of the main drawbacks of scaffolds used in wound healing. Several efforts, including cellular and acellular technologies, have been made to induce vascular growth in scaffolds. However, thus far, there is no established technology for inducing vascular growth. The aim of this study was to promote the vascularization capacities of scaffolds by seeding adipose-derived stem cells (ADSCs) on them and to compare the vascularization capacities of different scaffolds seeded with ADSCs. Two kinds of extracellular matrix scaffolds (small intestinal submucosa [SIS] and acellular dermal matrix [ADM]) and a kind of composite scaffold (collagen-chondroitin sulfate-hyaluronic acid [Co-CS-HA]) were selected. Subcutaneous implantation analysis showed that the vascularization capacity of SIS and ADM was greater than that of Co-CS-HA. ADSCs seeded in SIS and ADM secreted greater amounts of vascular endothelial growth factor than those seeded in Co-CS-HA. In a murine skin injury model, ADSC-seeded scaffolds enhanced the angiogenesis and wound healing rate compared with the nonseeded scaffolds. Moreover, ADSC-SIS and ADSC-ADM had greater vascularization capacity than that of ADSC-Co-CS-HA. Taken together, these results suggest that ADSCs could be used as a cell source to promote the vascularization capacities of scaffolds. The vascularization capacities of ADSC-seeded scaffolds were influenced by both the vascularization capacities of the scaffolds themselves and their effects on the angiogenic potential of ADSCs; the combination of extracellular matrix scaffolds and ADSCs exhibited synergistic angiogenesis promoting effects.     

晚期糖基化终产物对人脂肪间充质干细胞功能影响的体外研究*

 目的：探讨晚期糖基化终产物（AGEs）对人脂肪来源的间充质干细胞（hADSCs）促进创伤修复功能的影响。方法：体外培养hADSCs,实验分为牛血清白蛋白（BSA）对照组、低浓度糖基化修饰的牛血清白蛋白（AGE-BSA）效应组和高浓度AGE-BSA效应组。采用WST法和Transwell迁移实验检测各组细胞增殖和迁移情况。应用实时定量PCR和ELISA检测各组细胞分泌血管内皮生长因子（VEGF）、肝细胞生长因子（HGF）和胰岛素样生长因子1（IGF-1）的表达。结果：与对照组相比, AGE-BSA组增殖能力和迁移能力明显下降（P<0.05）,VEGF、HGF和IGF-1 mRNA及蛋白表达水平显著降低（P<0.05）。结论：AGEs能损伤hADSCs的促进创伤修复功能,因而能够影响hADSCs治疗糖尿病皮肤溃疡病的治疗效果。     

Nicotine accelerates angiogenesis and wound healing in genetically diabetic mice

Recently, we have discovered an endogenous cholinergic pathway for angiogenesis mediated by endothelial nicotinic acetylcholine receptors (nAChRs). Since angiogenesis plays a major role in wound repair, we hypothesized that activation of nAChRs with nicotine would accelerate wound healing in a murine excisional wound model. In genetically diabetic and control mice full-thickness skin wounds (0.8 cm) were created on the dorsum and topically treated over 7 days with either vehicle (phosphate-buffered saline, PBS) or nicotine (10(-8) mol/L, 10(-9) mol/L; each, n = 5). Wound size was measured over 14 days followed by resection, histological analysis, and quantitation of vascularity. In diabetic animals an agonist (epibatidine, 10(-10) mol/L) or antagonist (hexamethonium, 10(-4) mol/L) of nAChRs as well as the positive control basic fibroblast growth factor (bFGF, 25 microg/kg) were also tested. To further study the role of endothelial nAChRs in angiogenesis, we used an ex vivo vascular explant model. In diabetic mice wound healing was markedly impaired. Nicotine significantly accelerated wound healing as assessed by closure rate and histological score. The effects of nicotine were equal to bFGF and were mimicked by epibatidine and blocked by hexamethonium. Histomorphometry revealed increased neovascularization in animals treated with nicotine. Furthermore, capillary-like sprouting from vascular explants was significantly enhanced by nicotine. In conclusion, agonist-induced stimulation of nAChRs accelerates wound healing in diabetic mice by promoting angiogenesis. We have discovered a cholinergic pathway for angiogenesis that is involved in wound healing, and which is a potential target for therapeutic angiogenesis.     

Dual growth factor releasing multi-functional nanofibers for wound healing

The objective of this research is to develop a dual growth factor-releasing nanoparticle-in-nanofiber system for wound healing applications. In order to mimic and promote the natural healing procedure, chitosan and poly(ethylene oxide) were electrospun into nanofibrous meshes as mimics of extracellular matrix. Vascular endothelial growth factor (VEGF) was loaded within nanofibers to promote angiogenesis in the short term. In addition, platelet-derived growth factor-BB (PDGF-BB) encapsulated poly(lactic-co-glycolic acid) nanoparticles were embedded inside nanofibers to generate a sustained release of PDGF-BB for accelerated tissue regeneration and remodeling. In vitro studies revealed that our nanofibrous composites delivered VEGF quickly and PDGF-BB in a relayed manner, supported fibroblast growth and exhibited anti-bacterial activities. A preliminary in vivo study performed on normal full thickness rat skin wound models demonstrated that nanofiber/nanoparticle scaffolds significantly accelerated the wound healing process by promoting angiogenesis, increasing re-epithelialization and controlling granulation tissue formation. For later stages of healing, evidence also showed quicker collagen deposition and earlier remodeling of the injured site to achieve a faster full regeneration of skin compared to the commercial Hydrofera Blue® wound dressing. These results suggest that our nanoparticle-in-nanofiber system could provide a promising treatment for normal and chronic wound healing.     

Plasmin modulates vascular endothelial growth factor-A-mediated angiogenesis during wound repair

Plasmin-catalyzed cleavage of the vascular endothelial growth factor (VEGF)-A isoform VEGF165 results in loss of its carboxyl-terminal heparin-binding domain and significant loss in its bioactivity. Little is known about the in vivo significance of this process. To investigate the biological relevance of the protease sensitivity of VEGF165 in wound healing we assessed the activity of a VEGF165 mutant resistant to plasmin proteolysis (VEGF165(A111P)) in a genetic mouse model of impaired wound healing (db/db mouse). In the present study we demonstrate that in this mouse model plasmin activity is increased at the wound site. The stability of the mutant VEGF165 was substantially increased in wound tissue lysates in comparison to wild-type VEGF165, thus indicating a prolonged activity of the plasmin-resistant VEGF165 mutant. The db/db delayed healing phenotype could be reversed by topical application of wild-type VEGF165 or VEGF165(A111P). However, resistance of VEGF165 to plasmin cleavage resulted in the increased stability of vascular structures during the late phase of healing due to increased recruitment of perivascular cells and delayed and reduced endothelial cell apoptosis. Our data provide the first indication that plasmin-catalyzed cleavage regulates VEGF165-mediated angiogenesis in vivo. Inactivation of the plasmin cleavage site Arg110/Ala111 may preserve the biological function of VEGF165 in therapeutic angiogenesis under conditions in which proteases are highly active, such as wound repair and inflammation.     

Hepatocyte growth factor increases expression of vascular endothelial growth factor and plasminogen activator inhibitor-1 in human keratinocytes and the vascular endothelial growth factor receptor flk-1 in human endothelial cells

The pleiotropic growth factor hepatocyte growth factor/scatter factor (HGF/SF) has been implicated by clinical and experimental studies in repair mechanisms in different organs and tissues. However, no data on the impact of HGF/SF in wound healing in the skin are yet available. Proliferating and migrating keratinocytes play a major role in repair processes in the skin by closing the wound. Recent evidence gathered from studies that used gene-deficient mice has implicated the plasminogen activator (PA)/plasmin system in wound healing, which depends on controlled matrix degradation and deposition during cell migration and proliferation. Furthermore, keratinocytes are an important source of vascular endothelial growth factor (VEGF), which is a potent inducer of angiogenesis. In this study, we show that in human keratinocytes HGF/SF but not the related cytokine macrophage stimulating protein (MSP) significantly increases expression of VEGF and plasminogen activator inhibitor-1 (PAI-1) on the level of protein and mRNA. Furthermore, we demonstrate that HGF/SF increases the expression of the VEGF receptor flk-1 in human endothelial cells and that, in an angiogenesis co-culture assay of endothelial cells and keratinocytes, HGF/SF increases endothelial cell tube formation significantly. Therefore, we propose a role for HGF/SF in wound repair in the skin: HGF/SF--produced by activated fibroblasts--increases in keratinocytes the expression of PAI-1, which leads to increased matrix stability during the repair process and which could also limit activation of HGF/SF by proteases such as urokinase-type PA (u-PA) or tissue-type PA (t-PA). Furthermore HGF/SF also increases the expression of VEGF in these cells, thereby initiating angiogenesis in a paracrine manner. This effect would be enhanced by an increased responsiveness of endothelial cells toward VEGF, resulting from the HGF/SF-induced up-regulation of flk-1 on these cells.     

Acceleration of diabetic wound healing by an angiopoietin peptide mimetic

Angiopathies are one of the leading underlying causes of morbidity in diabetic patients. Poorly managed blood glucose levels contribute to vascular defects that manifest themselves in numerous different clinical conditions, including diabetic retinopathy, nephropathy, peripheral artery disease, and compromised wound healing. The angiopoietin family (Angs 1-4) has been shown to play a critical role in the growth and maintenance of vasculature. Here we evaluate the efficacy of a new Ang-based peptidomimetic compound, Vasculotide, on diabetic-related wound healing. Stimulation of endothelial cells (ECs) with Vasculotide results in activation of the Ang receptor, Tie 2, and its associated signaling pathways. This activation promoted biological responses such as EC survival, migration, and matrix metalloproteinase 2 (MMP2) production. We show that Vasculotide alone and in combination with vascular endothelial growth factor (VEGF) results in the production of well-arborized vessels supported by myogenic cells. Using an excisional skin-wound model produced on the back of diabetic B6.Cg-m(+/+)Lepr(db)/J (db/db) mice, we found that Vasculotide-treated wounds presented with decreased wound closure times (p < 0.05) and dramatic increases in granulation tissue (p < 0.01). Although the potential of this novel proangiogenic compound in treating microvascular dysfunction is not strictly limited to topical administration, we provide mechanistic evidence as a proof of principle in support of its efficacious use in diabetic wound healing.     

神经生长因子在糖尿病足创面组织中表达相关性的研究进展

动物实验研究证实神经生长因子（NGF）促进创面组织血管生成、血管内皮细胞再生,促进缺血创面的愈合及糖尿病创面的愈合。通过NGF在糖尿病创面表达改变的研究,有助于NGF促进糖尿病创面愈合机制的探讨,为糖尿病足创面愈合提供新的理论依据。