水凝胶携带重组人促红细胞生成素对大鼠深Ⅱ度烫伤创面愈合的影响

目的:探讨水凝胶携带重组人促红细胞生成素(rHuEPO)对深Ⅱ度烫伤创面愈合的影响。方法:建立18只SD大鼠深Ⅱ度烫伤模型,随机分为三组,每组6只,分别给予PBS、水凝胶、水凝胶+rHuEPO治疗处理,分别于烫伤即刻、14天、21天测量创面面积,并计算创面愈合指数;治疗21天后取烫伤组织进行组织切片、HE染色和免疫组化检测,比较三组标本上皮化程度、肉芽组织生成和血管形成情况,并进行组织学评分;比较治疗21天后各组血管内皮生长因子(VEGF)的表达。结果:治疗21天,水凝胶+rHuEPO组组织学评分高于水凝胶组和PBS组,表现为较多的肉芽组织形成和血管生成(P<0.05),创面愈合指数大于PBS组和水凝胶组(P<0.05),VEGF表达量高于PBS组和水凝胶组(P<0.05)。结论:应用水凝胶携带rHuEPO治疗深Ⅱ度烫伤可以增加烫伤组织VEGF表达,促进血管生成、肉芽组织生长、内皮增生和迁移,从而促进烫伤愈合。     

Accelerated Skin Wound Healing in Plasminogen Activator Inhibitor-1-Deficient Mice

Components of the fibrinolytic system have been implicated in cell migratory events associated with tissue remodeling. Studies in plasminogen-deficient mice (PG(-/-)) indicated that skin wound healing is impaired, but is resolved with an additional fibrinogen deficiency. Plasminogen activator inhibitor-1 (PAI-1) expression by keratinocytes has been identified shortly after wound injury. PAI-1 expression could affect wound healing by regulating the fibrinolytic environment of the wounded area, as well as influencing events associated with cell attachment and detachment through interactions with matrix proteins. The present study directly assesses PAI-1 involvement in skin wound healing through analyses of a dermal biopsy punch model in PAI-1-deficient (PAI-1(-/-) mice. While the cellular events associated with the healing process are similar between wild-type (WT) and PAI-1(-/-) mice, the rate of wound closure is significantly accelerated in PAI-1(-/-) mice.     

CD19, a Response Regulator of B Lymphocytes,Regulates Wound Healing through Hyaluronan-Induced TLR4 Signaling

Immune cells are critical to the wound-healing process, through both cytokine and growth factor secretion. Although previous studies have revealed that B cells are present within wound tissue, little is known about the role of B cells in wound healing. To clarify this, we investigated cutaneous wound healing in mice either lacking or overexpressing CD19, a critical positive-response regulator of B cells. CD19 deficiency inhibited wound healing, infiltration of neutrophils and macrophages, and cytokine expression, including basic and acidic fibroblast growth factor, interleukin-6, platelet-derived growth factor, and transforming growth factor-β. By contrast, CD19 overexpression enhanced wound healing and cytokine expression. Hyaluronan (HA), an endogenous ligand for toll-like receptor (TLR)-4, stimulated B cells, which infiltrates into wounds to produce interleukin-6 and transforming growth factor-β through TLR4 in a CD19-dependent manner. CD19 expression regulated TLR4 signaling through p38 activation. HA accumulation was increased in injured skin tissue relative to normal skin, and exogenous application of HA promoted wound repair in wild-type but not CD19-deficient mice, suggesting that the beneficial effects of HA to the wound-healing process are CD19-dependent. Collectively, these results suggest that increased HA accumulation in injured skin induces cytokine production by stimulating B cells through TLR4 in a CD19-dependent manner. Thus, this study is the first to reveal a critical role of B cells and novel mechanisms in wound healing.Healing of cutaneous wounds is a complex biological event that results from the interplay of a large number of resident and infiltrating cell types, including leukocytes.¹ Accumulating evidence has revealed a critical role of leukocytes in wound healing. Infiltrating neutrophils form a first line of defense against local infections and are also a source of pro-inflammatory cytokines to activate fibroblasts and keratinocytes.² Macrophages also regulate wound healing by antimicrobial function, wound debridement, and production of various growth factors, such as platelet-derived growth factor (PDGF), transforming growth factor (TGF)-β, basic fibroblast growth factor (bFGF), heparin binding epidermal growth factor, and TGF-α.^3,4,5,6 These factors stimulate the synthesis of extracellular matrix by local fibroblasts, generate new blood vessels, promote the granulation tissue formation, and enhance re-epithelialization.^4,5 Furthermore, a series of experimental studies have indicated a significant role for T lymphocytes in wound healing as growth factor-producing cells as well as immunological effector cells.^1,7,8,9 Thus, immune cells have an integral function in wound healing beyond their role in inflammation and host defense, mainly through the secretion of signaling molecules, such as cytokines and growth factors.⁶However, little is known regarding a role of B cells in wound healing. Previous studies have revealed that B cells are present within wound tissue^9,10,11 and that B cell count is rapidly increased in the first 4 days after wounding, and thereafter reaches a plateau before falling as the wounds heal.¹¹ Furthermore, recent assessment of the role of B cells in the immune system has indicated that B cells are more than just the precursors of antibody (Ab)-secreting cells.¹² B cells have essential functions in regulating immune responses, including the production of various cytokines and growth factors, antigen presentation, regulation of T cell activation and differentiation, and regulation of lymphoid organization.¹² Therefore, the increased numbers of B cells within wound tissue may reflect a role for these cells that has hitherto been unrecognized.Both innate and adaptive immune responses contribute to host defense cooperatively. B cells play a principal role in adaptive immune response through B cell antigen receptor (BCR). BCR-induced signals are further modified by other cell surface molecules including CD19. CD19, a major positive response regulator, is a critical B cell-specific signal transduction molecule of the immunoglobulin superfamily expressed by early pre-B cells from the time of heavy chain rearrangement until plasma cell differentiation.¹³ B cells also primarily participate in innate immunity; indeed, B cells express toll-like receptors (TLRs) and respond to exogenous innate stimuli such as lipopolysaccharide (LPS), a major component of Gram-negative bacteria. CD19 also regulates LPS signaling: B cells from CD19-deficient (CD19^−/−) mice are hyporesponsive to most transmembrane signals, including BCR ligation and LPS, while B cells from CD19-transgenic (CD19Tg) mice that overexpress CD19 by ∼threefold are hyperresponsive to these signals.^14,15 Thus, CD19 regulates both adaptive and innate immune responses.In the current study, to clarify the roles of B cells in wound healing, we investigated the wound-healing model in CD19^−/− and CD19Tg mice. The results of this study indicate that CD19 controls cytokine and growth factor production by B cells mainly through TLR4 signaling, which was activated by an endogenous TLR4 ligand hyaluronan (HA) increased in the wounded skin, and thereby CD19 regulates the skin wound-healing process.     

Advances in the Modulation of Cutaneous Wound Healing and Scarring

Cutaneous wounds inevitably heal with scars, which can be disfiguring and compromise function. In general, the greater the insult, the worse the scarring, although genetic make up, regional variations and age can influence the final result. Excessive scarring manifests as hypertrophic and keloid scars. At the other end of the spectrum are poorly healing chronic wounds, such as foot ulcers in diabetic patients and pressure sores. Current therapies to minimize scarring and accelerate wound healing rely on the optimization of systemic conditions, early wound coverage and closure of lacerations, and surgical incisions with minimal trauma to the surrounding skin. The possible benefits of topical therapies have also been assessed. Further major improvements in wound healing and scarring require an understanding of the molecular basis of this process. Promising strategies for modulating healing include the local administration of platelet derived growth factor (PDGF)-BB to accelerate the healing of chronic ulcers, and increasing the relative ratio of transforming growth factor (TGF)beta-3 to TGFbeta-1 and TGFbeta-2 in order to minimize scarring.     

The Effect of Complement Depletion on Wound Healing

The role of the complement system in nonspecific inflammation was investigated by depleting guinea pigs of serum complement with cobra venom factor (CoF). The progress of wound healing was compared in decomplemented and control animals which received buffer and no CoF. When wound tissue sections were assessed at 12 hours after wounding, no morphologic differences were observed between experimental and control wounds. Quantitation of 24-hour wound exudates by a point volumetric method revealed a 50% reduction in infiltrating polymorphonuclear neutrophilic leukocytes (PMN) in the absence of complement. A smaller decrease in mononuclear leukocytes (MNL) was seen. Red cells occupied four times as much space in the experimental wounds at 24 hours. In 48-hour wounds, PMN were still 50% of controls, but were near control levels at 72 hours. Despite the decreased influx of PMN, wound debridement and subsequent fibrogenesis proceeded as in the controls. No differences were seen in fibroblast proliferation, connective tissue formation or capillary regeneration. These results suggest that the complement system is not a primary mediator of inflammation following a nonimmunologic stimulus.     

Interleukin-33 Signaling Controls the Development of Iron-Recycling Macrophages

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Inflammation in Healing: I. Time-Course and Mediation of Exudation in Wound Healing in the Rat

The time-course of increased vascular permeability in excised wounds in the skin of the rat was measured by injecting Evan''s blue i.v. at various times after wounding and extracting the dye which exuded into the injured tissues during various short intervals of time. A single peak of increased permeability occurred within the first hour after which exudation rapidly diminished to a low level which then persisted for at least 5 days after wounding.In animals with circulating colloidal carbon only venules in the edge and floor of wounds exhibited increased permeability during the phase of maximum exudation, after which leakage occurred only from capillaries in the advancing edge of the healing granulation tissue.In controlled experiments, using rats matched for weight, the exudation in the first 30 min. after wounding was partially suppressed by inhibitors of histamine and serotonin, but not by anti-inflammatory agents which inhibit the kinins and/or kallikrein.It is concluded that, in the absence of exogenous irritation, the inflammatory component of the process of healing after cutaneous wounding is evanescent, slight in magnitude, and mediated by histamine and serotonin.     

超快动态交联的可注射壳聚糖-透明质酸水凝胶及促创伤愈合研究

可注射动态水凝胶是近年研究的热点,而制备无催化剂体系的快速交联的可注射动态水凝胶是研究的难点之一。以甲基丙烯酰化壳聚糖(CHMA)和醛基化透明质酸(ALHA)为原料,利用CHMA分子上的氨基与ALHA分子上的醛基和羧基,分别形成可逆动态席夫碱键和静电相互作用,可快速制备一种水凝胶。通过动态流变分析仪表征其凝胶化速率、剪切变稀行为和自愈合特征,通过体外细胞三维培养实验评估其细胞相容性,并通过急性全层皮肤创伤修复实验对其创伤愈合速率进行评估。结果表明,只需5 s,CHMA和ALHA的混合溶液就能形成凝胶。此外,该凝胶具有剪切变稀和快速自愈合的可注射特征,当扫描频率从10^-1 s^-1增加至10² s^-1时,其复数黏度由0.4 kPa降低至8 Pa;当应变在1%~1000%之间交替变化时,储能模量与损耗模量的大小能够迅速切换,且模量没有显著性地降低。同时,体外细胞三维培养实验表明,该水凝胶还具有优异的细胞相容性(细胞存活率高于95%),并且在雄性ICR小鼠急性全层皮肤缺损模型实验中,水凝胶组的创伤愈合时间相比空白对照组缩短5～7 d,表现出较快的创伤愈合速率。综上可见,这种可注射壳聚糖-透明质酸水凝胶在生物医药、组织功能、临床医学等领域具有广阔的应用前景。