Contractile cells in rat myocardial scar tissue

In earlier studies of rat myocardial tissue reactions to necrotizing injuries, we observed in the resulting scar tissue a large number of smooth muscle cells unassociated with blood vessels. Since these cells are not normal components of ventricular myocardium, we studied the appearance and fate of all cells with smooth muscle-like features in healing and healed lesions at intervals up to 10 weeks after ischemic or freeze-thaw injuries. Observations were made with light and electron microscopes, using conventional methods and immunostaining methods to detect alpha-smooth muscle actin. In healing and healed lesions, smooth muscle actin was detected histologically in capillary pericytes, myofibroblasts, and both vascular and nonvascular smooth muscle cells. Its association with cytoplasmic microfilaments in nonsarcomeric myocytoskeletal arrangements was confirmed ultrastructurally. The pericytes and myofibroblasts predominated during the earlier hypercellular healing period. The smooth muscle cells appeared near the end of the first week of repair; they were initially located mainly in presumptive vascular structures, identified by residual basal lamina sheaths, but subsequently located mainly in nonvascular locations. After the second week until the end of the study the number of nonvascular smooth muscle cells increased and that of myofibroblasts decreased. The nonvascular smooth muscle cells predominated in the larger mature scars, especially the transmural ones. From these observations, we have concluded that contractile cells other than cardiac myocytes have important roles in myocardial tissue repair, have suggested that their roles are related to the forces of myocardial contractions, and have discussed their possible functions and lineage interrelationships.     

Tumstatin对兔耳增生性瘢痕的抑制作用

目的 探讨肿瘤抑素(Tumstatin)对兔耳瘢痕组织生长情况的影响.方法 建立兔耳增生性瘢痕模型,用Tumstatin对兔耳腹侧建立的增生性瘢痕模型通过在体局部注射进行干预,随机设立Tumstatin治疗组、Tumstatin预防治疗组、曲安奈德对照组、生理盐水对照组;停止药物注射21天后各组同时于每只兔的双侧对称部位取材瘢痕组织,每一取材瘢痕组织均分成同样大小的四等份,分别进行组织形态学观察、CD34免疫组化方法测定血管密度的变化、观察血管内皮细胞与成纤维细胞凋亡的变化情况.结果 Tumstatin预防治疗组和Tumstatin治疗组中,新生毛细血管密度、内皮细胞活性以及成纤维细胞数量都较曲安奈德和生理盐水对照组明显降低,差异有统计学意义(P<0.05).结论 Tumstatin能够较曲安奈德更明显地抑制增生性瘢痕的生长,为Tumstatin用于防治增生性瘢痕的可行性提供了初步的理论依据.     

Finite element modeling of drug distribution in the vitreous humor of the rabbit eye

Direct intravitreal injection of drug is a common method for treating diseases of the retina or vitreous. The stagnant nature of the vitreous humor and surrounding tissue barriers creates concentration gradients within the vitreous that must be accounted for when developing drug therapy. The objective of this research was to study drug distribution in the vitreous humor of the rabbit eye after an intravitreal injection, using a finite element model. Fluorescein and fluorescein glucuronide were selected as model compounds due to available experimental data. All required model parameters were known except for the permeability of these compounds through the retina, which was determined by fitting model predictions to experimental data. The location of the intravitreal injection in the experimental studies was not precisely known; therefore, several injection locations were considered, and best-fit retinal permeability was determined for each case. Retinal permeability of fluorescein and fluorescein glucuronide estimated by the model ranged from 1.94×10⁻⁵ to 3.5×10⁻⁵ cm s⁻¹ and from 0 to 7.62×10⁻⁷ cm s⁻¹, respectively, depending on the assumed site of the injection. These permeability values were compared with values previously calculated from other models, and the limitations of the models are discussed. Intravitreal injection position was found to be an important variable that must be controlled in both experimental and clinical settings.     

磷脂多不饱和脂肪酸抑制兔耳增生性瘢痕

背景：多不饱和脂肪酸有抑制细胞炎症反应及免疫功能的作用,增生性瘢痕的形成与炎症、细胞免疫、细胞因子有着密切关系,但目前尚无应用多不饱和脂肪酸防治增生性瘢痕的实验研究。 目的：探讨磷脂多不饱和脂肪酸对兔耳增生性瘢痕的抑制作用。 方法：在9只新西兰大白兔兔耳腹侧做直径1 cm的圆形全层皮肤缺损创面,每侧6个,共108个,其中形成增生性瘢痕92个,瘢痕形成率为85%。实验分3组：每只兔耳靠前3个创面涂磷脂多不饱和脂肪酸霜,右耳靠后3个创面涂多磺酸黏多糖乳膏,创面上皮化后立即涂药,每日1次,左耳靠后3个创面自然愈合。分别在术后28,42,63,90 d,观察创面的愈合情况;显微镜下观察瘢痕组织的厚度、胶原纤维和成纤维细胞密度;免疫组织化学染色检测胶原纤维的表达。 结果与结论：涂抹磷脂多不饱和脂肪酸霜和多磺酸黏多糖乳膏可使增生性瘢痕体积缩小、厚度变薄、成纤维细胞密度减小、胶原纤维表达减少。尤以磷脂多不饱和脂肪酸霜的效果最为明显。说明磷脂多不饱和脂肪酸可抑制兔耳增生性瘢痕的形成,减轻瘢痕的增生程度。     

细菌纤维素减轻兔耳增生性瘢痕的作用

背景：国内外已有研究报道细菌纤维素对皮肤创伤愈合具有促进作用,但是其对增生性瘢痕是否有治疗作用尚不清楚。 目的：观察细菌纤维素对兔耳增生性瘢痕的疗效。 方法：建立兔耳腹侧增生性瘢痕模型,术后第21天创面上皮化后,对每只兔耳5个不同瘢痕面随机给予5种不同处理方式：持水性分别为1∶5,1∶6,1∶8细菌纤维素组、阳性对照组(贴敷瘢痕贴)、阴性对照组(未贴任何敷料且瘢痕自然生长)。观察不同处理后第0,14,21,28,42,56天瘢痕面大体形态学及组织学变化。 结果与结论：持水性1∶5,1∶6,1∶8细菌纤维素组瘢痕增生厚度低于阴性对照组,但高于阳性对照组(P < 0.01)。与阴性对照组比较,持水性1∶5,1∶6,1∶8细菌纤维素组瘢痕组织中真皮层薄,成纤维细胞少,胶原纤维较细、排列较整齐;与阳性对照组组比较,持水性1∶5,1∶6,1∶8细菌纤维素组成纤维细胞数稍多,胶原也稍粗、排列也稍不整齐。3种细菌纤维素组间瘢痕厚度及成纤维细胞数量为1∶5细菌纤维素组> 1∶6细菌纤维素组> 1∶8细菌纤维素组(P  < 0.05)。说明细菌纤维素有效抑制了兔耳创面愈合后增生性瘢痕的形成,并且持水性越高,效果越好。     

Matrix metalloproteinases: a role in the contraction of vitreo-retinal scar tissue

The most common cause of failure of retinal reattachment surgery is formation of fibrocellular contractile membranes on both surfaces of the neuroretina. This intraocular fibrosis, known as proliferative vitreoretinopathy, results in a blinding tractional retinal detachment because of the contractile nature of the membrane. Contractility is a cell-mediated event that is thought to be dependent on locomotion and adhesion to the extracellular matrix. Interactions between cells and the extracellular matrix can be influenced by matrix metalloproteinases (MMPs) and we investigated the role of MMPs in two in vitro models (two- and three-dimensional) of human retinal pigment epithelial (RPE) cell-mediated contraction. MMP activity was detected using enzyme-linked immunosorbent assays and zymography techniques that revealed MMP-1, -2, -3, and -9 positivity during the collagen matrix contraction assays. RPE-populated collagen matrix contraction (three-dimensional) was inhibited using a cocktail of anti-MMP antibodies and with Galardin (a broad-spectrum MMP inhibitor). Galardin inhibition was dose-dependent, reversible, and dependent on cell number. MMP inhibitors had no effect on contraction when RPEs were seeded on two-dimensional collagen matrices or on cellular adhesion to collagen type I. Our results suggest that MMP activity may be required for three-dimensional but not two-dimensional RPE-collagen matrix contraction.     

重组人血管内皮抑制素可抑制兔耳增生性瘢痕

背景：增生性瘢痕局部血流量明显增高,微血管密度明显高于萎缩期及成熟的正常瘢痕。 目的：观察重组人血管内皮抑制素对新西兰大耳兔兔耳增生性瘢痕的抑制作用及其对瘢痕中血管内皮生长因子的作用。 方法：建立兔耳增生性瘢痕动物模型。随机分为2组,实验组局部注射重组人血管内皮抑制素,对照组局部注射生理盐水。 结果与结论：药物干预后30 d实验组兔耳瘢痕较对照组颜色变淡、质地柔软、厚度薄。苏木精-伊红染色实验组真皮层较对照组薄,单位面积内成纤维细胞数较对照组少,呈平行排列,毛细血管管径较对照组细;实验组瘢痕增生指数显著低于对照组(P < 0.01)。实验组瘢痕组织血管内皮生长因子阳性表达量显著低于对照组(P < 0.01)。说明重组人血管内皮抑制素注射液可能通过降低血管内皮生长因子蛋白的表达,从而抑制兔耳增生性瘢痕组织增生。     

Fibrogenic cytokines: the role of immune mediators in the development of scar tissue

A variety of diseases that are characterized by fibrosis share common features including the proliferation of fibroblasts and the deposition of extracellular matrix. Fibrosis often begins as an inflammatory reaction with leukocyte infiltration followed by the elaboration of cytokines. Here, Elizabeth J. Kovacs argues that the aberrant production of these mediators sustains the connective tissue accumulation that results in permanent alteration in tissue structure and function.     

Connective tissue growth factor participates in scar formation of crescentic glomerulonephritis

Glomerular crescents are a major determinant of progression in various renal diseases. Some types of growth factors are known to be involved in the evolution of crescents and the subsequent scar formation. Although glomerular parietal epithelial cells (PECs) are the major component of cellular crescents, the influence of growth factors on PECs is unknown. We performed immunohistochemical studies and in situ hybridization to examine alterations in connective tissue growth factor (CTGF) expression and to identify CTGF-synthesizing cells in crescents in the crescentic glomerulonephritis model of Wistar Kyoto rats. In addition, we examined the roles of fibroblast growth factor (FGF)-2, platelet-derived growth factor (PDGF)-BB, transforming growth factor (TGF)-beta, and CTGF in cell proliferation and matrix synthesis in an established rat PEC cell line (PEC line). In an acute phase of rat crescentic glomerulonephritis, a major component of the crescents were macrophages, which did not express CTGF mRNA. However, in the advanced phase, crescents strongly expressed CTGF mRNA and the epithelial marker pan-cadherin but did not express the macrophage marker ED1, suggesting that PECs synthesized the CTGF. In the PEC line, FGF-2 predominantly promoted [(3)H]thymidine incorporation compared with PDGF-BB. Both TGF-beta and PDGF-BB strongly stimulated extracellular matrix synthesis in association with up-regulation of endogenous CTGF, but TGF-beta showed a predominant role. FGF-2 had a minor effect on it. In addition, blockade of endogenous CTGF using an antisense oligodeoxynucleotide significantly attenuated both TGF-beta- and PDGF-BB-induced extracellular matrix synthesis. These results suggest that several growth factors promote cell proliferation and matrix production in PECs. CTGF-mediated matrix production via the TGF-beta or PDGF-BB pathway in PECs may, in part, play a role in the progression of scar formation in crescents.     

Apoptosis mediates the decrease in cellularity during the transition between granulation tissue and scar.

Granulation tissue formation and contraction is an important step of second intention wound healing. Granulation tissue develops from the connective tissue surrounding the damaged or missing area and its cellular components are mainly small vessel and inflammatory cells as well as fibroblasts and myofibroblasts. As the wound closes and evolves into a scar, there is an important decrease in cellularity; in particular myofibroblasts disappear. The question arises as to which process is responsible for this cellular loss. During a previous investigation on the expression of alpha-smooth muscle actin in myofibroblasts (Darby I, Skalli O, Gabbiani G, Lab Invest, 1990, 63:21-29), we have observed that in late phases of wound healing, many myofibroblasts show changes compatible with apoptosis and suggested that this type of cell death could be responsible for the disappearance of myofibroblasts. We have now tested this hypothesis by means of morphometry at the electron microscopic level and by in situ end labeling of fragmented DNA. Our results indicate that the number of myofibroblastic and vascular cells undergoing apoptosis increases as the wound closes and support the assumption that this is the mechanism of granulation tissue evolution into a scar. The regulation of apoptotic phenomena during wound healing may be important in scar establishment and development of pathological scarring.     

Thyroid hormone-sensitive brown adipose tissue respiration in the newborn rabbit

The effects of thyroid hormone treatment on brown adipose tissue (BAT) and liver metabolism were assessed by measuring oxygen consumption, sodium-potassium adenosine triphosphatase (Na-K-ATPase), and mitochondrial alpha-glycerophosphate dehydrogenase (alpha-GPD) activities in tissues from triiodothyronine- (T3) and vehicle-injected (for 3 days) newborn and adult rabbits. In the newborns, basal BAT cellular respiration was increased [mean (%/- SE) = 119 +/- 18 vs. 65 +/- 4 microliter O2/10(6) cells-1 . h in controls (P less than 0.005)], whereas hepatic respiration was unchanged. Ouabain had no effect on basal BAT cellular respiration, but suppressed hepatic respiration by 30% in both newborn groups. T3 treatment had no effect on NE- (10(-6) M) stimulated BAT respiration, whereas adult hepatic respiration was increased almost twofold. alpha-GPD activities were increased in both newborn BAT and adult liver but not in newborn liver. Na-K-ATPase activity was significantly increased only in newborn liver. In conclusion, 1) both BAT and liver are thyroid-hormone sensitive in the newborn rabbit, but the responses to T3 treatment are different in the two tissues; 2) the failure to stimulate both hepatic alpha-GPD and respiration in the newborn appears to be a developmental phenomenon characteristic of the rabbit; 3) thyroid hormones have little effect on sodium transport-dependent respiration in either BAT of liver in the newborn rabbit.     

A rabbit model to tissue engineer the bladder

A rabbit model was used for the evaluation of a collagen-based biomatrix of small intestinal submucosa (SIS, COOK) in comparison to a biochemically reconstructed biomatrix for bladder tissue regeneration. Rabbits underwent partial cystectomy and cystoplasty with SIS patch graft or with a biochemically defined collagen biomatrix. The grafts of the regenerated bladder wall were harvested at different intervals and tissue regeneration was evaluated. The results of the SIS and biochemically defined biomatrix grafts were comparable. At harvesting, we found five bladder stones and encrustation of the biomatrix in 21/56 animals. No stone formation was observed in the control group. The results of the molecularly defined biomatrix are thus far comparable to SIS. Both matrices show good epithelialization and ingrowth of smooth muscle cells. Both biomatrices show considerable encrustation, which appears to disappear in time. The rabbit model is suitable for bladder tissue engineering studies as it is an easy model to use. In this model, besides tissue regeneration, also some of the clinical problems are seen such as encrustation of foreign body material in the bladder. These aspects are subject for further pre-clinical studies in this animal model.     

Clinical device-related article evaluation of morphology and functions of a foldable capsular vitreous body in the rabbit eye

We previously proposed a new strategy to replace a vitreous body with a novel foldable capsular vitreous body (FCVB). In this study, the FCVB was designed to mimic natural vitreous morphology, and evaluate its physiological functions compared with traditional silicone oil substitutes, in an established rabbit model of proliferative vitreoretinopathy. We found that FCVB was a very good replacement for closely mimicking the morphology and restoring the physiological functions, such as the support, refraction, and cellular barriers, of the rabbit vitreous body. The study has provided us with a novel research and therapy strategy that could effectively mimic the morphology and physiological function of the rabbit vitreous body.     

Ski, a modulator of wound healing and scar formation in the rat skin and rabbit ear

We recently demonstrated that Ski is a novel wound healing-related factor that promotes fibroblast proliferation and inhibits collagen secretion. Here, we show that increasing local Ski expression by gene transfer not only significantly accelerated wound healing by relieving inflammation, accelerating re-epithelialization and increasing formation of granulation tissue, but also reduced scar formation by decreasing collagen production in rat dermal wounds. Similarly, ski gene transfer accelerated wound healing, reduced the protuberant height and volume of scars and increased collagen maturity in a hypertrophic scar model in the rabbit ear. Conversely, reducing Ski expression in the wound by RNA interference resulted in significantly slower wound healing and increased scar area in rat dermal wounds. We demonstrated that these effects of Ski are associated with transforming growth factor-β-mediated signalling pathways through both Smad2/3-dependent and Smad-independent pathways. Together, our results define a dual role for Ski in promoting wound healing and alleviating scar formation, identifying a new target for therapeutic approaches to preventing scar hyperplasia and accelerating wound healing.     

隐丹参酮抑制模型兔耳增生性瘢痕的作用及机制

BACKGROUND: Cryptotanshinone (CTS) has been shown to have a certain inhibitory effect on hyperplastic scar hyperplasia, but the specific mechanism is still unclear. OBJECTIVE: To investigate the inhibitory effect of CTS on hypertrophic scar of the rabbit ear and its effect on transforming growth factor-β1/Smads signaling pathway. METHODS: The rabbit ear model of hypertrophic scar was established and then rabbit models were randomly divided into model group, low and high-dose CTS groups, followed by local injection of normal saline, 27 and 81 mg/L CTS respectively beginning at 21 days after modeling, once a day, for 7 days. Meanwhile, normal rabbits were used as the control group. Scar index was measured after administration. Pathological analysis was carried out by hematoxylin-eosin staining and Masson staining after sampling. The expression of α-smooth muscle actin was detected by immunohistochemistry. Hydroxyproline content was determined by alkaline hydrolysis. The expression of type I collagen, type III collagen and transforming growth factor-β1/Smads signaling pathway related proteins were detected by western blot. RESULTS AND CONCLUSION: Compared with the control group, the scar index, the number of fibroblasts and collagen fibers were significantly increased, the levels of α-smooth muscle actin and hydroxyproline in scar tissue, and the protein levels of type I collagen, type III collagen, transforming growth factor-β1, p-Smad2, p-Smad3 and Smad4 were significantly increased in the model group (P < 0.05). Compared with the model group, the scar index, the number of fibroblasts and collagen fibers were significantly decreased, the levels of α-smooth muscle actin and hydroxyproline in scar tissue, and the protein levels of type I collagen, type III collagen, transforming growth factor-β1, p-Smad2, p-Smad3 and Smad4 were significantly decreased in the low and high-dose CTS groups (P < 0.05). The above-mentioned parameters changed more significantly in the high-dose CTS group compared to the low-dose CTS group (P < 0.05). To conclude, CTS has a certain inhibitory effect on the formation of hypertrophic scar in rabbit ears, and its mechanism may be related to transforming growth factor-β1/ Smads signaling pathway. © 2021, Journal of Clinical Rehabilitative Tissue Engineering Research. All rights reserved.     

Rhythmic changes of morphometric parameters of rat cardiac scar connective tissue

Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 115, N ^o 2, pp. 213–214, February, 1993