Extracellular Matrix--Cell Differentiation/Embryogenesis

细胞外基质在胚胎发育和组织修复中非常重要。通过使用纯化成分的体外研究，对细胞如何黏附、迁移、增殖和分化以响应组织和细胞特定的基质分子已经有了更好的理解。我们发现基底膜在体外促进细胞分化，基底膜是细胞外基质，位于所有上皮细胞和内皮细胞之下，包围着神经细胞。当培养在基底膜上时，内皮细胞形成带腔的毛细血管样结构，软骨细胞形成软骨，唾液细胞形成腺体等。我们的目标是确定参与这一过程的分子和细胞事件。我们的方法是(1)识别与细胞黏附、迁移、增殖和分化有关的生物活性基质成分，(2)用合成肽定位基质成分上的活性部位，(3)识别和表征细胞受体，(4)了解参与生物反应的细胞内事件，以及(5)识别由细胞外基质诱导的基因。我们在几个体外模型系统中工作，包括原代和已建立的乳腺和黑色素瘤肿瘤细胞、内皮细胞以及唾液腺和细胞。我们使用了体外血管内皮细胞管实验和体内血管生成实验来定义在发育、修复和疾病中调节血管形成的分子。我们的目标是发现新的具有生理和临床意义的血管生成调节因子。我们研究了基底膜蛋白-层粘连蛋白，并确定了细胞黏附和血管生成的活性部位和细胞受体。其中一些活性多肽正在被开发成缓释支架，用于进一步在体内测试皮肤和口腔的伤口愈合。 我们还重点研究了一种名为胸腺素β4的基因，它是由内皮细胞在基底膜基质上分化为毛细血管样结构时诱导的。我们发现胸腺素β4通过增加血管生成和角质形成细胞迁移来促进皮肤创伤修复。它促进正常动物的伤口修复，以及伤口愈合延迟的动物，包括糖尿病和老年动物。胸腺肽β4还促进老年动物和环磷酰胺治疗的动物的毛发生长，环磷酰胺是化疗导致脱发的模型。裸鼠的毛发生长也受到刺激，因为裸鼠缺少丰富的毛轴。我们已经确定了该蛋白的活性部位为一个七个氨基酸的肌动蛋白结合域。细胞受体可能是表面肌动蛋白。我们现在已经创造了一只转基因小鼠，它在皮肤中过度表达这种蛋白质。这只老鼠在剃毛后似乎加速了伤口的愈合和毛发的再生。出乎意料的是，转基因小鼠也有牙齿发育异常，我们目前正在进行调查。这种蛋白质目前处于糖尿病和老年患者伤口愈合的第二阶段人体临床试验中。我们的目标是了解细胞外基质如何调节组织的形成、修复和某些病理过程。我们还希望开发用于皮肤和口腔伤口愈合的新疗法。

The extracellular matrix is important in embryogenesis and in tissue repair. From in vitro studies using purified components, a better understanding of how cells adhere, migrate, proliferate, and differentiate in response to tissue and cell- specific matrix molecules has been established. We have found that the basement membrane, the extracellular matrix which underlies all epithelial cells and endothelial cells and surrounds nerve cells, promotes cell differentiation in vitro. When cultured on basement membrane, endothelial cells form capillary-like structures with a lumen, chondrocytes form cartilage, salivary cells form glands, etc. Our goal is to define the molecular and cellular events involved in this process. Our approach has been (1) to identify the biologically active matrix components, with respect to cell adhesion, migration, proliferation, and differentiation, (2) localize active sites on the matrix component with synthetic peptides, (3) identify and characterize cellular receptors, (4) gain an understanding of the intracellular events involved in the biological response, and (5) identify genes induced by the extracellular matrix. We work in several in vitro model systems including primary and established breast and melanoma tumor cells, endothelial cells, and salivary glands and cells. We have used the endothelial cell tube assays in vitro and in vivo angiogenesis assays to define molecules which regulate vessel formation in development, repair, and disease. Our goal is to discover new angiogenic regulators that have physiological and clinical relevance. We have worked with the basement membrane protein laminin and identified active sites and cellular receptors for cell adhesion and angiogenesis. Some of these active peptides are being developed into slow release scaffolds for further in vivo testing for wound healing in the skin and in the oral cavity. We have also focused on a gene, thymosin beta 4, that is induced by endothelial cells as they differentiate into capillary-like structures on a basement membrane substratum. We find that thymosin beta 4 promotes dermal wound repair via increased angiogenesis and keratinocyte cell migration. It promotes wound repair in normal animals as well as in animals with delayed wound healing, including diabetic and aged animals. Thymosin beta 4 also promotes hair growth in aged animals and in animals treated with cyclophosphamide, which is a model for chemotherapy-induced hair loss. Hair growth is also stimulated in athymic nude mice which lack abundant hair shafts. We have identified the active site on this protein to a seven amino acid actin binding domain. The cellular receptor may be surface actin. We now have created a transgenic mouse which over-expresses this protein in its skin. The mouse appears to have accelerated wound healing and hair regrowth after shaving. Unexpectedly, the transgenic mouse also has abnormal tooth development which we are currently investigating. This protein is currently in phase 2 human clinical trials for wound healing for diabetic and aged patients. Our goal is to understand how the extracellular matrix regulates tissue formation, repair, and certain pathological processes. We also hope to develop novel therapeutics for dermal and oral wound healing.