Extracellular Matrix--Cell Differentiation/Embryogenesis

细胞外基质在胚胎发生和组织修复中起着重要作用。通过使用纯化组分的体外研究，我们对细胞如何粘附、迁移、增殖和分化以响应组织和细胞特异性基质分子有了更好的了解。我们发现基底膜，即所有上皮细胞和内皮细胞以及神经细胞周围的细胞外基质，在体外促进细胞分化。在基底膜上培养时，内皮细胞形成带有管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)鉴定具有生物活性的基质成分，与细胞粘附、迁移、增殖和分化有关；(2)用合成肽定位基质成分上的活性位点；(3)鉴定和表征细胞受体；(4)了解参与生物反应的细胞内事件；(5)鉴定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，包括原发性和已建立的乳腺和黑色素瘤肿瘤细胞、内皮细胞和唾液腺和细胞。我们已经在体外和体内使用内皮细胞试管实验来确定在发育、修复和疾病中调节血管形成的分子。我们的目标是发现具有生理和临床相关性的新的血管生成调节因子。我们研究了基底膜蛋白层粘连蛋白，并确定了细胞粘附和血管生成的活性位点和细胞受体。其中一些活性肽正被开发成缓释支架，用于进一步的皮肤和口腔伤口愈合体内试验。

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.