Origin of the Dermal Fibroblast

描述（由申请人提供）：干细胞生物学的最新研究进展提高了以细胞为基础的治疗人类疾病的希望。虽然胚胎干细胞在组织工程和更成功地管理各种疾病的发病机制方面具有巨大的潜力，但从胚胎后组织中分离出来的许多政治和干细胞规避了这些问题。关于皮肤纤维化疾病，一个主要特征是真皮成纤维细胞过度沉积细胞外基质。在系统性硬化症（SSc）或硬皮病中，与真皮成纤维细胞功能失调相关的分子和细胞机制尚不清楚，然而，有假设认为一种可能的机制是真皮成纤维细胞亚群异常激活以产生过量基质。由于硬皮病主要表现为成人，这种激活是否会发生在成纤维细胞祖细胞水平上，从而导致过度活跃的基质生成细胞亚群的产生？作为解决这个问题的第一步，必须开发关于真皮成纤维祖细胞的基本信息。真皮成纤维细胞干细胞是严格意义上的真皮起源，还是真皮外起源，或者两者兼而有之？这项拨款提案将验证真皮成纤维细胞干细胞至少部分来源于真皮外，并且可能来源于骨髓的假设。为了解决这些假设，已经制定了两个具体目标。一个目的是利用异种小鼠模型来确定皮外前体是否存在于外周循环中。异种配对将通过手术产生，其中一方携带ColGFP（在真皮成纤维细胞中表达），另一方是非转基因的。在每天注射博来霉素诱导纤维化病变后，将对异种共生对的两个成员的皮肤样本进行GFP表达评估。非转基因配对体中GFP表达的存在与真皮成纤维细胞的真皮外起源一致，这些祖细胞自由循环。为了评估骨髓可能是参与真皮纤维化的细胞的皮外来源这一假设，骨髓嵌合体将通过骨髓移植产生。非转基因受体将接受从转基因供体小鼠分离的骨髓细胞制剂（ColGFP）的注射。骨髓嵌合成功建立后，局部注射博来霉素可再次诱导皮肤纤维化病变。在诱导纤维化病变的真皮成纤维细胞中观察到的GFP表达与骨髓可以是真皮成纤维细胞祖细胞来源的假设是一致的。预计在这些研究中收集的数据将有助于我们了解真皮成纤维细胞的起源。这项与公共卫生相关的研究的长期目标是了解真皮成纤维细胞的起源，真皮成纤维细胞是维持皮肤完整性的重要细胞，并确定与真皮成纤维细胞干细胞分化为成熟基质生成细胞相关的细胞和分子机制。我们认为这些知识对于开发新的治疗方法来治疗纤维化皮肤病（如硬皮病）以及涉及产生结缔组织的细胞的其他潜在疾病至关重要。

DESCRIPTION (provided by the applicant): Recent research advances in stem cell biology have raised the promise of cell-based therapies for the treatment of human diseases. While embryonic stem cells hold great potential for tissue engineering and more successfully managing the pathogenesis of various diseases, numerous political and of isolated from post-embryonic tissues circumvent some of these problems. With regard to fibrotic diseases of the skin, a cardinal feature is the excessive deposition of extracellular matrix by dermal fibroblasts. In one disease, systemic sclerosis (SSc) or scleroderma, the molecular and cellular mechanisms associated with this dysregulation of dermal fibroblast function are not clearly understood, however, it has been hypothesized that one possible mechanism is the abnormal activation of a subset of dermal fibroblasts to produce excess matrix. Since scleroderma is largely adult in presentation could this activation occur at the level of a fibroblast progenitor cell leading to the production a sub-population of hyperactive matrix producing cells? As first step toward addressing this question, basic information on dermal fibroblast progenitor cells must be developed. Are dermal fibroblast stem cells strictly dermal in origin or do they have an extra-dermal origin or a combination of the two? This grant proposal will test the hypothesis that dermal fibroblast stem cells are at least in part extra-dermal in origin and this origin is potentially the bone marrow. Two specific aims have been developed to address these hypotheses. One aim will utilize a parabiotic mouse model to determine if extra-dermal precursors are resident in the peripheral circulation. Parabiotic pairs will be surgically created, with one partner bearing a ColGFP (expressed in the dermal fibroblast) and the other partner being non-transgenic. Following the induction of fibrotic lesions by daily injections of bleomycin, skin samples from both members of the parabiotic pair will be evaluated for GFP expression. The presence of GFP expression in the non-transgenic parabiont is consistent with an extra-dermal origin of dermal fibroblasts and these progenitors freely circulate. To assess the hypothesis that bone marrow may be an extra-dermal source of cells participating in dermal fibrosis, bone marrow chimeras will be created via a bone marrow transplant. Non-transgenic recipients will receive injections of bone marrow cell preparations isolated from transgenic donor mice (ColGFP). After bone marrow chimerism has be successfully established, fibrotic lesions in the skin will again induced by local bleomycin injections. An observation of GFP expression in dermal fibroblasts in the induced fibrotic lesion is consistent with the hypothesis that the bone marrow can be a source of dermal fibroblast progenitors. It is anticipate that data collected in these studies will contribute to our knowledge of the origin of dermal fibroblasts. The long-term objective of this research as it relates to public health is to understand the origin of the dermal fibroblast, a cell important in the maintenance of the integrity of the skin and to determine the cellular and molecular mechanisms associated with differentiation of a dermal fibroblast stem cell into a mature matrix producing cell. We feel this knowledge is essential for the development of novel therapeutic approaches for the management of fibrotic skin diseases such as scleroderma as well as other potentially other conditions involving cells that produce connective tissue.