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基于细胞的疗法治疗人类疾病的前景。虽然胚胎干细胞在组织工程和更成功地处理各种疾病的发病机制方面具有巨大的潜力，但从胚胎后组织分离出来的许多政治和技术方法绕过了其中一些问题。关于皮肤纤维性疾病，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，有人假设其中一个可能的机制是真皮成纤维细胞亚群异常激活，产生过量基质。由于硬皮病主要表现为成人，这种激活可能发生在成纤维细胞前体细胞的水平上，从而产生一个亚群的高活性基质产生细胞吗？作为解决这个问题的第一步，必须开发关于真皮成纤维细胞前体细胞的基本信息。真皮成纤维细胞干细胞是严格意义上的真皮来源，还是真皮外来源，还是两者的结合？这项拨款提案将检验这样一种假设，即真皮成纤维细胞至少部分起源于真皮外，这个来源可能是骨髓。为了解决这些假设，已经制定了两个具体目标。一个目标是利用异种生物小鼠模型来确定外周循环中是否存在真皮外前体。将通过手术创造共生配对，其中一个配对携带ColGFP(在真皮成纤维细胞中表达)，另一个配对是非转基因的。在每天注射博莱霉素诱导纤维化病变后，将对两个副生物对成员的皮肤样本进行GFP表达评估。GFP在非转基因副生物中的表达与真皮外成纤维细胞的来源一致，并且这些祖细胞可以自由循环。为了评估骨髓可能是参与真皮纤维化的真皮外细胞来源的假设，将通过骨髓移植创造骨髓嵌合体。非转基因受者将接受从转基因供体小鼠分离的骨髓细胞制剂(ColGFP)的注射。在成功建立骨髓嵌合体后，局部注射博莱霉素将再次引起皮肤的纤维化损害。在诱导的纤维化病变中，观察到真皮成纤维细胞中GFP的表达，这与骨髓可能是真皮成纤维细胞前体细胞的假设一致。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。这项研究涉及公共健康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产生细胞相关的细胞和分子机制。我们认为，这一知识对于开发新的治疗方法，以管理硬皮病等纤维性皮肤病以及其他涉及产生结缔组织的细胞的潜在疾病至关重要。

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.