STUDIES OF ADULT BRAIN NEUROPOIESIS

干细胞和前体细胞现在已经在成年啮齿动物和人脑中被识别出来，人们越来越有兴趣操纵这些细胞沿着特定的路线增殖和分化，这可能有利于它们用于神经系统疾病的细胞替代疗法。虽然大多数研究小组已经研究了这些细胞及其从胚胎或出生后早期大脑中体外产生的神经球，但我们的实验室专注于成人大脑中干细胞/前体细胞的存在和增殖--即所谓的神经再生。在体内室管膜下区这些细胞上和周围存在发育调节的细胞黏附和细胞外基质(ECM)分子，这表明操纵干细胞/前体细胞的黏附相互作用可能会促进它们的增殖，并在一定程度上控制它们分化为特定类型的神经元。这一建议的前提是，体外细胞外基质扰动实验、使用新型细胞饲养层和移植实验将提供不同类型的成年脑干/前体细胞的分离和鉴定，同时帮助我们指导这些细胞的生长和分化为能够整合到已建立和受损的神经元回路中的前体细胞和完全分化的细胞(如神经元)。组织培养和脑移植实验将使用正常和ECM缺陷的转基因小鼠进行：1)证明操纵ECM分子可以导致干细胞/前体细胞群体的体外扩张，并限制细胞谱系；2)测试来自非神经组织的饲养层，以释放生长因子和其他分子，帮助区分和维持培养中最原始的干细胞/前体细胞类别，以便更广泛地分析它们的自我更新、增殖和分化；3)使用饲养层和其他生长诱导底物来启动来自成人大脑的干细胞/前体细胞群，以更好地存活并作为移植物整合到成人大脑中。因此，利用新的培养方法，以及对成年脑干/前体细胞表达的细胞表型和发育基因的免疫细胞化学和分子分析，这些研究将阐明可能对这些具有潜在临床重要性的成熟人脑驻留细胞的生存和生长至关重要的因素。

Stem and precursor cells have now been identified in the adult rodent and human brain, and there is a growing interest in manipulating these cells to proliferate and differentiate along particular lines that might favor their use in cell replacement therapies for neurological disease. Whereas most groups have studied these cells and their in vitro generation of neurospheres from the embryonic or early postnatal brain, our lab has focused on the presence and proliferation of stem/precursor cells in the adult brain - so called neuropoiesis . The presence of developmentally regulated cell adhesion and extracellular matrix (ECM) molecules on and around these cells in vivo in the subependymal zone, a region we have begun to refer to as brain marrow , suggests that manipulating the adhesive interactions of stem/precursor cells might enhance their proliferation and also offer a level of control over their differentiation into, e.g., particular types of neurons. This proposal is founded on the premise that in vitro ECM perturbation experiments, use of novel cell feeder layers, and transplantation experiments will afford the isolation and characterization of distinct types of adult brain stem/precursor cells, and at the same time help us direct the growth and differentiation of these cells into progenitors and fully differentiated cells (e.g. neurons) that are able to integrate into established and compromised neuronal circuitries. Tissue culture and brain grafting experiments will be performed using normal and ECM-deficient transgenic mice to: 1) prove that manipulating ECM molecules can lead to an ex vivo expansion of stem/precursor cell populations, and also restrict cell lineage; 2) test feeder layers derived from non-neural tissues to release growth factors and other molecules that help to discriminate and sustain the most primitive classes of stem/precursor cells for extended periods of time in culture to allow more extensive analyses of their self-renewal, proliferation and differentiation; and 3) use feeder layer and other growth- inducing substrates to prime stem/precursor cell populations from the adult brain to better survive and integrate as grafts into the adult brain. Thus, using novel culture approaches, and immunocytochemical and molecular analyses of cell phenotype and developmental genes expressed by adult brain stem/precursor cells, these studies will elucidate factors that may be crucial to the survival and growth of these potentially clinically important, resident cells of the mature human brain.