细胞分化-细胞生物学-课件2-13.ppt

干细胞的类型： 胚胎干细胞 embryonic stem cells 胚胎干细胞主要是指来自囊胚内细胞团的细胞，有自我更新和多向分化潜能，可以分化为内、中、外三个胚层的各类细胞。 成体干细胞 adult stem cells 成体干细胞是处于干细胞状态的成体细胞，包括成年和未成年动物组织中的各种干细胞，因此又称为组织干细胞。如神经干细胞、 造血干细胞 、 骨髓间质干细胞、上皮干细胞 、肝干细胞、胰腺干细胞等。 成体干细胞的概念 成体干细胞又称组织干细胞，传统的观念认为它们是存在于成体组织的未分化细胞，现在认为也包括未成年动物的组织干细胞，它们具有不断增殖和自我更新能力、又具有多向分化潜能。 如造血干细胞、骨髓间质干细胞、神经干细胞、脂肪干细胞、上皮干细胞、胰腺干细胞、肝干细胞等 成体干细胞的功能 自然条件下成体干细胞倾向于分化成所在组织的细胞，参与组织更新和损伤修复； 外界条件诱导下成体干细胞可横向分化成其他组织的细胞，参与这些组织的损伤修复。 表皮干细胞的分化 Science. 1992 Mar 27;255(5052):1707-10 Neurogenesis in the mammalian central nervous system is believed to end in the period just after birth; in the mouse striatum（纹状体） no new neurons are produced after the first few days after birth. In this study, cells isolated from the striatum of the adult mouse brain were induced to proliferate in vitro by epidermal growth factor. The proliferating cells initially expressed nestin, an intermediate filament found in neuroepithelial stem cells, and subsequently developed the morphology and antigenic properties of neurons and astrocytes. Newly generated cells with neuronal morphology were immunoreactive for gamma-aminobutyric acid and substance P, two neurotransmitters of the adult striatum in vivo. Thus, cells of the adult mouse striatum have the capacity to divide and differentiate into neurons and astrocytes. Cell. 1999 Jan 8;96(1):25-34 New neurons are continuously added in specific regions of the adult mammalian central nervous system. These neurons are derived from multipotent stem cells whose identity has been enigmatic. In this work, we present evidence that ependymal cells (室管膜细胞) are neural stem cells. Ependymal cells give rise to a rapidly proliferating cell type that generates neurons that migrate to the olfactory bulb. In response to spinal cord injury, ependymal cell proliferation increases dramatically to generate migratory cells that differentiate to astrocytes and participate in scar formation. These data demonstrate that ependymal cell