干细胞研究和应用中目前尚需解决和完善一些方面干细胞特性.pdf

干细胞研究和应用中目前尚需解决和完善的一些方面
一、干细胞的特性
1）自我更新
2）分化成特定细胞、组织
二、干细胞的来源问题
Model of Embryonic and Adult Stem-Cell Differentiation along and across Germ-Layer Boundaries.
Various Models for Generating Solid-Organ Tissue Cells through Differentiation of Bone Marrow-Derived and
Circulating Adult Stem Cells
In the first model, distinct stem cells differentiate, each into its own organ-specific cell (Panel A). In the second
model, primitive somatic stem cells located in hematopoietic tissue differentiate into various organ-specific cells
(Panel B). In the third model, stem cells, such as hematopoietic stem cells, differentiate along their predetermined
pathway. Under certain, probably rare conditions, tissue injury or another stimulus causes some stem cells to deviate
from their predetermined pathway and generate cells of a different tissue - a process known as transdifferentiation
(Panel C). In the fourth model, mature cells dedifferentiate into cells with stem-cell-like characters
Possible Roles of Bone Marrow-Derived and Circulating Stem Cells in the Repair of Solid-Organ Tissues
需要解决的问题：
1）干细胞在各种组织与器官的定位分布
Hematopoietic stem cells (HSC)造血干细胞：骨 髓、外周血、脐带间充质
Neural stem cells 神经干细胞
Hepatic stem cells 肝脏干细胞
Muscle stem cells 肌肉干细胞
Adipocyte stem cells 脂肪干细胞
embryonic SC 胚胎来源的干细胞
⋯⋯ ..
2）干细胞的来源、转化及影响因素
创伤，炎症，肿瘤
3）干细胞起源、转移、归巢
细胞动员、 细胞标记等
三、干细胞生长分化的调控问题
Sequence-specific transcription factors act as docking molecules for the recruitment of DNA and histone-modifying
activities to target gene promoters. Active transcription is associated with hyperacetylation and methylation of H3K4,
H3K79 and H3K36 residues in promoter regions, whereas gene repression is associated with DNA methylation,
hypoacetylation and methylation of H3K9, H3K27 and H4K20 residues. These modifications are mediated by
chromatin-modifying enzymes including DNA methyltransferas