胚胎干细胞

The four essential processes by which a multicellular organism is made:
Cell proliferation, Cell specialization, Cell interaction, and Cell movement.
Cell differentiation occurs in multicellular organisms
• Purpose of therapeutic cloning is to harvest ES cells for treatment blastocyst destroyed
• Purpose of reproductive cloning is to make new person blastocyst implanted in uterus
细胞 committed stem cell
Some stem cells have more developmental options than others
Where to get the stem cells?
(1) Embryonic stem cells
来自早期胚胎、原 始生殖细胞或畸胎 瘤组织等源于胚胎 的干细胞，属全能 干细胞totipotent， 每个细胞可以发育 成为完整的个体。
(2) Adult stem cells
存在于成体组织中， 属单能committed或多 能干细胞multipotent， 可以定向分化为一种 或几种不同的组织,如 造血干细胞，神经干 细胞等
(3) Umbilical cord blood stem cells (4) Fetal stem cells
Human: 1014 cells, >200 cell types
Transdifferentiation: From one type of cell into another type
Includes: Dedifferentiation---Redifferentiation
去分化ቤተ መጻሕፍቲ ባይዱ
再分化
What is a stem cell?
Sources of ES cells
• ES cell lines • Excess embryos from IVF clinics • Embryos created for research by IVF • Therapeutic cloning
Cloning
Reproduced by permission of the NIH
Stem cell plasticity
Adult stem cells can differentiate into a large number of different cell types.
Turning blood into brain: Science, 2000, 290: 1779-1782
Differences in mRNA expression patterns among different cell types.
Different cell types synthesize different sets of proteins.
Gene expression can be regulated at many of the steps in the pathway from DNA to RNA to protein.
Embryonic vs adult stem
cells
ES cells come from ICM of blastocyst
• ES cells are pluripotent • AS cells found in small amounts throughout
body • Most AS cells appear to be multipotent
The different cell types of a multicellular organism contain the same DNA.
A cell can change the expression of its genes in response to external signals.
Turning brain into blood: Science, 1999, 283: 534-535 NSC+EGF & FGF: Growing
mouse nerve cells
干细胞功能分类 • Totipotent stem cell: 全能干细胞, 如受精卵 • pluripotent stem cell: 多能干细胞，如囊胚中
的内囊细胞 multipotent stem cell • Unipotent stem cell: 专能干细胞，如造血干
干细胞理论与技术
Cell differentiation
About the concept of cell differentiation
The process that a cell changes to carry out a specialized function: Marked by: Morphology / Structure / Function
• Stem cells have the ability to self-renewal
• Stem cells can become other types of cells
• Stem cells can also
divide indefinitely
• Stem cells also have the unique ability to divide indefinitely, producing an unlimited number of identical undifferentiated stem cells. This is called a stem cell line.