1. . Replace Damaged Cell Organs

2. Introduce some new words The function and the prospect Stem cell The procedure Some question

3. Immunologic rejection 免疫反应 Organ transplant 器官移植 Recipient 接收者 donor 供给者 Blood-forming bone marrow tissue 造血骨髓组织 Hematopoietic stem cells(HSCs) 造血干细胞 Embryonic stem cells (ESCs) 胚胎干细胞

4. Somatic cell 体细胞 oocyte 卵母细胞 liver cell 肝细胞 Fertilized egg 受精卵 ovary 卵巢 Proliferate 增殖 Differentiate 分化 specialize 特化

5. The function and prospect When a person loose his heart or liver …… when a person have a serious damage on his organ,…….. When a person suffer a cancer disease, leukaemia( 白血病）, malignant tumor( 恶性肿瘤 ),Parkinson’s disease …….

6. is one of the great successes of modern medicine !!

7. However………. where are the enough donors’organ ?….. Although, there are enough …… there is a high risk of immunologic rejection !! So….. w e imagine …….. Whether exist a kind of cells, we can grow the cells and organ in the laboratory. If it exist ……then we can ……f

8. What’s the Stem Cells? undifferentiated cells Can self-renewal(production of cells like themselves) Can differentiate into two or more mature cell types

10. Some types of important stem cells Hematopoietic stem cells (HSCc) Cells that are normally responsible for replacing the red and white blood cells that age and die every day in our bodies.(it was well used to treat the leukaemia and other blood disease) Neural stem cells like HSCc, can proliferate in a laboratory culture dish and can be kept undifferentiated or induced to differentiate into specialize cell types(have a great contribute to treat Parkinson’s disease)

11. Show a normal human brain A person with parkinson ’ disease,but,on one side,it received the nerve cells ten years ago !

12. Embryonic stem cells (ESc) 胚胎干细胞 Cells that are isolate from very young mammalian( 哺乳动物 ), which are capable of differentiating into every type of cell in the body,either in culture or within a host embryo. Adult stem cells have a lower differentiation and proliferation capacity compared with the Esc, but they can be isolate from the individual who is being treated and,thus,will not face immunologic refection when used in subsequent cell replacement.

13. The procedure remove somatic cells from the recipient,pick up the nucleus Transfer the nucleus to the donor oocyte whose own nucleus had been removed Allow to develop into an early embryo and form many ES cells Grow ES cells in culture and induce to differentiate into the required cells(eg.blood cells, liver cells,nerve cells) Transplant the differentiated cells back into patient to restore organ function

15. Some questions ethical issues Human ES cells are derived from embryos !!! Should we destroy human embryos ?? Can we take the adult stem cells instead of the ES cells?? What are the differences between the Esc and the adult stem cells??

16. technical obstacles How to exactly induce the cells to differentiate into the required organ ? ?

17. technical obstacles Firstly,.these cells can be obtained only from very early embryos and, although several human ES-cell lines have been made, they will not be immunologically compatible with most patients who require cell transplants. So researchers will need either to derive many more ES-cell lines or to customize ES cells on a patient-by- patient basis by 'therapeutic cloning'.

18. technical obstacles Second, undifferentiated ES cells form teratomas （畸瘤） — benign tumours containing a mixture of tissue types — after being transplanted. Thus ES cells must be reliably differentiated into the appropriate cell type in culture before transplantation.( 即先要进行纯化和克隆成体 干细胞 )

19. technical obstacles Moreover, until now it had not been proved that specialized cells derived from cultured ES cells can actually function within tissues after transplantation

20. Any how Replacing damaged cell and organs is full of challenge as well as it has a great and broad prospect !!! I believe one day we can crack the hard nut ! by then it must have a tremendous contribute to human being !!!!