1.  Stem Cells

2. Understandings  Specialized tissues can develop by cell differentiation in multicellular organisms.  Differentiation involves the expression of some genes and not others in a cell’s genome.  The capacity of stem cells to divide and differentiate along different pathways is necessary in embryonic development and also makes stem cells suitable for therapeutic uses.

3. International mindedness  Stem cell research has depended on the work of teams of scientists in many countries who share results thereby speeding up the rate of progress. However, national governments are influenced by local, cultural and religious traditions that impact on the work of scientists and the use of stem cells in therapy.

4. Definition  The capacity of cells to divide and differentiate along different pathways is necessary in embryonic development. It also makes stem cells suitable for therapeutic uses.

5. Egg and Sperm  A new animal life  2 gametes = 1 zygote  1 cell divided into 2 = embryo  Further division  But cells have not differintiated

6. Stem Cell Properties Can divide repeatedly  Produce copious quantities of new cells.  Useful for the growth of tissues or the replacement of cells that have been lost or damaged. Not fully differentiated  They can differentiate in different ways, to produce different cell types.

7. Embryonic Stem Cells – Therapeutic  Potentially very useful to:  Regenerate tissue  Means of healing disease  Grow whole replacement organs

8. Embryonic Stem Cells – Non-therapeutic  Produce large quantities of striated muscle fiberes (meat)  In the future – might not need to slaughter cattle

9. Differentiation  During embryo development cells commit to a pattern.  Eventually each cell becomes committed to develop into one specific cell types.  They are no longer stem cells.

10. Some remain  A few remain as stem cells  Present in tissue: bone marrow, skin and liver  Powers of regeneration & repair

11.  Therapeutic Uses

12. Utilization  The use of stem cells in the treatment of disease is mostly at the experimental stage, with the exception of bone marrow stem cells. Scientists, however, anticipate the use of stem cell therapies as a standard method of treating a whole range of diseases in the near future, including heart disease and diabetes.

13. Application  Use of stem cells to treat Stargardt’s disease and one other named condition.

14. Stargardt’s disease  Stargardt’s Macular Dystrophy  Genetic disease  Appears in children ages 6-12  Recessive mutation of gene ABCA4  Membrane protein used for active transport in retina cells malfunctions  Photoreceptive cells in the retina degenerate  These cells detect light so vision worsens  May cause blindness

15. Stargardt’s Disease  Researchers have developed methods for making embryonic stem cells develop into retina cells.  Originally done in mice  Injected cells not rejected  Did not form tumours  Cells moved to the retina, attached and remained  Caused vision improvement  Video Video  November 2010 - FDA approved stem cell research November 2010 - FDA approved stem cell research  Research in England Research in England

16. Trial  Woman in her 50’s  50,000 retina cells derived from embryonic stem cells injected into her eyes  Cells attached to retina  Improvement in vision with no side effects

17.  Another use in disease: Leukemia

18.  Cancer – mutation of genes  Begins to make abnormally large numbers of white blood cells  No tumour forms  Normal range = 4,000 – 11,000 per mm 3 of blood  With leukemia = 30,000 or above

19. Cure Leukemia  Must kill cells in bone marro  Chemotherapy  Destroys stem cells in the bone marrow

20. Stem cells & Leukemia  A large needle inserted into a large bone (pelvis) – fluid removed  Stem cells extracted from the fluid & frozen (adult stem cells therefore can only make blood cells)  High dose of chemotherapy drugs – bone marrow loses its ability to produce blood cells  Stem cells are returned to the patient’s body and re-establish themselves

21. Stem Cell Ethics  Stem cell research is controversial  Old research would be considered unethical today  Patients without their consent  People do not understand the sources of stem cells

22. Application  Ethics of the therapeutic use of stem cells from specially created embryos, from the umbilical cord blood of a new- born baby and from an adult’s own tissues.a new-born baby and from an adult’s own tissues.

23. Sources of Stem Cells Embryos can be deliberately created by fertilizing egg cells (4 – 16 cells) Blood can be extracted from the umbilical cord of newborns (frozen) Stem cells can come from some adult tissues (bone marrow)

24. Embryonic stem cells  Almost unlimited growth potential.  Can differentiate into any type in body.  More risk of becoming tumour cells than adult stem cells  Less chance of genetic damage due to the accumulation of mutations than with adult stem cells  Likely to be genetically different from an adult patient  Kills the embryo

25. Cord Blood Stem Cells  Easily obtained and stored.  Commercial collection & storage services already available.  Fully compatible with the tissues of the adult that grow – no rejection problems occur.  Limited capacity to differentiate into different cell types – only naturally develop into blood  Limited quantities of stem cells from one baby’s cord.  The umbilical cord is discarded whether or not stem cells are taken from it.

26. Adult Stem Cells  Difficult to obtain because there are few and buried deep.  Less growth potential than embryonic stem cells.  Less chance of malignant tumours developing than from embryonic stem cells.  Limited capacity t differentiate into different cell types.  Fully compatible with the adult’s tissues; rejection not a problem.  Removal of stem cells does not kill the adult from which the cells are taken.

27. Aim 8  There are ethical issues involved in stem cell research, whether humans or other animals are used. Use of embryonic stem cells involves the death of early-stage embryos, but if therapeutic cloning is successfully developed the suffering of patients with a wide variety of conditions could be reduced.

28. Final Thoughts  When does human life begin?  in vitro fertilization required hormone treatment to women  Should women be paid for supplying eggs