1. Human stem cells The perspective of a Catholic physician-scientist Jose C. Florez MD, PhD Massachusetts General Hospital Harvard Medical School

3. Outline Intro on human development What are stem cells? What can stem cells be used for? How do we obtain stem cells? What is a human embryo? How should we treat a human embryo? Alternatives

4. Fertilization Sperm & eggEmbryo

5. The embryo’s journey

6. Implantation

8. What are stem cells?

9. Copyright ©2005 American Physiological Society Wobus, A. M. et al. Physiol. Rev. 85: 635-678 2005 Stages of development

10. Copyright ©2005 American Physiological Society Wobus, A. M. et al. Physiol. Rev. 85: 635-678 2005 Stem cells can become different tissues

11. Mayhall, Paffett-Lugassy and Zon, Curr Opinion Cell Biol 16 (2004) 713-720 The promise

13. Adult stem cells

14. [Adapted from NIH Guide on Stem Cells: Scientific Promise and Future, 2001 Terese Winslow–medical illustrator ©2001, Terese Winslow.]

15. Korbling, M. et al. N Engl J Med 2003;349:570-582 Possible Roles of Adult Stem Cells in Tissue Repair

16. Korbling, M. et al. N Engl J Med 2003;349:570-582

17. Just recently published

18. So where do we get stem cells from? From adult tissues From the umbilical cord of newborns From healthy fetuses From embryos

19. Copyright ©2005 American Physiological Society Wobus, A. M. et al. Physiol. Rev. 85: 635-678 2005 From an embryo…From a fetus…

20. Korbling, M. et al. N Engl J Med 2003;349:570-582 How do you get an embryo?

21. Mayhall, Paffett-Lugassy and Zon, Curr Opinion Cell Biol 16 (2004) 713-720 You can make one through human cloning (aka nuclear transfer)

22. Steinbrook, R. N Engl J Med 2006;354:324-326 Retrieval of Oocytes

23. Snyder, E. Y. et al. N Engl J Med 2006;354:321-324 Somatic-Cell Nuclear Transfer

24. Copyright ©2005 American Physiological Society Wobus, A. M. et al. Physiol. Rev. 85: 635-678 2005 Human cloning Human cloning generates a much younger copy of oneself Usually defective But viable

25. Hochedlinger, K. et al. N Engl J Med 2003;349:275-286 Reproductive Cloning and Therapeutic Cloning

26. Is reproductive cloning possible? Dolly the sheep

27. Hochedlinger, K. et al. N Engl J Med 2003;349:275-286 Reproductive cloning generates defective adults: most scientists agree on moratorium

28. Landry and Zucker, J. Clin. Invest. 114:1184-1186 (2004) The problem To harvest embryonic stem cells, the embryo must be destroyed

29. What is an embryo? It’s alive It’s human It’s an individual, separate and distinct from the mother Therefore, he/she is a member of our species Homo sapiens We were all embryos once…

30. But it’s so small! Just a cell… Human beings are defined by what they are, not by what they can do Is a mentally retarded person less human? Is a patient with a stroke or dementia less human? Humanity goes beyond skills and abilities An enlightened society protects its weakest members

31. How should we treat a living member of our species? We do not take an innocent person’s life We do not perform surgery on another human being without his/her consent We do not force him/her to donate organs

32. But the benefits are so great… The end does not justify the means The intentions are good, the goal is good, the result is good; but if the action itself is bad, then the entire procedure is unethical We could save many people by forcing a single person to donate both kidneys, heart, liver, lungs, pancreas, corneas…

33. But the embryos are frozen and are going to die anyway… So are people on death row… Should we take their organs?

34. Solter, D. N Engl J Med 2005;353:2321-2323 Derivation of Mouse Embryonic Stem Cells from an Eight-Cell Embryo A ray of hope: Scientists’ attempts to remain within ethical boundaries Harvesting? Defective? Embryo?

35. It has recently been done to human embryos (in our own back yard) Human embryonic stem cell lines derived from single blastomeres Irina Klimanskaya, Young Chung, Sandy Becker, Shi-Jiang Lu and Robert Lanza Nature, doi:10.1038/nature05142

36. Solter, D. N Engl J Med 2005;353:2321-2323 Derivation of Mouse Embryonic Stem Cells from Blastocysts That are Rendered Incapable of Full Development “Not an embryo” or a diseased embryo?

37. Copyright ©2006 AlphaMed Press Gruen, L. et al. Stem Cells 006;24:2162-2169 Summary of approaches to generate human embryonic stem cells

38. Countries where embryonic stem cells are being harvested

39. When ethics and research part ways… Dr. Woo-Suk Hwang

40. Alternatives Continue to advance therapeutic uses of adult stem cells Expand existing umbilical cord stem cell banks Research ways to make adult stem cells more versatile Research ways to create stem cells while bypassing the embryo stage Work with existing embryonic stem cell lines Explore ways of making animal stem cells amenable to implantation in humans

41. Conclusions The Church is not opposed to research; it’s opposed to unethical research We must protect the most vulnerable There is no scientific argument that proves that the embryo is not a live member of our species There are ways to generate stem cells without destroying human embryos We must be kept informed We must defend the culture of life

42. Thank you “Do not wait for leaders; do it alone, person to person.” “Do not wait for leaders; do it alone, person to person.”