1. Stem cells and cloning: Future challenge
BCMB 465 -Stem Cells & Cloning
Stem cells and cloning: Future challenge
Stem cells are multi-, pleuri- or totipotent
Stem cell derivation: from embryos, from germ cells or from tissues
Cloning of mammals is fraught with problems and, generally, does not work
outlook for “therapeutic” cloning far better than that for “reproductive” cloning

2. Embryonic stem cells Derived from pre-implantation embryo
Have ability to be maintained without differentiating, but: how long???
Appear to have developmental potential to form all kinds of tissues, but: how is this controlled???

3. Embryonic Stem Cells Bone, Skin, Muscle, Nerves, etc. Embryo
growing on irradiated
Mouse Embryo Fibroblasts
Differentiation directed by growth and differentiation factors (now unknown )
Bone, Skin, Muscle, Nerves, etc.

4. Major Goals in Developing Transplantation Therapies from Human ES Cell Lines
Human ES cells
Establish pure cultures of specific cell types
Test physiologic function
Test methods to
prevent rejection
Demonstrate efficacy
Demonstrate safety
Human Trials

5. Basic strategy for cloning of organisms
Remove oocyte nucleus (what epigenetic information is lost?)
Replace with nucleus of somatic cell of individual to be cloned (can somatic nucleus be “reprogrammed” to gametic state?)
Activate development (can somatic nucleus support development in entirety? Or has it lost totipotency?)
Transfer blastocyst to uterus of surrogate mother

6. Survival curve: Cloned embryos

7. “Therapeutic” cloning: Derivation of embryonic stem cells from the patient
Solter and Gearhart, Science 1999

8. Bush stem cell policy
Federal government will fund research on human embryonic stem cells
However, only stem cell lines derived before 9 August 2001 may be used
60 lines asserted to be available
much question and controversy about availability and utility of the 60 lines

9. Stem cell policies around the world
No human embryo research permitted
Germany, France, Switzerland, Norway, Ireland, Austria, Poland, Brazil
Use of already-derived stem cells permitted, but not the derivation US
Both derivation and use of stem cells from spare embryos permitted
Japan, Canada, Spain, Italy, Finland, Sweden, Israel, Singapore, Australia
Derivation and use of stem cells from embryos created for research permitted
United Kingdom, privately funded researchers in the US, de facto policy in China