Stem Cells and Therapeutic Applications
Module 8
Stem cell = single cell that can replicate itself or differen8ate into many cell types
- Will grow in culture indefinitely
To8potent vs pluripotent vs mul8potent stem cells
- Zygote = to8potent stem cell
o Will differen8ate into all the cells
- To8potent à can contribute to extraembryonic 8ssue or differen8ate into any cell
o Could result in an en8re organism
- Pluripotent à can differen8ate into many different cell types but not able to form a
complete organism on their own
- Mul8potent à can differen8ate but more specialized and limited
- Blastula = pluripotent stem cells
o Inner cell mass
o Inner cell mass can be expanded in culture
o Will differen8ate into different cell types
o Disadvantage = not matched to pa8ent
- Invagina8on of blastula = gastrula (mul8potent stem cells)
o Divides into 3 germ layers
§ Ectoderm
§ Mesoderm
§ Endoderm
o Can differen8ate into germ cells
Mul8potent Stem Cells
- Placenta mesenchymal stem cells (from mesoderm lineage)
o Stem cells from cord 8ssue and cord blood from placenta
o Hematopoie8c stem cells à mul8potent not pluripotent
Classical View of Differen8a8on = one way differen8a8on over 8me
- Cannot re-program cells that have gone down a specific differen8a8on route
, Soma8c Cell Nuclear Transplant/Transfer (SCNT)
- Inject nucleus from adult soma8c cell (differenta8ated cell) into an enucleated egg
- Allow development to occur to form blastocyst
o Can make embryonic stem cells, fetus/tadpole or fer8le adult
In humans:
- Removed DNA from human oocyte
- Reprogrammed nuclei from skin cells of 8 month old baby
- Injected nuclei into oocytes
- Successful derived ES cells from blastocysts
*addi8on of a dose of caffeine helps produce cloned human embryos that could provide a
tailor made stem cell line
Therapeu8c Cloning vs reproduc8ve cloning
- Reproduc8ve cloning = genera8on of a new organism
o Dolly the sheep
- Therapeu8c cloning = genera8on of a blastula and
harvesta8on of inner cell mass to harvest stem cells for
treatment of disease
Induced Pluripotent Stem Cells (iPS cells)
- 4 pluripotency factors (transcrip8on factors)
o C-myc (proto-oncogene, TF)
o Oct4 (proto-oncogene, TF)
o KLF4 (kruppel-like factor 4, TF that interacts with
p53 – oncogenic poten8al)
o Sox2 (SRY box 2, TF, stem cell maintenance in
nervous system)
- Allowed for reprogramming of soma8c cells
Issues
- SCNT à
o Source of oocytes
o Can human cells be reprogrammed
o Ethical issues of therapeu8c vs reproduc8ve cloning (eg. To cure mitochondrial
diseases)
- iPS à
o oncogenic poten8al of reprogrammed cells
Module 8
Stem cell = single cell that can replicate itself or differen8ate into many cell types
- Will grow in culture indefinitely
To8potent vs pluripotent vs mul8potent stem cells
- Zygote = to8potent stem cell
o Will differen8ate into all the cells
- To8potent à can contribute to extraembryonic 8ssue or differen8ate into any cell
o Could result in an en8re organism
- Pluripotent à can differen8ate into many different cell types but not able to form a
complete organism on their own
- Mul8potent à can differen8ate but more specialized and limited
- Blastula = pluripotent stem cells
o Inner cell mass
o Inner cell mass can be expanded in culture
o Will differen8ate into different cell types
o Disadvantage = not matched to pa8ent
- Invagina8on of blastula = gastrula (mul8potent stem cells)
o Divides into 3 germ layers
§ Ectoderm
§ Mesoderm
§ Endoderm
o Can differen8ate into germ cells
Mul8potent Stem Cells
- Placenta mesenchymal stem cells (from mesoderm lineage)
o Stem cells from cord 8ssue and cord blood from placenta
o Hematopoie8c stem cells à mul8potent not pluripotent
Classical View of Differen8a8on = one way differen8a8on over 8me
- Cannot re-program cells that have gone down a specific differen8a8on route
, Soma8c Cell Nuclear Transplant/Transfer (SCNT)
- Inject nucleus from adult soma8c cell (differenta8ated cell) into an enucleated egg
- Allow development to occur to form blastocyst
o Can make embryonic stem cells, fetus/tadpole or fer8le adult
In humans:
- Removed DNA from human oocyte
- Reprogrammed nuclei from skin cells of 8 month old baby
- Injected nuclei into oocytes
- Successful derived ES cells from blastocysts
*addi8on of a dose of caffeine helps produce cloned human embryos that could provide a
tailor made stem cell line
Therapeu8c Cloning vs reproduc8ve cloning
- Reproduc8ve cloning = genera8on of a new organism
o Dolly the sheep
- Therapeu8c cloning = genera8on of a blastula and
harvesta8on of inner cell mass to harvest stem cells for
treatment of disease
Induced Pluripotent Stem Cells (iPS cells)
- 4 pluripotency factors (transcrip8on factors)
o C-myc (proto-oncogene, TF)
o Oct4 (proto-oncogene, TF)
o KLF4 (kruppel-like factor 4, TF that interacts with
p53 – oncogenic poten8al)
o Sox2 (SRY box 2, TF, stem cell maintenance in
nervous system)
- Allowed for reprogramming of soma8c cells
Issues
- SCNT à
o Source of oocytes
o Can human cells be reprogrammed
o Ethical issues of therapeu8c vs reproduc8ve cloning (eg. To cure mitochondrial
diseases)
- iPS à
o oncogenic poten8al of reprogrammed cells
