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Stem cell and regenerative medicine
5-9-2016
Why we need stem cells in our body?
In embryo development: to increase cell number
and to differentiate into different cell types.
In adult body: to continuously supply short lived
somatic cells and to replace damaged cells
Stem Cells
• Stem cells have two defining attributes:
– The capacity for self-renewal.
– The ability to differentiate into many
different cell types.
Stem Cells
• Niche of stem cells
Adult stem cells in tissue are thought to
reside in niches
Patterns of stem-cell differentiation.
Transcriptional network regulating pluripotency of
ES cells.
Embryonic stem (ES) cells can be maintained in
culture and can form differentiated cell types.
Embryonic stem cells in the dish
Intestinal stem cells:ｈｏｗ ｔｏ ｉｄｅｎ.
Regeneration of the intestinal epithelium from stem cells can be
demonstrated in pulse-chase experiments.
Three modes of neurogenesis during cortical development. RG in
cortex generate neurons
Neural stem cell niche in the adult brain.
Formation of blood cells from hematopoietic stem
cells in the bone marrow.
The original question:
Do all cells in the body have the same
sets of genes?
Two alternative hypothesis:
or
PNAS 1952 38 (5) 455463
是否發育晚期的細胞核已無法回復全能發育的潛力？
丟失了基因還是不可逆的修飾？
John Gurdon Kt DPhil DSc FRS
Distinguished Group Leader in the Wellcome Trust/CRUK
Gurdon Institute in Cambridge
• 戈登1933年出生。
• 他中學唸的是1440年創校的伊頓公學 (Eton College)。
• 在校成績生物科在250位同級生中名列最後。
• 導師給他的評語是：我想戈登希望未來成為一位科學家，但
從他目前的表現看來，這似乎是個不可能的任務！
• 進牛津大學專攻古典文學，隨後轉到動物系
• 1961年得到動物學的博士學位。
– Studies on nucleocytoplasmic relationships during differentiation in
vertebrates .
• 美國加卅理工學院，作了有關細菌遺傳學的博士後研究。
• 1962年回到英國牛津大學動物系任教，1971轉到劍橋大學任
教迄今。
Why should Gurdon repeat this experiment?
Two technical innovations:
1,用Zenopus的卵 (big size!)
2, 用UV來破壞卵中的染色體和去除外層保護的膠質
Late stage embryonic cell nuclei still can develop an viable frog!
How about a fully differentiate cell nuclei?
完全分化的體細胞仍然擁有完整的遺傳資訊！
Gurdon, J.B. & Uehlinger, V. Nature 210, 1240–1241
(1966)
What is next?
Is somatic cell nuclear transfer
(SCNT) also true for mammalian
animal?
Dolly, 1997
Is Dolly a scientific breakthrough?
What are signals in the cytoplasma of egg
to trigger reprogramming of silenced
genetic program in somatic cell nuclei?
Could we identify cytosolic factors which
can convert a somatic cell nuclei into a
embryonic stem cell with totipotent as
a fertilized egg ？
A mission impossible!
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Shinya Yamanaka
1962年出生.
1987年在 Kobe University 得到MD.
1993在Osaka City University 得到Ph.D.
1993-96 在UCSF作博士後研究
1996 – 99 Osaka City University 助理教授.
1999–2003 Nara Institute of Science and Technology 副
教授.
• 2004 -10 Institute for Frontier Medical Sciences教授
• 現任京都大學教授和 iPS Cell研究與應用中心主任
Identification of ES cell associated
transcripts by digital differential display
To compare expressed sequence (EST) libraries from
mouse ES cells (3 libraries; 33,077 clones) and those
from various somatic tissues (103 libraries; 1,040,493
clones) and to identify genes overrepresented in ES cellderived libraries.
http://www.ncbi.nlm.nih.gov/UniGene
Transgenic fibroblasts with a knock-in gene at the Fbx15 locus.
The knock-in was βgeo: a fusion of LacZ gene and neomycin-R
gene Normally, Fbx15 is highly expressed in ES cells, but not
expressed in fibroblasts
24 genes were selected as candidates to induce pluripotency in somatic cells, For bcatenin, c-Myc, and Stat3, they used active forms, S33Y-b-catenin, T58A-c-Myc and
Stat3-C, respectively. Because of the reported negative effect of Grb2 on pluripotency,
they also included its dominant-negative mutant Grb2DSH2 as 1 of the 24 candidates.
Are they really
pluripotent stem
cells ?
Teratoma
formation and
germ line
differentiation in
vivo
Embryoid body
formation and
differentiation in
vitro
Induction of Pluripotent Stem Cells
from Mouse Embryonic and Adult
Fibroblast Cultures by Defined Factors
Kazutoshi Takahashi and Shinya Yamanaka
Cell 126, 663–676; 2006
Elite vs Stochastic model
Reprogramming occurs in two phases
Stoichiometry of factors is important for reprogramming
Two major application of iPS
Personalized drug screening
Personalized cell therapy
How to directly demonstrate that
the iPS cells is totipotent?
Tetraploid complementation
PS cells produce viable mice through
tetraploid complementation
Nature 461, 86-90 (3 September 2009)
What are the future directions?
1, From 24 to Zero?
2, Virus? Plasmid? Small Molecule?
3, Fibroblasts? Hepatocytes? Blood Cells?
4, Induced Somatic Stem/Progenitor Cells?
A Fresh Look at iPS Cells by Shinya Yamanaka
Cell 137, April 3, 2009 page 13-17
Pluripotent Stem Cells Induced from Mouse Somatic Cells
by Small-Molecule Compounds
Science 341: 651-
VPA,CHIR99021(CHIR), 616452, Forskolin, [3deazaneplanocin A (DZNep)