Tissue Regen & Stem Cells Week 9

Question 1

Properties of stem cells

Answer 1

• reproduces itself
• can differentiate into at least 2 different kinds of specialised cell
• can give rise to multiple specialised and functional cell types

Question 2

Special features of stem cells?

Answer 2

• potential to generate and replace cells/tissue that have been damaged or destroyed
• immortal, can duplicate over and over
• so may be useful to cure diseased organs/tissues

Question 3

Potential therapeutic applications of stem cells

Answer 3

= 1X10^11 blood cells newly formed every day

• many million skin cells turned over (skin replaced within 14 days)
• new muscle fibres are generated during exercise periods
• wound healing
• brain cells are replaces in the olfactory system and hippocampus

Question 4

Embryonic stem cell define

Answer 4

Derived from early blastocyst and are able to generate almost every cell type of the body (pluripotent)

Question 5

Adult stem cell define

Answer 5

Derived from the adult organs and are capable of generating some cells of the body (multipotent)

Question 6

Stages from the oocyte to blastocyst

Answer 6

Ovulation 
Oocyte
DAY 0 = Fertilisation
Fertilised egg (zygote)
DAY 1 = First cleavage
DAY 2  = 2 cell stage, 4 cell stage
DAY 3-4 = 8 cell uncompacted morula
DAY 5 = early blastocyst with inner cell mass/blastocoel/trophectoderm
DAY 6-7 =  Zona pellucida, late stage blastocyst (hatching)
Day 8-9 = Implantation of the blastocyst (epiblast + hypoblast)

Question 7

How to derive embryonic stem cells? (STAGES)

Answer 7

• In vitro Fertilised egg
• Blastocyst Stage (5-7 days old)
• Inner Stem cell Mass
• Cultured Undifferentiated Stem Cells
• Specialised Cells (blood, neural, muscle)

Question 8

Embryonic Stem Cell Propagation

Answer 8

• Initial Development (fertilised egg will grow for 5 days and form a blastocyst)
• Extraction (stem cell extracted and placed into nutrient bath)
• Propagation (Become Stem cells stay stable and replicate proteins that inhibit specialisation OR without inhibitor proteins they differentiate into particular types of cells)

Question 9

Successful treatment of animal models of diseases with specialised cells from ES cells

Answer 9

• severe immune deficiencies
• diabetes
• SCI
• demyelination (MS)
• neurodegenerative diseases (Parkison’s)
• MI

Question 10

Embryonic Stem Cells SUMMARY

Answer 10

• developmentally transient as only generated from 5-7 day old blastocysts
• function lies in development
• unlimited number of symmetric divisions
• pluripotent
• can colonize germ line giving rise to eggs/sperms
• clonogenic properties = single cell can give rise to a colony of genetically identical cells/clones/same properties
• express specific markers = Oct-4, AP, SSEA-4
• grown on feeder layers so still risk of viral infection but new methods available to grow without feeder layer
• clear separation of animal cells and human not solved
• unlimited proliferation after transplant risky = cancerous growth
• ES cells are a cell culture artifact as no biological equivalent?
• no natural role for them in regeneration
• biological progentiors of adult stem cells
• ethically controversial
• hope that will be used in clinical applications

Question 11

Barriers to ES use

Answer 11

• give rise to teratomas after transplantation

- immune rejection in ES stem cell based therapies

Question 12

Teratomas

Answer 12

• benign cancer
• ## no axis formation or segmentation so don’t resemble embryos

Question 13

Immune Reection

Answer 13

• recognised as foreign by host immune system so destroyed via GVHD

Question 14

SCNT

Answer 14

Dolly the Sheep

• replace nuceli of egg cells with nuceli from differentiated cells
• to clone

Question 15

Induced Pluripotent Stem Cells

Answer 15

• directly generated from adult cells
• reprogramme adult cells to become pluripotent via introduction of 4 specific transcription factors
• autologous cells so less risk of immune rejection
• IPS

Question 16

Issues concerning nuclear transfer

Answer 16

• how severe will immune reection be
• other solutions exist
• is it practical? where will unfertilised eggs come from?
• is it safe?
• is it efficient? how many eggs do you need for 1 successful nucelar transfer

Question 17

Arguments in favor of embyronic stem cell research (ESCR)

Answer 17

• ESC research fulfills the ethical obligation to alleviate human suffering
• IVF embryos are discarded so better for them to be of value for research
• produces cells in a petri dish not a pregnancy

Question 18

Arguments against ESCR

Answer 18

• stem cells taken from human blastocyst which equals to terminating a potential life
• risk of commerical exploitation of human beings
• slippery slope argument as research will lead to reproductive cloning

Question 19

Religious positions concerning ESC

Answer 19

• research/use of early embryos is not immoral (Islamic, Synod Protestant if occurs before implant egg into uterus
• using human ESC is immoral (Catholic & Greek Orthodox Churches)
• life saving research is a moral obligation

Question 20

Concept of Tissue Engineering

Answer 20

• combining cells with material under conditions leading to tissue formation
• combine a scaffold with cells for tissue replacement & repair
• to proliferate/differentiate stem cells and progenitors in controlled/efficient/reproducible manner to end up with terminally differentiated tissue structures

Question 21

Concept of Regenerative Medicine

Answer 21

• learn from mechanisms already used
• study stem cells in natural environment in animal model systems/cell culture
• translate derived knowledge into technologies and treatments to cure major diseases of mankind