Stem Cells and Stem Cell Therapy

Question 1

Define a stem cell

Answer 1

An unspecialised cell with the ability to self renew and the capability of differentiating into multiple cell types

Question 2

What are the different types of stem cell?

Answer 2

Embryonic stem cells = totipotent

Adult/somatic stem cells = multipotent

Question 3

Where do embryonic stem cells come from?

Answer 3

The cells of the inner cell mass

Question 4

How are embryonic stem cells amplified?

Answer 4

Prolonged differentiation culture with feeder layer

Question 5

How are embryonic stem cells made into different cell types?

Answer 5

By using different media

Question 6

What are the current clinical uses of embryonic stem cells?

Answer 6

All trials in human medicine but include macular degeneration

Question 7

What are the advantages of embryonic stem cells?

Answer 7

Can generate every cell type
Can grow culture indefinitely
The cells are young (telomere length)

Question 8

What are the disadvantages of embryonic stem cells?

Answer 8

Obtaining embryos is very difficult
Amplification of cells from one embryo take a long time
Can differentiate incorrectly
Formation of teratomas can happen
Ethical issues

Question 9

Where are adult stem cells found?

Answer 9

In post-natal tissues theoretically in every tissue in the body but mainly skin and GIT

Question 10

What are the characteristics of adult stem cells?

Answer 10

Are generally dormant or proliferating slowly in situ and have limited potential as they can only make a small number of cell types

Question 11

How are adult stem cells derived and amplified?

Answer 11

Some are easy to harvest such as those in the skin but others such as brain stem cells are harder to harvest
Amplifying in culture is very difficult as they don’t proliferate very fast or indefinitely

Question 12

What are the advantages of adult stem cells?

Answer 12

Ability to harvest stem cells for an individual reduces rejection
Their more limited potential reduces risks of teratomas or forming the wrong cell type in situ
Few ethical concerns

Question 13

What are the disadvantages of adult stem cells?

Answer 13

Hard to generate enough cells to be useful

Even though the potential is limited still don’t know the conditions to generate all the possible cell types

Question 14

What are the current therapeutic uses of adult stem cells?

Answer 14

Bone marrow transplant, MSC’s tracheal transplant

Question 15

What cells are used to reprogramme somatic cells into embryonic stem cells and what are they then called?

Answer 15

Skin derived fibroblasts reprogrammed into induced pluripotent stem cells (iPS)

Question 16

What are the advantages of using iPS?

Answer 16

Prove easy to amplify
Make all cell types
No ethical concerns

Question 17

What are the disadvantages of using iPS?

Answer 17

Not identical to embryonic stem cells due to gene expression - retain epigenetic profiles of adult tissue cells they are derived from
Shorter telomere length resulting in higher rates of cell death and premature ageing

Question 18

How are stem cells used in equine tendon repair?

Answer 18

Mesenchymal stem cells from bone marrow can form osteoblasts/chondroblasts/adipoblasts/ tendenoblasts/myoblasts
Harvested from individual horse then amplified and differentiated into tendenoblasts and then injected into damaged tendon

Question 19

How are stem cells used for bone/cartilage/tendon repair?

Answer 19

Use mesenchymal stem cells from adipose tissue as easier to access but have fewer MSCs

Question 20

What are the side effects of stem cell use?

Answer 20

Little evidence of inappropriate differentiation where the cells have been pre-differentiated
Some swelling at the injection site that is reversible

Question 21

What is the future for stem cell therapy?

Answer 21

Umbilical cord blood is being stored for animals in the same way as humans
Cells in these have the potential to be useful in blood diseases such as leukaemia
Cells in the cord may also be totipotent
Research being conducted into diabetes, CVS and others