Cell-Based Therapy

Question 1

Define Regenerative Medicine

Answer 1

Regeneration via small molecule drugs, biological therapies, medical devices or cells and genes

Aims to replace, repair or regenerate human cells to restore normal function

Question 2

Describe the difference between autologous and allogenic transplantation

Answer 2

Autologus = Donor cells are from the same recipient

Allogenic = donor cells are given to different recipient

Question 3

Describe 4 ways in which Cell and Gene Therapy may work in a patient.

Answer 3

1. Host cells spared by disease -> in vitro expansion ->t ransplant
2. Donor cells -> in vitro expansion -> transplant
3. In vivo gene-therapy with viral vector
4. Disease cell taken from host ->ex-vivo gene therapy with viral vector -> In vitro expansion -> transplant

Question 4

Differentiate between Stem cells, progenitor cells and Somatic cells

Answer 4

*Can proligerate

Question 5

Stem cells are able to _____-_____ and _____ into diverse cell types. There is a _____ _____ of differntiation types as stem cells differentiate. Stem cells start as _____ then differentiate into _____, then multipotent and finally unipotent. There is much work on re-programming _____ back into _____ then differentiate these into multipotent cells to repair/replace cells.

Answer 5

Stem cells are able to self-renew and differentiate into diverse cell types. There is a unidirectional reduction of differntiation types as stem cells differentiate. Stem cells start as totipotent then differentiate into pluripotent, then multipotent and finally unipotent. There is much work on re-programming unipotent cells back into pluripotent cells, then differentiate these into multipotent cells to repair/replace cells.

Question 6

Currently, cell therapy clinical trials are performed with neonatal stam cells or progenitor cells from donor tissue. Trials are now shifting towards cell therapy that uses what two cell types?

Answer 6

Embryonic stem cells

Re-programmed induced pluripotent stem cells (iPSCs)

Question 7

Embryonic stem cells (ESCs) can differentiate into any tissue but present three key problems, which are:

Answer 7

1. Derived from embryo, therefore can lead to immune rejection
2. Difficult to induce desired cell type
3. Small fraction remain undifferentiated, continue to proliferate and lead to teratomas

Question 8

Briefly describe how Yamanaka et al, Cell 2006, developed iPSC-MSCs

Answer 8

Somatic cells given 4 reprogramming transcription factors (Oct4, Sox2, Nanog, Lin28) - this reprogrammed the cell into iPSC

iPSC differentiated into MSC via growth factors (bFGF, EGF, PDGF)

Question 9

What are mesenchymal stromal cells and where can they be found?

Answer 9

Multipotent stem cells mainly from bone marrow (can be found in blood, lungs, fallopian tube)

Question 10

Describe three limitations of the use of Mesenchymal Stromal Cells (MSCs)

Answer 10

1. Limited number - needs ex vivo expansion
2. Expansion leads to senescence
3. Genetic instability

Question 11

Describe the advantage and disadvantage of the use of induced pluripotent stem cells (iPSCs)

Answer 11

Advantage: Uses autologous iPSCs so no immunological issue

Disdvantage: Does not negate the risk of tumour generation

Question 12

Describe the advantages of using iPSC-MSCs (3)

Answer 12

1. ↑capacity for proliferation and differentiation
2. ↓senescence
3. Unlimited and personalised source

• Effects have been demonstrated in* ex vivo studies:
• Limb ischamia*

↓NK cytolytic machinery

Alleviating allergic airway inflammation

↓cigarette smoke induced emphysema

Question 13

Briefly describe the 3 main hypothesis for the mechanism of action of MSC cell therapy

Answer 13

1. Replace damaged cells (directly differentiating into lung cells)
2. Paracrine regulation (immunoregulatory effects to modify cells/tissue in the area)
3. Mitochondrial transfer (transfer from MSC into damaged cell)

Question 14

With regards to mitochondrial transfer, what forms to aid the transfer between the cells?

How could mitochondrial transfer be giving benefits in disease?

Answer 14

Tunneling nanotubules (TNTs)

Mitochondria improves cell bioenergetics

TNTs also allow for the transfer of other molecules and organelles

Question 15

Describe the proposed mechanism of mitochondrial transfer through tunneling nanotubes (TNTs)

Answer 15

TNTs form between MSC and epithelial cell

Miro-1 loads MSC mitochnodria on KIF5 using accessory protein Milton/Trak.

KIF% moves along microtubles in the TNTs

Sheng ZH et al, Nat Rev Neurosci

Question 16

Apart from contractile function, what other function do Airway Smooth Muscle Cells (ASMCs) have? How does this affect disease such as COPD

Answer 16

ASMCs = contractile and synthetic

Cytokines, chemokines, adhesion molecules, GF

Could increase inflammation and contribute to the chronic phenotype of COPD