8: Repair and Regeneration

Question 1

3 groups in which cells can be divided based on their potential for renewal

Answer 1

1. Labile cells
   - good capacity to regenerate
   - surface epithelial cells
2. Stable cells
   - divide v slowly
   - still retain the capacity to regenerate
   - hepatocytes; renal TUBULAR cells
3. Permanent cells
   - have no effective regeneration
   - nerve cells
   - striated muscle cells

Question 2

Function of Stem Cells

Answer 2

Replacing cells lost through injury OR normal senescence (Labile and Stable populations)

Question 3

Fate of a Stem Cell

Answer 3

Divides into two daughter cells; one differentiates to replace the missing cell; second retains characteristics of a stem cell

Question 4

Number of Stem Cells in each tissue

Answer 4

They’re a minority population

Question 5

Location of Epidermal Stem cells

Answer 5

1. Basal layer (adjacent to Basement Membrane)
2. Sebaceous Glands
3. Hair follicles

Question 6

Where is a separate pool of Stem Cells found in the body

Answer 6

In the bone marrow.

These hematopoietic stem cells can seed into other organs and differentiate into the required tissue.

Question 7

How to stem cells influence ability to regenerate

Answer 7

Ability to regenerate depends on INTEGRITY of stem cell population

Question 8

What affects integrity of stem cell population

Answer 8

1.Ionising Radiation
–>impairs regenerative ability of stem cell
OR
–>propagates mutations to daughter cells w risk of neoplastic transformation

Question 9

what are the initiating chemical/cellular factors for healing and repair of skin that trigger the release of subsequent cytokines

Answer 9

1. Hypoxia

2. Growth Factors released from Platelet Degranulation

Question 10

what stimulates keratinocyte PROLIFERATION and MOBILITY

Answer 10

Keratinocyte Growth Factor (KGF) AND Epidermal Growth Factor (EGF) released by:
platelets
dermal FIBROBLASTS
macrophages

Question 11

What growth factor induces angiogenesis

Answer 11

VEGF (Vascular Endothelial Growth Factor) released by:
Keratinocytes
Macrophages

Question 12

What triggers accumulation and activation of macrophages; PROLIFERATION of fibroblasts and MATRIX production

Answer 12

PDGF (Platelet-derived Growth Factors)

Question 13

What controls MYOFIBROBLASTS and partly influences collagen formation

Answer 13

TGF-beta (Transforming Growth Factor-beta)