L4 - bioengineered skin

Question 1

why do we need to engineer skin

Answer 1

for clincal needs:
- burns
- plastic surgery
-scarring
- replacing the skin to prevent further damage like swelling
- chronic wounds

for experimental models
- can develop more treatments based on
- can test the effectiveness of the treatment

Question 2

function of the skin

Answer 2

Protective barrier against the UV,
Thermoregulatory
hormonal - like Vit D
aesthetics

Question 3

3 layers of the skin structure

Answer 3

epidermis - outermost layer
dermis
hypodermis - layer of fat - inner most layer

Question 4

what does the basal layer so

Answer 4

contain stem cells and basal cells which can divide into specialised cells. then they move upwards to the epidermis layer to replace the cells.

Like keratinocytes

Question 5

what does eccrine gland and secaceous gland do

Answer 5

eccrine - produces swear
sebaceous - produces sebum

Question 6

situations where skin need to be replaced

Answer 6

chronic wounds like when there is an ulceration

-recontrsution following a surgery like burns, excision, amputations

Question 7

when there is a wounds, skin can be left to heal. but sometime a graft is better. why?

Answer 7

leaving it to heal will increase the the risk of infection as it may take a long time to heal.

and depending on the site of the wounds, when it heals, the skin will be pulled together to close the wound and it will look weird. So graft is better for cosmetics

Question 8

example of a graft

Answer 8

split skin graft >thin layer of skin from elsewhere.
Composed of epidermis and a superficial part of the dermis

Question 9

ideal characteristics of bioengineered skin

Answer 9

-durable
-semi permeable to wear
-barrier to microbial invasion
-non antigenic
-non toxic
-easy to apply
cosmetically acceptable
painless

Question 10

what are the current skin substitutes

Answer 10

Acellular dermal sub
Autologous epidermal sub
Allogenic epidermical -dermal sub

Question 11

properties of acellular dermal sub

Answer 11

a compostite of consists of a collagen mesh, which acts as a “dermis” and a silicon membrane which acts as an “epidermis

• has no cells in the sub
• can be used to cover the wound short term

Question 12

properties of autologous epidermal sub

Answer 12

has autologous keratinocytes on the membrane with laser drilled pore.

Keratinocytes are derived from the cell culture of the biopsy from the patient

Question 13

properties of allogenic epid-dermal sub

Answer 13

keratinocytes are taken neonatally and incoporated into the membrane alongside collagen and fibroblasts

Question 14

process of tissue regeneration via cell therapy by bone marrow cells

Answer 14

Bone marrow cells > isolate the HSC (hematopoitic stem cells

Question 15

process of tissue regeneration via cell therapy by biopsy

Answer 15

biospy> cell isolation of wanted cells like keratinocytes, fibroblast etc > creates cell cultures on them > (two ways for the next step)

Cell culture> tissue engineering to create a graft of biomaterial> transplantation

or

Cell culture > local application of differentiated cells

Question 16

process of tissue regeneration via cell therapy by iPS

Answer 16

biospy> cell isolation of wanted cells like keratinocytes, fibroblast etc > reprogrammed them using transcrption factors into iPS cells

then genome editing on the iPS cells> in vitro differentiation > used to make the graft

Question 17

problems of bioengineered skin

Answer 17

lack of differentiated cells included in the skin
- reduced vascularization
- scarring
cell therapy
development costs
- can degrade and affect other biological tissues