Skin Tissue Engineering Flashcards
(36 cards)
Describe the structure of the epidermis.
Keratinised stratified squamous epithelium with predominantly keratinocytes but also melanocytes and dendritic cells. The keratinocytes differentiate as they move away from the basement membrane until they reach terminal differentiation and die on the skin surface.
Avascular and relies on nutrient supply from below.
Describe the structure of the dermis.
Houses the sweat glands, hair follicles, smooth muscles, sensory
neurons, and blood vessels.
The upper layer is thin (loose connective tissue- collagen and elastin)
The deeper layer is thicker (dense connective tissue - collagen fibre bundles)
Describe the structure of the hypodermis.
Composed of loose connective tissue and adipose tissue, and highly vascular.
How are burns classified?
By depth:
1st degree: epidermis only
2nd degree: dermis involvement (blisters)
3rd degree: into hypodermis, requires treatment
Describe wound healing in skin and tell me the cell types involved in each stage:
- Haemostasis: Platelet activation to form fibrin clot. Releases inflammatory cytokines to attract immune cells.
- Inflammation: Infiltration of neutrophils then M1 macrophages to kill any foreign bodies.
- Proliferation: Recruitment of fibroblasts and endothelial cells for rapid granulation tissue formation. M2 macrophage modulation.
- Remodelling: Remodelling of tissue, controlled by MMPs and TIMPs.
What are the goals of skin repair?
Restore barrier
Maintain fluid balance
Prevent infection
Preserve movement and sensation
Maintain aesthetics.
What is the gold standard for skin replacement?
Autologous skin grafts.
What are the two types of autologous skin grafts?
Split thickness (all epidermis + small section of dermis)
Full-thickness (all epidermis + all dermis)
What are the pros and cons of split-thickness skin grafts?
+ Survive on poorly vascularised wounds
– More prone to contraction
How do full-thickness grafts compare to split-thickness?
+ They retain more natural characteristics
+ Resist contraction
- Need well-vascularised beds.
- Limited to small wound sites
What causes skin graft contraction, and how is it managed?
Contracture due to myofibroblast activity; managed with pressure garments or further surgery.
What are CEAs?
Cultured sheets of autologous keratinocytes used to resurface skin wounds.
What are the drawbacks of CEAs?
Fragile, slow to prepare (9–12 days), difficult timing, reagent contamination risk.
What is mySkin, and how does it differ from CEAs?
A thin silicone membrane seeded with autologous keratinocytes that improves delivery and handling over CEAs.
How does plasma polymerisation improve mySkin?
It adds acid groups to the silicone to enhance keratinocyte adhesion.
What are the clinical benefits of mySkin?
Flexible timing, robust handling, weekly application.
What are the limitations of mySkin?
Expensive, requires clean room, slow adoption by clinicians.
What is a chronic wound?
A wound that fails to heal within 6 weeks despite standard care.
What factors contribute to chronic wounds?
Poor vasculature, infection, diabetes, immobility, inflammation
What is an example therapy process for chronic wound management?
- Vascular surgery and/or amputation
- Biotherapy using disinfected fly larvae to clean necrotic tissue
- Honey used as an antimicrobial.
- Cell therapy: mySkin to deliver autologous keratinocytes.
a. Wound bed pre applications of mySkin
b. Subsequent applications of mySKin
What is the tissue engineering approach to skin grafting?
Seeding autologous keratinocytes and fibroblasts on decellularised dermis and culturing at an air-liquid interface.
What strategies can promote angiogenesis?
Pre-vascularised scaffolds
3D printed vascular networks
Pro-angiogenic growth factors
Improving the wound bed health
What is the purpose of dermal regeneration templates?
To allow dermal healing and vascularisation before applying a skin graft.
What are the components of Integra™?
Bovine collagen + shark GAGs with a meshed silicone membrane as a temporary layer.
