L11 - Vascularisation Flashcards
In TE constructs what does vascularisation do?
- Avoids graft necrosis
- Generates thicker tissues
- Helps innervation
- Improves graft function
What is vasculogenesis?
De novo b.v. formation from progenitor cells
Mesoderm - hemangioblasts - tube formation - primary cap plexus
What is angiogenesis?
New blood vessel formation via extension/remodelling of existing blood vessels. Driven by hypoxia - release of VEGF - MMP breaks down BM - endo cells create vasc sprouts that move toward source of VEGF - recruitment of smooth muscle and pericytes
Can be physiological (period) or pathological (tumour angiogenesis)
What are the important factors involved in angiogenesis?
VEGF, hypoxia inducible factor, PDGF, angiopoietin, MMPs
What is arteriogenesis?
Maturation of blood vessels via increase in the fluid sheer stress e.g. due to occlusion. Endo cells release GFs - prolif of endo and smooth muscle cells
What are the approaches for vascularisation?
Scaffold design - porous scaffold
Scaffold functionalisation - GF delivery, controlled release is crucial
Explain the study - Polymeric system for GF delivery
VEGF - initiate angio but can’t promote maturation
PDGF - promotes maturation
HYPOTHESIS - dual delivery - formation of mature vasculature
2-stage relase:
1. VEGF mixed with scaffold polymer - stim growth
2. PDGF encap in microspheres to facilitate maturation
SLOW - may not be quick enough to prevent necrosis
Prevascularisation strategies
In vitro
- TE cultured in vitro to build prevasc structures
- Network can connect with exisiting bv in tissues
Prevascularisation strategies
In vivo
- Implant in easy access, well vasc site - after connections have been made, TP to damaged site
- Can be in muscle flap - take flap with TE construct
- AV loop - spontaneous sprouting of vessels. No need to embed in muscle
