Vascular Tissue Engineering: Recent Advances in Small Diameter Blood Vessel Regeneration
Table 4
Studies of the scientific literature (2008–2013) on TEVGs fabricated with natural polymers.
Material
Fabrication method
ID
Mechanical properties
Biological in vitro results
Biological in vivo results
Reference
Fibrin
Two-layer grafts: SMCs embedded in fibrin hydrogel + fibrin layer composed of high concentration fibrinogen
4 mm
After 2 weekstwo layers UTS ~ 90* kPa, BP = 177 ± 5.3 mmHg;
single layer UTS ~ 65* kPa, BP = 18 ± 7.7 mmHg; UTS calculated from circumferential tensile tests
SMCs isolated from 3-day-old lambs;
histological analysis after 2 weeks of culture: SMCs distributed uniformly in the inner layer, SMCs did not migrate into the outer fibrin layer, and SMCs maintained their contractile properties inside gels
nDF entrapment in fibrin gel + static culture for 2 weeks + dynamic bioreactor culture for 5–7 weeks (stimuli: cyclic stretching + luminal, ablumenal, transmural flows)
2.4 mm
After 7–9 weekscircumferential tensile tests
kPa, UTS ~ 1800* kPa;
axial tensile tests
kPa, UTS ~ 1200* kPa;
ID = 2 mm, BP = 1366 ± 177 mmHg, SRS = 0.19 ± 0.05 N,
~ 4.5*%/100 mmHg;
ID = 4 mm BP = 1542 ± 188 mmHg, SRS = 1.32 ± 0.58 N (with entrapped PLA cuffs),
~ 2.5*%/100 mmHg;
ovine femoral artery BP = 2297 ± 207 mmHg,
~ 3.25*%/100 mmHg
Histological analysis after 7–9 weeks of static + dynamic culture: circumferential collagen fiber alignment, minor residual fibrin in 2 mm grafts, none evident in 4 mm grafts, and nhDFs evenly distributed across the thickness
Electrospinning using a rotating translating mandrel
6 mm
BP = 575.67 ± 17.47 mmHg,
= 3.51 ± 0.42%/100 mmHg;
circumferential tensile testsDR = 5 mm/min: UTS ~ 2.4* N,
%;
DR = 25 mm/min: UTS ~ 1.8* N,
%;
DR = 50 mm/min: UTS ~ 1.2* N,
%
MTT assay (7 days): linear increase of NIH/3T3 viability over time;
SEM images (7 days): NIH/3T3 attached, spread, and grew; cell motility through matrix
Protein adsorption: lower on silk than PTFE;
platelet adhesion and spreading: silk and PTFE relatively nonthrombogenic;
confocal images (overnight incubation): higher HCASMC and HUVEC attachment on silk than PTFE;
Pico Green DNA assay (for 14 days): higher rate of HCASMC and HUVEC proliferation on silk than PTFE
Model: rat (4 weeks); no occlusion, clotting, or ischemia; vascular cell remodeling: confluent endothelium, SMCs migration and proliferation
Electrospinning using a rotational mandrel + dynamic dipping
6 mm
BP = 894.00 ± 24.91 mmHg,
= 3.24 ± 0.58%/100 mmHg;
circumferential tensile testsDR = 5 mm/min UTS = 3.17 ± 0.32 N,
= 58.96 ± 4.07%;
DR = 25 mm/min UTS = 2.76 ± 0.39 N,
= 35.6 ± 2.13%;
DR = 50 mm/min UTS = 2.5 ± 0.12 N,
= 39.04 ± 5.31%
MTT assay (7 days): linear increase of NIH/3T3 viability over time, collagen increase metabolic activity at the early time points;
SEM images (7 days): NIH/3T3 attached, spread, and grew