Page 541 - IJB-10-3

International Journal of Bioprinting Engineered 3D-printed PVA vascular grafts

internal section of the PVA grafts during a flow test conducted under simulated body conditions (vacuum and blood
pressure: 40 mbar). The flow was induced by a vacuum pump connected to the outlet of the platform, while the inlet
was connected to a feeding glass. In summation, we have established a suitable protocol for producing small vascular
grafts and demonstrated that the optimization process could significantly affect graft properties.

Keywords: 3D printing; Poly(vinyl alcohol); Channel; Crosslinking; Vascular graft; Small vein

1. Introduction owing to their compatibility (similar to PTFE-Dacron),
thromboresistance (e.g., to thrombotic occlusion or
Cardiovascular diseases have been one of the main causes anastomotic intimal hyperplasia), 21,22 and ability to
of death around the world for decades. By 2030, the global promote tissue growth inside and around the grafts.
annual mortality is predicted to increase to 23.3 million. However, their clinical use is limited by low biostability.
1,2
22
Demand for artificial blood vessels is increasing due to the The low patency of most synthetic grafts in small-diameter
growing incidence of vascular diseases, including occlusive vessel reconstruction is caused by reduced blood flow
vascular disease (coronary heart disease, peripheral velocity, leading to thrombosis. Hence, there is a need
23
arterial disease, critical atherosclerotic narrowing, rupture for alternative grafts to offer innovative solutions for
of the vascular walls, etc.) or different types of cancer. small-diameter vessel replacement. Tissue engineering
3–6
7,8
Despite the use of pharmacotherapy like vasodilators or is an interdisciplinary alternative approach to designing
anticoagulants, surgical repair remains an indispensable grafts that meet clinical requirements. Tissue-engineered
treatment option for patients with severe vascular diseases. vascular grafts have been developed using acellular bovine
9
In this context, artificial blood vessels, serving as vascular and human tissue to construct a vessel-like structure. 24–26
grafts, are essential for surgical repair.
However, collagen-based grafts exhibit inadequate
Their principle of artificial blood vessel development mechanical properties, necessitating the use of an external
is conceptually simple and clinically attractive. In the mesh. The mechanical properties of grafts are extremely
current global vascular grafts market, artificial vascular important, as biomaterial-based vascular grafts should
grafts are widely employed, especially for larger diameter support blood flow and maintain the featured structure
requirements. These advanced grafts play crucial roles in physiological conditions. The vascular graft should
in diverse medical scenarios, including facilitating display both elasticity and fatigue resistance, among other
hemodialysis blood access, addressing vascular properties. 27,28 For very small vessels, grafts must undergo
trauma, managing aneurysms, and contributing to permeability testing, with the fabrication process ensuring
cardiovascular reconstruction. 10,11 the formation of porous walls to sustain permeability. 29–32
These requirements often contribute to the failure of many
However, this approach has proven to be a significant
challenge. 12,13 The history of vascular interventions biomaterial-based vascular grafts. Additionally, an ideal
vascular graft should possess anti-thrombogenic features.
began with early advancements in suturing and vessel
replacement, with pioneers like Carrel and Goyanes Poly(vinyl alcohol) (PVA) is a biodegradable synthetic
demonstrating the feasibility of arteriovenous anastomoses polymer that features high biocompatibility, controlled
and paving the way for modern vascular treatment. 14–16 water solubility, excellent charge storage ability, and
The commonly used revascularization techniques nontoxicity, making it suitable for biomedical applications.
include stent replacement, angioplasty, or bypass graft In the pharmaceutical field, PVA is widely used for preparing
surgery. The autograft vessel approach is a preferred solid dispersions aimed at enhancing drug solubility. 33,34
vascular technique for coronary artery bypass grafts but is Other applications of PVA include the preparation of
inadequate and unsuitable for one-third of patients. 17,18 The hydrogels, 35–39 sponges/meshes, 40,41 electrospun fibers, 42–44
commonly used and most efficient grafts are composed films with high optical quality, and membranes.
46
45
of non-biodegradable polymers, including poly(ethylene PVA hydrogels have been extensively researched over
terephthalate) (PET), poly(tetrafluoroethylene) (PTFE), the years in various blends, owing to their excellent
and expanded PTFE. These grafts are effective for large flexibility, biocompatibility, and versatility. A synthetic
38
vessel replacement (>6 mm internal diameter), but lowly small-diameter vascular graft was developed through
effective for small-diameter replacement (<5 mm internal the combination of PVA hydrogel with low-molecular-
diameter). 5,19,20 Polyurethanes, a non-biodegradable weight (low M ) dextran, along with the incorporation
w
polymer class, are also used for small vessel replacement, of mesenchymal stem cells. 47–50 However, the mechanical

Volume 10 Issue 3 (2024) 533 doi: 10.36922/ijb.2193