![]() Several reviews have already been published that discuss about different methods for tissue engineering of vascular grafts, design of natural and artificial arteries as well as vascular networks, and application of stem cell and other human cells for tissue engineering of blood vessels. Extensive research has been conducted on TEVG over the past few decades, and as a result significant progress has been made in terms of achieving the remodeling of the tissue in the TEHV constructs similar to the native blood vessels, as depicted in Figure 1. In tissue engineering, it is anticipated that cells produce extracellular matrix (ECM) while the polymer is degraded gradually creating the intended tissue. In this approach cells are seeded or encapsulated in scaffolds fabricated from a biodegradable polymer. Tissue engineering is an alternative approach for creating new vascular grafts. This rejection arises from the associated re-occlusion problem caused by thrombosis, aneurysm, and intimal hyperplasia due to mismatch of compliance (compliance is opposite of the stiffness, measured as the strain/expansion or contraction of the graft with force). Synthetic prosthetic grafts are rejected within a few months by the immune system of the body if the diameter of the vessel is smaller than 6 mm. Other issues include poor control over physical and mechanical properties, inflammation and calcification. As an example, a bovine or porcine graft may last for up to fifteen years, which is a major issue for pediatric patients, which will require a new implant replacement at every ten to fifteen years interval. Xenografts suffer from their relatively shorter life span. Besides, there are concerns about their long-term functionality due to the use of strong detergents and decellularizing agents. The use of autografts and allografts are limited due to the lack of tissue donors, previous harvesting or anatomical variability. bovine or porcine pulmonary valve conduit), artificial prostheses or synthetic vascular grafts made of expanded polytetrafluroethylene (ePTFE) and polyethylene terephthalate (PET). coronary artery bypass graft with autologous mammary arteries and saphenous veins), allografts (donor/cadaveric), xenografts (e.g. The currently available options for these transplants are autologous grafts (e.g. Similarly coronary artery diseases and peripheral vascular diseases very often require the replacement of diseased and damaged native blood vessels. In “Fontan Operations”, an engineered blood vessel is required to connect the right pulmonary artery with the inferior vena cava so that the deoxygenated blood can bypass the heart and travel straight to the lungs. In blue baby syndrome, only one of the two ventricles of an infant functions properly, and a “Fontan Operation” becomes necessary. Eventually, cardiac and peripheral bypass surgeries become necessary, requiring replacement of a segment of blood vessels. Atherosclerosis is one of fatal diseases that causes build-up of plaques under the intimal layer, reducing the cross-sectional area available for blood flow and thereby resulting in decreased flow of blood to the tissues downstream to the plaque. Particularly, the pathologies affecting small and medium sized blood vessels are the primary cause of death. The available options for replacement of vascular grafts have limited clinical success with a cost of more than US$25 billion. Each year 1.4 million patients in US need arterial prostheses. ![]()
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