Accelerating in situ endothelialisation of cardiovascular bypass grafts

Abstract

The patency of synthetic cardiovascular grafts in the long run is synonymous with their ability to inhibit the processes of intimal hyperplasia, thrombosis and calcification. In the human body, the endothelium of blood vessels exhibits characteristics that inhibit such processes. As such it is not surprising that research in tissue engineering is directed towards replicating the functionality of the natural endothelium in cardiovascular grafts. This can be done either by seeding the endothelium within the lumen of the grafts prior to implantation or by designing the graft such that in situ endothelialisation takes place after implantation. Due to certain difficulties identified with in vitro endothelialisation, in situ endothelialisation, which will be the focus of this article, has garnered interest in the last years. To promote in situ endothelialisation, the following aspects can be taken into account: (1) Endothelial progenital cell mobilization, adhesion and proliferation; (2) Regulating differentiation of progenitor cells to mature endothelium; (3) Preventing thrombogenesis and inflammation during endothelialisation. This article aims to review and compile recent developments to promote the in situ endothelialisation of cardiovascular grafts and subsequently improve their patency, which can also have widespread implications in the field of tissue engineering.

Figure 1

Shows the different functions of endothelium.

Figure 2

Shows an example of how anti-cd34 antibodies can be immobilized on a polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) surface. Anti-CD34 antibodies were conjugated with amine-functionalized fumed silica onto POSS-PCU using an N-ethyl-N'-(3-(dimethylamino)propyl)carbodiimide-N-hydroxysuccinimide (EDC-NHS) linker. Reproduced form [50] with permission from Tan et al., copyright 2013.

Figure 3

Illustration of method developed by Shin et al. [90] to coat PLCL film with PDAM, and mechanism of PDAM capture of VEGF onto the surface. Reproduced from [90] with permission from American Chemical Society, copyright 2012.

Figure 4

Summarizes the basic principles of photolithography and electron beam lithography [118]. Reproduced form [118] with permission from Elsevier, copyright 2014.