An Anti-CD34 Antibody-Functionalized Clinical-Grade POSS-PCU Nanocomposite Polymer for Cardiovascular Stent Coating Applications: A Preliminary Assessment of Endothelial Progenitor Cell Capture and Hemocompatibility

Abstract

In situ endothelialization of cardiovascular implants has emerged in recent years as an attractive means of targeting the persistent problems of thrombosis and intimal hyperplasia. This study aimed to investigate the efficacy of immobilizing anti-CD34 antibodies onto a POSS-PCU nanocomposite polymer surface to sequester endothelial progenitor cells (EPCs) from human blood, and to characterize the surface properties and hemocompatibility of this surface. Amine-functionalized fumed silica was used to covalently conjugate anti-CD34 to the polymer surface. Water contact angle, fluorescence microscopy, and scanning electron microscopy were used for surface characterization. Peripheral blood mononuclear cells (PBMCs) were seeded on modified and pristine POSS-PCU polymer films. After 7 days, adhered cells were immunostained for the expression of EPC and endothelial cell markers, and assessed for the formation of EPC colonies. Hemocompatibility was assessed by thromboelastography, and platelet activation and adhesion assays. The number of EPC colonies formed on anti-CD34-coated POSS-PCU surfaces was not significantly higher than that of POSS-PCU (5.0±1.0 vs. 1.7±0.6, p>0.05). However, antibody conjugation significantly improved hemocompatibility, as seen from the prolonged reaction and clotting times, decreased angle and maximum amplitude (p<0.05), as well as decreased platelet adhesion (76.8±7.8 vs. 8.4±0.7, p<0.05) and activation. Here, we demonstrate that POSS-PCU surface immobilized anti-CD34 antibodies selectively captured CD34+ cells from peripheral blood, although only a minority of these were EPCs. Nevertheless, antibody conjugation significantly improves the hemocompatibility of POSS-PCU, and should therefore continue to be explored in combination with other strategies to improve the specificity of EPC capture to promote in situ endothelialization.

Biomimetic modified clinical-grade POSS-PCU nanocomposite polymer for bypass graft applications: A preliminary assessment of endothelial cell adhesion and haemocompatibility

“…This study seeks to explore the concept of further surface modification through biofunctionalisation of POSS-PCU with collagen type I via a simple, reliable and controllable method of TSPT [4]. The complex processes at the interface between the material surfaces when contacting the blood influence the performance of the implant, and can often lead to failure through excessive thrombosis, thus the haemocompatibility mainly depends on the surface properties via contact activation of the biomaterial.…”

“…The average values of three measurements on different points of each of the samples were recorded. Surfaces with WCA measurements of N 90°were considered hydrophobic, whereas those b 90°were considered hydrophilic [4].…”

“…Hence, materials that promote in situ endothelialisation of cardiovascular implants (without IH or thrombus formation during endothelium development) would be highly desirable. In vivo circulating ECs, endothelial progenitor stem cells (EPCs), and the less well-defined CD133 + , CD34 + , and CD45 + progenitor cells could potentially be recruited on to bypass graft materials to enhance in situ endothelialisation [2][3][4].…”

Multifaceted prospects of nanocomposites for cardiovascular grafts and stents

“…In order to circumvent the problems associated with the blood compatibility of bypass grafts, as well as stents and their failure due to lack of mechanical strength and infection, various studies were done incorporating nanocomposites. [17][18][19][20][21][22][23] Despite many studies having been done using nanocomposites for cardiovascular implants, all the works need to be reviewed extensively for the development of a viable heart implant. The prime motive of this review work is to summarize various studies done on nanocomposite cardiovascular applications especially for bypass grafts and stents.…”

Polymeric nanobiocomposites for biomedical applications

“…These cells (i.e., EC, EPC, and stem) are capable of assisting the adhesion of the vascular graft on the target site and in the formation of fully functioning endothelium with self-healing capacity (as shown in Figure 5). 216 In addition, Tan et al 217 functionalized the POSS-PCU stents by immobilizing anti-CD34 antibodies resulting in nanocomposites that were able to improve hemocompatibility and initiate endothelialization. Similarly, Zhao et al 218 studied the effect of pore size on the POSS-PCU on hemocompatibility and endothelialization.…”