The effect of phosphorylcholine‐coated materials on the inflammatory response and fibrous capsule formation: In vitro and in vivo observations

Abstract

Abstract:Several experiments were performed to compare the in vitro adhesion of human macrophage and granulocyte inflammatory cells to polyethylene terephthalate substrate and the same coated with a phosphorylcholine (PC)-based polymer. The inclusion of various types of serum at different stages in the assay indicated that protein adsorption and passivation of the surface may be responsible for reducing the number of inflammatory cells adhering to the uncoated polyethylene terephthalate controls. In all of the assays performed there was a statistically significant reduction (p Ͻ 0.05; analysis of variance) of the number of inflammatory cells adhering to the PC-coated samples, linked to the ability of these surfaces to resist protein adhesion. Implantations of PC-coated stainless steel and high-density polyethylene USP control samples were made in a rabbit intramuscular model. Histological examination of the number of inflammatory cells present around the implant sites 4 weeks postimplantation showed there were 40% less cells associated with the PC-coated samples compared with control, but this was not statistically significant. Fibrous capsule thickness, however, whereas marginally less at 4 weeks, had almost completely regressed for the PC-coated sample at 13 weeks postimplantation and was statistically thinner (p Ͻ 0.01; Mann-Whitney U test) than the high-density polyethylene USP control. These findings support the view that low biointeractions observed for PC-based technology in vitro can result in reduced inflammation and foreign body reaction in vivo.

In vivo biocompatibility and stability of a substrate-supported polymerizable membrane-mimetic film

“…PC-based polymers have been widely utilized as biocompatible coatings for a number of implantable materials [18][19][20][21][22][23][24]. However, while such PC-based polymer coatings may offer high biocompatibility, they lack the unparalleled molecular control over surface order and chemistry offered by self-assembled supported lipid films, in particular the ability to generate bioactive materials through incorporation of membrane-based proteins and carbohydrates that may modulate the local biochemical milieu.…”

“…Moreover, these films have been fabricated on a limited number of substrates with relevance to implantable materials. PC-based polymers, however, have been used to modify a number of implantable biomaterials including Dacron s [18] and ePTFE vascular prostheses [19,20], polyethylene joint prostheses [21], medical grade stainless steel [22], and coronary stents [23,24], and have demonstrated excellent hemocompatibility and biocompatibility in vivo. However, the use of PC-based polymers does not create a uniform, closely packed array of PC groups at the host-material interface, and therefore, lacks the degree of structural control and versatility offered by self-assembled phosopholipid films.…”

Osteogenic Potential of BMP-2-Releasing Self-Assembled Membranes

“…A thin and continuous fibrous capsule also surrounded both membranes, which is consistent with other studies evaluating collagen or HyA biomaterials implanted at this location. [52][53][54][55][56] Using the fibrous capsule as a reference point for the membrane edges, the approximate thickness of membranes with and without BMP-2 after implantation was found to be similar. However, membranes without BMP-2 contained multiple voids within its structure, whereas membranes with BMP-2 showed a dense structure in which the membrane seemed to be completely filled with cells and the extracellular matrix (Fig.…”

The Fibrotic Response to Implanted Biomaterials: Implications for Tissue Engineering

“…PEG-based hydrogels have been shown to substantially reduce the immune response around biosensors implanted in rats (Quinn et al, 1997) while PHEMA coatings reduced clotting and protein adsorption to calcium monitors in dogs (McKinley et al, 1981). Phospholipid-containing materials designed to mimic the cell membrane have been shown to reduce adhesion of inflammatory cells and fibrous capsule formation around vascular devices (Goreish et al, 2004) while Abraham et al (2005) showed that formulations incorporating PEG and phosphorylcholine into PHEMA-based hydrogels greatly reduced protein adsorption. Alternatively, strategies may be directed towards augmentation of the foreign body response for tissue engineering.…”