Inflammatory Responses to Biomaterials

Abstract

Implanted biomedical devices are of increasing importance in modern medical care. However, surprisingly little is known of the factors that determine biocompatibility of the materials used in these devices. These materials, although generally inert and non-toxic, can mediate a variety of adverse reactions, including inflammation, fibrosis, coagulation, and infection. This brief review focuses on the inflammatory responses (including fibrosis) that commonly occur around implanted biomaterials. Host proteins that spontaneously associate with implant surfaces are important determinants of the acute inflammatory response. In this regard, adsorbed fibrinogen appears particularly pro-inflammatory. Chronic inflammatory processes, in many cases in response to fragments of implanted biomaterials, may cause implant failure. In the case of silicone-filled mammary prostheses, the extravasation of silicone gel has been held responsible for a number of complications, including silicone granuloma, synovitis, connective-tissue disease, and lymphadenopathy. In some instances, material-mediated inflammatory responses may even cause degradation of the material itself (via oxidative products released by implant-associated inflammatory cells). Overall, there is insufficient knowledge of the determinants and mechanisms of host: implant responses. A clear understanding of tissue:biomaterial interactions will be required both to explain the pathogenesis of many implant-mediated complications and to aid in the development of more biocompatible materials for implantable devices.

Species and Density of Implant Surface Chemistry Affect the Extent of Foreign Body Reactions

“…11,13,19,20,[56][57][58] The collagenous capsule acts as a barrier to the diffusion of drugs and also blocks the supply of nutrients to the encapsulated cells in cell delivery systems. 11,[18][19][20]59 By diminishing biomaterial-mediated fibrotic reactions and accompanied collagenous diffusion barrier formation, the drug release properties, life-span and sensor sensitivity could be significantly enhanced.…”

“…9 However, many of these medical devices fail to produce long term therapeutic effect raising serious concerns over the efficiency of these implants. [10][11][12][13][14][15][16][17] For example, the chemotherapeutic doxorubicin delivering millirods has been reported to lose efficacy 8 days post subcutaneous implantation. 8 .…”

A randomized open‐label study of immediate versus delayed polylactic acid injections for the cosmetic management of facial lipoatrophy in persons with HIV infection

“…Indeed, no systemic effects on any of the studied blood parameters, including CD4 cell count and viral load, were observed in this study. PLA has advantages over other facial implants in that it is hypoallergenic and biodegradeable, unlike silicon particles, which remain permanently resident in the skin and may trigger inflammatory reactions [10]. Additionally, the administration technique enables individualization to suit the patient's facial contours and leads to development of increased skin thickness but with retention of normal skin appearance and texture.…”

Intracellular protein phosphorylation in adherent U937 monocytes mediated by various culture conditions and fibronectin-derived surface ligands

“…In addition to the role of protein conformation in modulating receptor recognition and cellular function, inconsistencies in the literature exist between the type and amount of adsorbed proteins and the subsequent cellular behavior [4,5]. For example, monocyte adhesion on a poorly adhesive surface is enhanced by adsorbed IgG [6], while others have shown that fibrinogen is more critical for phagocyte adhesion on biomaterials [7]. Others and we have demonstrated that macrophage adhesion is mainly modulated by the substrate and the extracellular matrix protein such as fibronectin [8,9].…”