Inflammatory response, tissue compatibility

Historically, in vivo biocompatibility has been qualitatively assessed by histological evaluation of explanted devices.6 The presence or absence of specific inflammatory and fibrotic cell types and the degree and duration of the incidence of these cells at the implant site can be correlated to arelative degree of success or failure in terms of tissue compatibility. However, this common implant, sacrifice, explant, and evaluate single-time-point-per-animal approach is quite limited in assessment of time-depen-dent phenomena (e.g., direct assay of molecular and cellular mediators) associated with the progression of the inflammatory response and the development of the FBR. 

CaP ceramics are characterized by low degradation rates, fragility, weak fatigue resistance and easy rupture, but good tissue compatibility and response [339]. Their ability to bond directly to the bone together with the lack of toxicity and inflammatory reaction in-vivo have made CaP ceramics attractive in the biomedical field. However, their slow biodegradability has raised issues about their use in some of its applications. The introduction of porosity by specific factors and cells is reported to address the problem [340]. the release of conjugated implants proceeds in a controlled manner after an initial burst release. 

PVA hydrogels are non-bio degradable and relatively bio compatible and can be easily fabricated since they possess high stability under a range of temperature and pH conditions [43]. Their structural mechanical properties are similar to those of human soft tissues and provoke a limited inflammatory response [54]. 

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