The term biocompatibility refers to the behavior of biomaterials in the living body. The most accepted definition of biocompatibility was given by D. F. Williams: “Biocompatibility refers to the ability of a biomaterial to perform its desired function with respect to a medical therapy, without eliciting any undesirable local or systemic effects in the recipient or beneficiary of that therapy, but generating the most appropriate beneficial cellular or tissue response in that specific situation, and optimizing the clinically relevant performance of that therapy” (Williams 2008, 2951). Attending to this definition, it is clear that all biomaterials, whether they will be used for drug delivery or tissue engineering, should present a biocompatible response.