Diseño de biomateriales inyectables para aplicaciones biomédicas y farmacéuticas: Pasado, presente y futuro de los implantes generados in situ

The implantation of solid macroscopic biomedical materials requires conventional surgical procedures, which are commonly associated with extensive tissue damage. In an attempt to overcome these limitations, matrices that may be inserted through minimally invasive methodologies (injection) have been designed. Implants, after injection, may be classified, in accordance with their structural properties, into two categories: (1) implant materials that have no structural or continuous integrity or (2) those that are structurally continuous or integral. The employment of the first method is based on the injection of micro or nano particles, suspended in a biocompatible vehicle. However, the fact that these implants do not possess mechanical properties means that they may migrate from the site in which they have been inserted. In an attempt to overcome this drawback, system combining: (1) low viscosity and high fluidity on injection with (2) a subsequently pronounced increase in mechanical properties, leading to the formation of a solid implant with well defined limits. The present work provides a concise and detailed introduction to the different strategies that have been developed in the design of this type of implants over the past 20 years, as well as an assessment of the future perspectives within this sphere.