(94e) Biological Response Precision-Controlled By Spherical Pores

Implanted biomaterials, after approximately one month, are observed in an avascular, collagenous capsule – this outcome is referred to as the foreign body reaction (FBR). This reaction starts with recruited macrophages that then fuse into giant cells leading to the avascular, fibrotic healing. Such healing can be undesirable for implanted sensors, electrodes, drug delivery systems and other devices. We have developed a number of strategies based on polymeric materials to address this FBR. One such strategy will form the focus of this talk. We have fabricated hydrogel materials with uniform, interconnected 30-40 micron pores by a sphere-template method -- upon implantation the pores are infused by macrophages. The macrophages within the pores orchestrate a different healing process from that seen with non-porous materials or materials with non-optimal pore sizes. Macrophages are biomechanically directed to a unique phenotype that encourages reconstructive healing (M2). Thus, the inflammatory process is exploited to generate improved healing – a new biocompatibility. Reconstructive healing has been noted subcutaneously, percutaneously and within heart muscle, cornea and bone. The surprising and desirable outcomes from these implanted porous structures led us to commercialize them. The path from laboratory curiosity to a product and medical device that is now used in humans will be discussed.