MIT scientists discover size of implant can affect immune system rejection
A team of researchersfrom MIT has discovered that creating body implants at a certainsize maximizes the amount of time they can spend operational in thebody before being neutralized by the immune system. In the future,the research could lead to longer term treatment avenues for diseasesthat could do away with the need for painful and repeated injections.
Without doubt, thehuman immune system is a wondrous thing. Over the course of ourspecies' short existence, it has protected us and evolved with us,but it also has the capacity to interfere and stymie avenues oftreatment offered by advances in medical science. Such is the casewith body implants, which are increasingly used as a long-term drugdelivery method.
The study that led tothe discovery started seven years ago as an attempt to create anartificial pancreas, in order to treat diabetes. The study aimed toreplace an individual's islet cells, which are responsible fordetecting high concentrations of blood sugar and trigger the releaseof insulin from the pancreas. These cells cease to function inindividuals suffering from Type 1 diabetes, preventing the body fromcoping with the sugar build-up.
During thetrial, the team implanted a series ofpancreatic islet cells encased in alginate implants directly into theabdominal cavity of diabetic mice, which would mimic the functions of a healthy pancreas, making insulininjections a thing of the past. However, the newly-implanted cellswould be incapable of performing their new function if they werecovered by scar tissue.
Theteam discovered that larger implants measuring 1.5 mm in diameterwere better suited to avoiding scar tissue build-up when compared tosmaller 0.5-mm variants. The smaller implants were found to beengulfed in scar tissue and ceased to function at around the four-week mark, however the 1.5-mm implant continued to function for animpressive six months after insertion. Furthermore, the largerimplants were able to respond to changes in glucose levels whileattracting less attention from the rat's immune cells.
Over the course of thestudy, the team trialled the two sizes of implants constructed out ofstainless steel, glass, polystyrene, and polycaprolactone. It wasdiscovered that the results invariably favored the larger analogue.The research represents a promising step forward in implantsurvivability, and could change the lives of millions suffering fromdiseases such as Type 1 diabetes
A paper on the team'sresearch is available on the online journal Nature Materials.