In some cases, size still matters
The size of a medical implant affects its service life
Asya Gorina, Vesti
Various kinds of implants are able to fight a variety of ailments, ranging from infectious diseases to cancer. But despite the effectiveness of this technique, it is obvious that sooner or later the immune system will detect a foreign body inside the body and begin to reject it. And this threatens not only the effectiveness of treatment, but also the life of the patient.
A group of bioengineers from the Massachusetts Institute of Technology found that the creation of medical implants of a certain size can extend their service life before the device is rejected. In the future, this discovery may lead to the development of long-term treatments for diseases that require injections or surgery to eliminate.
The research by MIT scientists began back in 2008, when bioengineers first tried to create an artificial pancreas for the treatment of diabetes. The work was aimed at replacing islet cells, which immediately respond to an increase in blood sugar levels by releasing insulin. These cells cease to function in people suffering from type I diabetes mellitus.
During preclinical trials, scientists implanted a number of pancreatic islet cells enclosed in alginate implants directly into the abdominal cavity of mice with diabetes. Analyzing the results of the experiment, the researchers made an interesting observation.
They found that large implants of 1.5 millimeters in size, when inserted into the body of a mouse, are less likely to provoke the formation of scar tissue (which interferes with the functioning of a medical device) than small implants with a diameter of about 0.5 millimeters.
One and a half millimeter implants turned out to be the longest-lasting
(photo by Andrew Bader, Omid Veiseh, Arturo Vegas, Anderson/Langer Laboratory, Koch Institute/MIT).
Just four weeks after the devices were introduced into the mice, the small implants stopped working and were completely surrounded by scar tissue — this is the reaction of the immune system to a foreign body. Larger implants lasted five months longer, and in total provided the body with the necessary therapy for six months.
Moreover, large devices with a diameter of 1.5 millimeters independently reacted to changes in blood glucose levels and attracted much fewer of the rodents' own immune cells, according to a press release from Designing better medical implants.
During the experiment, scientists tested implants of two sizes made of various materials — stainless steel, glass, polystyrene and polycaprolactone. It turned out that the size of the device plays an important role regardless of what it is made of: larger implants have always served longer.
Now bioengineers will have to conduct experiments with implants of other sizes in order to identify a pattern and choose a universal ideal size. An article with the results of the study was published in the journal Nature Materials (Veiseh et al., Size- and shape-dependent foreign body immune response to materials implanted in rodents and non-human primates).
Portal "Eternal youth" http://vechnayamolodost.ru22.05.2015