Immune rejection by the recipient is a major barrier to pancreatic islet transplants from donors becoming routinely available for the treatment of type 1 diabetes.

One way to overcome this is to place the islets — groups of insulin-producing cells — inside microcapsules made of a material that is less likely to provoke an immune response.

However, the process of microencapsulation can result in large numbers of empty capsules, which means a high volume of implant to achieve the required result. This increases the risk of immune reaction.

Now, researchers from the University of the Basque Country, in Spain, have developed a magnetic system for purifying the microcapsules that separates out the empty ones.

They describe the purification system, and how they tested its product in rats, in an International Journal of Pharmaceutics paper.

The study showed that, after implantation with "magnetically purified" islet microcapsules, rats induced to develop diabetes achieved and retained normal blood glucose levels for nearly 17 weeks.

"One of the drawbacks of islet transplants is the long-term use of immunosuppressant drugs to prevent the immune rejection of the transplanted islets; these drugs lower the patient's defenses and entail serious medical complications," explains first study author Albert Espona-Noguera, of the university's School of Pharmacy.

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