For the more than 1 million Americans who live with Type 1 diabetes, daily insulin injections are literally a matter of life and death. And while there is no cure, a new device may help manage the disease.
In Type 1 diabetes, insulin-producing pancreatic cell clusters (islets) are destroyed by the body’s immune system. The new method implants hundreds of thousands of islet cells into a patient. They are protected by a thin hydrogel coating, and more importantly, the coated cells are attached to a polymer thread and can be removed or replaced easily when they have outlived their usefulness.
Transplantation of stem-cell-derived, insulin-producing islet cells is an alternative to insulin therapy, but requires long-term immunosuppressive drug administration. One approach to avoid the immune system’s response is to coat and protect the cells in tiny hydrogel capsules, hundreds of microns in diameter. However, these capsules cannot be taken out of the body easily, since they’re not connected to each other, and there are hundreds of thousands of them. The ability to remove the transplant is key because of the potential of tumors forming when stem-cell-derived, insulin-producing cells — the most promising cell source for Type 1 diabetes cell therapies — are used.
Taking inspiration from the way water beads on a spider’s web, researchers first attempted to connect the islet-cell-containing capsules through a string, but determined it would be better to put the hydrogel layer uniformly around an ionized, calcium-releasing, nanoporous polymer thread. The device starts with two sterile nylon sutures twisted in a helix, then folded over to facilitate the subsequent nanoporous structure coatings. Placed onto that thread is a thin layer of islet-cell-containing alginate hydrogel, which adheres to the helical, nanoporous thread, similar to dew drops sticking to the spider silk. Alginate is a seaweed extract commonly used in encapsulated cell transplantation.
This thread — called TRAFFIC (Thread-Reinforced Alginate Fiber For Islets enCapsulation) — was inspired by a spider’s web, but is even better because the hydrogel covers the thread uniformly, eliminating gaps between the capsules that could cause scar tissue. Since the thread is twisted and porous, the hydrogel won’t slip off as it would on a single, smooth piece of material.
This therapy would involve minimally invasive laparoscopic surgery to implant approximately six feet of hydrogel-coated thread into the patient’s peritoneal cavity.