Intravascular Implant for Diabetes Cell Therapy

A group of undergrad students at Hopkins, working together with doctors and biomed engineers, developed a specialized implant for a potential treatment of type I diabetes. Designed for implantation inside the portal vein, this intravascular pouch has to be impregnated with insulin-producing pancreatic beta cells:

This pouch would keep microcapsules of therapeutic cells in one place, allowing them to thrive and send out needed insulin. The inventors say the same approach could be used in cell therapy for other ailments, including liver disease.
“I think it’s a brilliant idea,” said one of the project’s sponsors, Jeff W. M. Bulte, director of the Cellular Imaging Section in the Johns Hopkins Institute for Cell Engineering.
The pouch is formed by sandwiching a porous band of nylon mesh between two concentric metal stents, similar to the ones used to keep clogged blood vessels open. Once the stents are in place, microcapsules filled with helpful cells are injected into the gap between the stents, where they become trapped within the nylon mesh. Blood flowing through the vessel should nourish the encapsulated cells and circulate the proteins, such as insulin, produced by these cells.
The project is important because it could lead to better results from cellular therapy, in which live cells are injected to repair or replace damaged or depleted tissue. “It’s a device,” Bulte said, “that allows the microcapsules to be removed and reinserted if additional therapy is needed – a ‘yearly refill,’ for example – and the students have provided an ideal environment in which the encapsulated cells can thrive…”
The pouch components are made to be compressed and inserted with catheters that a physician can snake into the abdomen through the femoral vein in the leg. Using real-time imaging technology, an interventional radiologist can view and guide the minimally invasive procedure as it takes place. First, the doctor would insert the stainless steel outer stent, which would push out harmlessly on the elastic interior of the vein. Next, the doctor would insert the inner stent, surrounded by the porous nylon mesh. The inner stent is made of nitinol, a metal that snaps back into its original shape after being compressed for insertion. The inner stent matches the interior diameter of the vein. When all of the pieces are inserted, the nylon mesh is held snugly against the inner stent. A gap forms between the mesh and the outer stent, allowing blood to pass through.
At this point, the physician would use another catheter to inject the encapsulated cells between the stents, where the mesh would hold them in place. The tiny openings in the mesh, each about 250 microns in diameter, would allow blood to pass through to nourish the cells and disperse helpful proteins. But the openings are too small to allow the microcapsules to escape.

Press release: Students Invent Protective Pouch to Enhance Cell Therapy …
(hat tip: Medlaunches)