Students Invent a Protective Pouch to Hold Transplanted Beta Cells

A team of five seniors and two freshmen at Johns Hopkins University has devised a little “pouch” to hold microcapsules of beta cells in the portal vein, from which the cells can send out insulin while safely protected inside. It’s made by sandwiching a porous cylinder of nylon mesh between two cylindrical metal stents, similar to the ones that are used to keep clogged blood vessels open.

The pouch is inserted into the abdomen from the femoral vein in the leg. First the compressed outer stent is threaded into the portal vein, where it pushes out on it harmlessly. Then the inner stent, surrounded by the nylon mesh cylinder, is compressed and inserted. Once in place, the inner stent snaps back to its original shape and the nylon mesh is held snugly against it.

Semi-permeable alginate microcapsules containing beta cells are injected into the space between the two metal stents, where they become trapped within the nylon mesh. The alginate microcapsules protect the cells from attack by the immune system. The openings in the mesh are big enough to allow blood through but too small to allow the microcapsules to escape.

The blood flowing though the cylinder nourishes the encapsulated cells trapped within the mesh and circulates the insulin they produce. The device allows for the microcapsules to be removed and refilled as necessary.

The Johns Hopkins staff has applied for a patent, and animal testing is expected to begin this summer. If those trials are successful, human trials would be next.

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Source: Johns Hopkins News Release

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