Shrink-Wrapping Cells with Protective Coatings
When insulin-producing islet cells are transplanted into patients with diabetes, the immune system seeks to destroy the donor cells. But what if we could “hide” the transplanted islet cells from the immune system? Then we could prevent the risk of rejection from an immune attack.
For years, researchers have been trying to do just that -- to camouflage islets by encasing them in protective barriers. But these cell encapsulation strategies largely have failed, in part due to the size of the capsules and the materials used to encase the cells.
Now, new technology is providing the DRI with tools to improve cell encapsulation methods. Rather than the large, one‐size‐fits‐all “bubble‐like” capsules used elsewhere, DRI investigators have developed a system that creates a tight-fitting shield around each islet – as if they are individually “shrink‐wrapping” each cell.
This “conformal” capsule
minimizes the space between the outer
barrier of the capsule and the islet
within, making it easier for oxygen and other nutrients to reach the cell. This allows the cell to sense blood sugar and release insulin without the delay typical of previous capsules.
And, because there is little wasted space inside each capsule, the thousands of transplanted islets will take up less total space, offering researchers more options for implanting them within a BioHub. The DRI also is developing and testing a new technique to double-coat the islets to further protect and stabilize the encapsulated cells.
Taking this promising encapsulation strategy a step further, researchers are developing ways to make the conformal coatings more “active.” They’re attaching special molecules to the surface that can help to decrease or eliminate inflammation and ward off an attack on the transplanted cells. The team is also incorporating oxygen promoters and other compounds within the coating materials to provide nutrients and additional protection.
Traditional microcapsules (left) leave empty space between the capsule barrier and the islet within, causing inefficient oxygen delivery to cells. The DRI is developing new protective coatings that fit tightly around an individual cell, like "shrink wrapping," which are more beneficial and can be used within a BioHub.