Microscopic Coatings Protect Transplanted Islet Cells
Background:
For more than two decades, scientists here at the DRI have been developing ways to protect transplanted islets and promote their long-term survival. A potential solution sounded simple enough – encase the cells in a protective barrier (a process called cell encapsulation) that allows nutrients to flow in and insulin to flow out.
This encapsulation technology, however, has been met with many challenges. Scientists have constructed small, bubble-like casings called microcapsules to protect islets from inflammatory reactions and immune attacks, while permitting the nutrients to reach the cell. But the very construct of a microcapsule continues to prevent islets from thriving. Here’s why. While invisible to the naked eye, microcapsules are relatively large and the space within them is very big compared to the size of one islet cell – almost like a pea inside of a balloon. As a result, critical oxygen and other nutrients flowing in do not reach the many cells within islet efficiently.
Research Focus:
The Tissue Engineering group here at the DRI is developing a different cell encapsulation strategy using nanotechnology – following a similar process that’s been used in the microchip industry for years. By layering a microscopically-thin, “nanoscale” coating directly to the surface of the islet cell, nanoencapsulation accomplishes two things:
- Because this advanced cell encapsulation layer is so thin - almost as if it’s “shrink-wrapped” around the islet cells, oxygen and nutrients don’t have to travel far to reach the cells. And, the islet cells themselves can efficiently release insulin back into the bloodstream through that same, thin nanoencapsulation layer.
- Although thin and porous enough to let nutrients in, the nanoscale coating does offer protection to the transplanted islet cell by dampening the immune system’s response to attack the transplant.
In addition to passively protecting the cell, researchers believe these nanoscale layers can also be made more “active.” By attaching anti-inflammatory molecules to their surface, the nanoscale layers actively ward off attacks on the transplanted cell, and reduce adverse reactions to transplant stress, such as inflammation, clot formation and leukocyte (white blood cell) infiltration.
Because this nanoencapsulation strategy holds such promise, we’ve established a partnership with Dr. Jeffrey Hubbell, Professor and Director of the Integrative Biosciences Institute, and Professor of the Institute for Chemical Sciences and Engineering at Ecole Polytechnique Fédérale de Lausanne in Switzerland. Dr. Hubbell is world renowned for his work with biomaterials for tissue engineering and drug delivery. Our collaboration will focus on developing new encapsulation devices and investigating strategies for local drug delivery at the transplant site.
Leading to a Cure: How this Research Supports our Mission
By coating islet cells with nanoscale layers and creating a type of “camouflage,” transplanted cells will go unnoticed by the body. The coating prevents attacks from the immune system, could decrease the need for anti-rejection drugs, helps to avoid inflammation in the area of the transplant, yet still allows cells to sense glucose in the blood and secrete insulin.