Scientists at Penn State University have developed a thin protective coating that could make cell therapy for diabetes safer and longer-lasting by helping donor cells evade the body's immune system.
Cell therapy for diabetes aims to restore insulin production by transplanting specialized cell clusters known as pancreatic islets. However, the immune system recognizes these donor cells as foreign and attacks them. Patients therefore often need long-term immunosuppressive drugs, which can increase the risk of infections and other serious complications.
The new approach uses a jelly-like material called hydrogel to create what researchers describe as an “invisibility cloak” around the transplanted cells. The technology, known as biomimetic zona pellucida (BZP), was designed to mimic the thin protective layer naturally found around human egg cells.
The coating is designed to shield donor islets from immune attack while remaining permeable enough to allow the cells to release insulin into the bloodstream. This could potentially make it possible to use cell therapy without continuous immunosuppression.
The study, published in Nature Biomedical Engineering, tested the technique in diabetic mice. Researchers coated pancreatic islets with the BZP material and transplanted them into the animals.
The treated mice reached healthy blood sugar levels within about a week. Most remained free of diabetes for more than 100 days without continuously receiving immunosuppressive drugs. By comparison, uncoated cell therapies typically remain effective for a week or less when systemic immunosuppression is not used.
Developing the coating was not straightforward. The researchers spent eight years refining the technology to produce a hydrogel layer just 20 micrometers thick—far thinner than a human hair. The coating had to be thin enough to conform to the surface of living cells and cell clusters without interfering with their normal function.
The concept is based on the natural zona pellucida, a protein-rich layer surrounding egg cells. Researchers recreated its ultrathin structure and hardening process to protect transplanted therapeutic cells from the immune system.
The scientists say the technology could eventually have applications beyond diabetes. After further laboratory research, refinement and clinical trials, the BZP platform could potentially be adapted for immunotherapy and regenerative medicine, including approaches designed to protect therapeutic cells or stimulate tissue regeneration.
However, the current findings come from experiments in diabetic mice. Further studies will be needed to determine how long the protective effect lasts and whether the technology is safe and effective in humans.
The researchers see the coating as a potential platform for developing cell-based treatments that could avoid some of the major limitations of conventional transplantation, particularly the need for long-term immunosuppression.
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