“When I considered the matter thirty years ago, the Islet Sheet looked to be the most promising new therapeutic technology. Thirty years later, clinical and scientific knowledge have expanded greatly—but nothing has happened to change my mind. I believe that implantation of Islet Sheets is as close as we will get to a cure in my lifetime.”
—Scott King, founder and president of Islet Sheet Medical
Researchers on type 1 diabetes have long sought ways to replace nonfunctioning islets. Islet transplantation (the so-called Edmonton Protocol) is the best therapy to date, but it can be maintained only with immune-suppression drugs that cause serious side effects. In supporting the Islet Sheet Project, we seek to develop a better diabetes therapy using thin-sheet encapsulation—an implanted bioartificial pancreas.
In this technology, the islets are protected by a barrier, so they can release insulin and normalize blood glucose levels without the ongoing need for immunosuppressant drugs or insulin injections. Further, the thin sheet will make possible the use of a greater range of islets, including those from animals and stem cells.
About the Islet Sheet
The patented Islet Sheet was developed by Islet Sheet Medical, a San Francisco biotechnology company, in collaboration with a team of leading diabetes researchers. It is one version of a bioartificial pancreas, an implanted device that responds to changing blood sugar levels with the release of insulin in real time, mimicking the normal function of pancreatic islets.
Configured as a sheet just .3 millimeters thick, the Islet Sheet has three components: islets (currently obtained from donors), a reinforcing mesh for strength and durability, and highly purified alginate, which completely encapsulates the other components. A central core contains islets suspended in alginate. The core and mesh are surrounded by and bonded to layers of acellular, immuno-protective alginate.
Islets are kept alive by diffusion of oxygen, glucose, and other nutrients into the sheet. The sheet is so thin that passive diffusion alone allows nutrients to reach all the way through the sheet to support islet life and function. To maximize diffusion the reinforcing mesh is greater than 80 percent open. The sheet surface is mirror-smooth on the cellular scale, made via a proprietary process using highly purified and biostable alginate.
The Islet Sheet can be made in whatever size and shape is best for the implant. A standard sheet the size of a business card (about 4 x 6 cm) can sustain approximately 100,000 islets, so six sheets should be enough to achieve euglycemia (normal blood sugar). Sheets are sutured in place during simple laparoscopic surgery. (The perimeter is further reinforced for suturing.)
Advantages of the Islet Sheet
Islet Medical’s thin-sheet device incorporates several design improvements over competing approaches. These include:
- The sheet is fully retrievable and replaceable, ensuring safety
- Uniform thinness permits sufficient oxygen diffusion to all cells
- Complete immuno-isolation prevents destruction of islets by immune processes
- The first macroencapsulation device that does not provoke a significant fibrotic response
- Thin-sheet technology is compatible with many different cell lines and islet sources.
The Islet Sheet has been in development for several decades. Thus far, Islet Medical’s chief collaborator has been Professor Jonathan Lakey of the University of California–Irvine, who made the islets used to develop the Edmonton Protocol. Experiments have proven the viability of this form of islet encapsulation.
Currently the project is in preclinical studies with animals, and the pace of development will soon accelerate. Hanuman Medical Foundation is excited to announce a major expansion of the research effort, projected to reach the goal of clinical trials by 2013, perhaps even earlier.
- The Islet Sheet Project has created a bioartificial pancreas using thin-sheet encapsulation technology, which protects and sustains the islets.
- Islet Sheet Medical, working with leading researchers, developed the patented Islet Sheet design over several decades.
- The Islet Sheet offers many advantages, which experiments have borne out. A new project expansion should bring it to clinical trials in 2013.