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See Blood Vessels Grow to the Islet Sheet
August 5th, 2012
The Islet Sheet is the perfect environment for islets of Langerhans to thrive and deliver insulin as needed to the body of a person with diabetes. Once the sheet is implanted, nutrients (sugar, amino acids, lipids) are provided by the vascular tissues surrounding the implant. Then the islets react to glucose and release insulin exactly as needed.
Oxygen is the limiting nutrient on cells, and we must ensure that the islets in the sheet get enough all the time. Blood vessels near the islets — in the tissues surrounding the Islet Sheet — deliver the needed oxygen, and the islets’ demand for oxygen causes those blood vessels to grow.
Jonathan Lakey’s research group has developed a beautiful and interesting new way to image and measure this vascular adaptation. Rahul Krishnan led this work. At the recent Transplantation Society meeting in Berlin, Mr. Krishnan presented this study in an oral session.
Presented at Transplantation Society meeting, Berlin, July 2012
Click here for a high-quality PDF of the data.
The images were created by putting a clear window in the back of mice, providing a view of implanted islets and their surrounding tissue in two forms. The top set of images in the PDF shows the first group of islets: syngeneic mouse islets contained in an Islet Sheet, after implant and (below) 7 days later. In the second test, porcine islets were contained in an Islet Sheet (bottom set of images, after implant and 7 days later below). Vascular growth to feed the islets is shown by four different imaging methods. The method shown in the detail below — hemoglobin oxygen saturation — essentially shows availability of oxygen:
I think you will agree that the increase in oxygen supplied to the Islet Sheet is remarkable.
This paper shows that, at seven days post-implant, vascular service to islets in the Islet Sheets is similar to what occurs with unencapsulated islets. This supports our belief that the Islet Sheet will normalize blood sugars in people with diabetes.
Scott,
Check out Beta-02.com. They are a company out of isreal who claim to have an answer for the oxygen problem. They like many other research groups have claims but no current results in human studies. Either way I’m glad you are finally seeing the sheet come to life!
Dear Scott,
You said 2012 is the crucial year for the Islet Sheet, because tests on big animals will take place and will substantiate its success.
What is the status of your trials on big animals?
Dear Samer,
It’s happening. We are collaborating with Jonathan Lakey’s group at UCI. As I write this we are regulating a diabetic pig, learning about the best insulin dosing. For the first time in such an experiment we are using CGM (Thanks, Dexcom!) to help regulate the diabetes. When the pig is well controlled with insulin we will be implanting Islet Sheets with pig islets. We are happy to finally be doing the studies we have been talking about for three years. Let’s all hope for success.
Scott King
All the best, Scott.
Looking forward to hearing the good news.