Precise timing enabled pig-to-rat transplants to cur...( May 16 2005 -- Scientists at Washingto...)

Precise timing enabled pig-to-rat transplants to cure diabetes

May 16, 2005 -- Scientists at Washington University School of Medicine in St. Louis have learned that a temporal "window of opportunity" was critical to their earlier successes in treating diabetic rats with embryonic pig tissues.

In those experiments, published in 2004, researchers were surprised to find that they didn't have to give anti-rejection drugs to diabetic rats treated with embryonic pig cell transplants. They had expected rats that received no immune suppression would reject the transplants. Instead, the new tissues engrafted with little difficulty, curing the rats of their diabetes.

In a new study to be published in the September issue of Transplant Immunology and currently available online, senior investigator Marc R. Hammerman, M.D., the Chromalloy Professor of Renal Diseases in Medicine, presents evidence that he and colleague Sharon A. Rogers, research instructor in medicine, harvested the embryonic pig tissues at precisely the right point in their development.

"When we again harvested the transplant tissues 28 days after fertilization, it reproduced our earlier results, but if we moved the time of harvesting back to 35 days after fertilization, the rats rejected the pig tissues and continued to be diabetic," says Hammerman, who is an endocrinologist and director of the Renal Division at Barnes-Jewish Hospital.

Hammerman and Rogers are leaders in the emerging field of organogenesis, which focuses on growing organs from stem cells and other embryonic cell clusters known as organ primordia. Unlike embryonic stem cells, which can become virtually any cell type, primordia are locked into becoming a particular cell type or one of a particular set of cell types that make up an organ.

In their earlier studies, Hammerman and Rogers had shown that transplantation of pig pancreatic primordia into diabetic rats cures their diabetes permanently without the need for immune suppression. The pig primordia are transplanted into th
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Contact: Michael C. Purdy
purdym@wustl.edu
314-286-0122
Washington University School of Medicine
16-May-2005

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