NEW YORK (Reuters Health) - The active ingredient in an herbal extract, used for hundreds of years in China, appears to halt cyst growth and progression of polycystic kidney disease in vitro and in a murine model. Triptolide is the first agent identified and developed in the laboratory with the potential to halt this currently untreatable disease.

Triptolide is derived from Tripterygium wilfordii Hook F, also known as the "Thunder God Vine." Triptolide induces apoptosis, arrests cell growth and down-regulates expression of genes that promote inflammation and cellular growth.

A tea made from the vine, Li Gong Teng, is used in traditional Chinese medicine as a treatment for inflammation, cancer and auto-immune diseases.

In research published in the March 5th early edition of the Proceeding of the National Academy of Sciences, Dr. Craig M. Crews of Yale University in New Haven, Connecticut, and colleagues have identified "an as-yet undescribed mechanism of the action of triptolide and an ability to stimulate calcium ion release, arrest cell growth and reduce cyst progression in a murine model" of polycystic kidney disease.

Dr. Crews' team showed that polycystin-2, a mutation of the gene associated with autosomal-dominant polycystic kidney disease, is a candidate target of triptolide. Triptolide causes calcium ion release, resulting in polycystic kidney disease epidermal cell growth arrest and attenuates in vivo cyst progression.

If triptolide proves to be well-tolerated, it may be a "promising therapeutic candidate" for polycystic kidney disease, Dr. Crews and colleagues conclude.