After American and Brazilian researchers implanted 23 newly diagnosed type 1 patients with their own adult stem cells, 12 of the patients became insulin-free for periods lasting from 14 to 52 months (the mean was 31 months).

The researchers, from the University of São Paulo and Northwestern University near Chicago, used a method called autologous nonmyeloablative HSTC (hematopoietic stem cell transplantation), in which they transplanted immature blood stem cells into the patients after killing their immune cells with powerful toxins.

Because the stem cells had not been "programmed" to destroy insulin-producing beta cells, they allowed the patients' remaining beta cells to regain their function. The scientists noted increases in the patients' C-peptide levels, a common indicator of properly functioning insulin production.

The researchers had originally implanted adult stem cells in 15 patients, aged 13 to 31. Most of them became insulin-independent for a mean period of almost 19 months. But outside researchers questioned whether the results were caused by a prolonged "honeymoon" period brought on when the patients extensively altered their eating and exercise habits. (It's not uncommon for people who have been newly diagnosed with type 1 to enjoy an insulin-free period after they make dramatic changes in behaviors that aggravate the condition. In almost all cases, though, the "honeymoon" ends, and the patients must begin taking insulin again.)

In response, the American and Brazilian team added eight more type 1 patients to the study, paying special attention to their C-peptide levels after the implants. They found that in the 12 patients who experienced prolonged insulin-free intervals, C-peptide levels increased 349 percent from their pre-transplantation levels over a 24-month period. At 36 months, their C-peptide levels were still almost 324 percent of their pre-transplantation levels. A1c levels in the group's members remained below 7% throughout their insulin-free periods.

Although the results of the transplantation experiment are promising, the procedure itself is radical. Patients must have their immune systems suppressed by powerful drugs before receiving the stem cells. Significant percentages of the study's 23 patients experienced troubling side effects:

• Two patients (8.7 percent of the group) developed pneumonia while undergoing immunosuppression therapy.
• Nine patients (39 percent) developed low sperm counts after exposure to one immunosuppressant drug.

The results of the study have been published in the April 15 issue of the Journal of the American Medical Association.