Four of the 23 patients who took part in the study remained insulin free for at least three years and one patient went without insulin injections for more than four years.
But the treatment, which included the use of highly toxic immune-system suppressing drugs, was not without troubling side effects.
Two patients developed pneumonia while hospitalized for immunosuppression therapy, and nine developed low sperm counts as a result of exposure to one toxic drug. The latest results from the study appear in the April 15 issue of the Journal of the American Medical Association.
Diabetes specialist David M. Nathan, MD, who was not involved with the study, tells WebMD that the stem cell treatment is promising, but he adds that the side effects remain troubling.
“This is a pretty bold intervention that can involve serious complications,” he says. “The hope is that this will lead to more benign treatments that can keep people off insulin.”
Stem Cells for Diabetes
All the patients included in the stem cell study had been diagnosed with type 1 diabetes within six weeks of treatment, and all were producing some insulin on their own, although this production was greatly diminished.
The goal of the treatment was to kill the immune cells that were killing the insulin-producing cells and replace them with immature cells not programmed to disrupt insulin production.
The treatment, called autologous nonmyeloablative hematopoietic stem cell transplantation (HSCT), involved several steps.
Soon after diagnosis, the patients were given drugs to stimulate production of blood stem cells. The blood stem cells were then removed from the body and frozen.
Patients were hospitalized and given the toxic drugs that killed their circulating immune cells, and then the harvested blood stem cells were put back into the patient.
The first patient to receive the treatment did not improve, probably because he had too few functioning insulin-producing cells left.
But 20 of the next 22 patients treated with the experimental therapy were able to do without insulin injections or greatly reduce their insulin use for a few months to several years.
Patients who remained insulin-independent showed significant improvement in their ability to produce insulin two years after treatment, compared to pre-treatment production levels.
The ability to show direct improvement in insulin-producing cell function is important because critics have questioned whether the treatment really works.
Soon after being diagnosed with type 1 diabetes, many patients enter what is known as a “honeymoon” period, thought to result from improved diet and lifestyle.
It has been suggested that the early improvements seen in the patients who got the stem cell treatment was because of this lifestyle-related remission and not the treatment.
“This treatment actually stopped the autoimmune process and the remaining [insulin-producing] cells that were not destroyed worked well enough to keep many of these patients off insulin,” Nathan says.
FDA Considering Larger Trial
Study co-author Richard Burt, MD, of the Northwestern University Feinberg School of Medicine, concedes that the side effects seen with the treatment were not negligible, but he adds that the approach is far less toxic than immune system-suppressing therapies given to cancer patients.
“I think people will have to judge for themselves if the potential risks of this treatment outweigh the long-term risks associated with type 1 diabetes progression,” he tells WebMD.
The treatment has not been tried in young children. The youngest study participant was 13 and the oldest was 31.
And patients who have had diabetes for some time and no longer produce any beta cells probably would not benefit.
Burt says the next step is to conduct a larger, randomized trial to confirm the usefulness of the treatment in newly diagnosed patients who are still producing some insulin on their own.
The FDA is currently considering whether to allow such a study. The 23 patients who took part in the pilot study were all treated in Brazil.
“This is the first time in the treatment of diabetes that after one intervention patients no longer required any therapy,” Burt says. “And now we have many years of follow-up.”