Pig Islets Still Producing Insulin After Ten Years In Diabetic Man
Ten years ago, Michael Helyer, a New Zealand man with type 1 diabetes for eighteen years, received a transplant of pig islets. Much to the surprise of researchers, the pig cells are still putting out insulin at this late date. In fact, it was Mr. Helyer who alerted scientists at Living Cell Technologies (LCT) that the cells were still functioning.
Mr. Helyer received the alginate-encapsulated neonatal pig islet cell injection into his abdomen in 1996, at age 41. By twelve weeks after the transplant, the islets were going strong, reducing Mr. Helyers need for insulin by thirty percent. Porcine (pig) C-peptide was detectable in his urine for eleven months. Although his insulin had returned to pre-transplant levels by week 49, improvement in control continued: his A1c at fourteen months was 7.8%, as compared to a previous 9.3%. After that, however, formal testing ceased until Mr. Helyer brought himself to the attention of scientists at LCT nearly ten years later.
When Mr. Helyer was given a laparoscopy at that time, abundant nodules were still seen throughout his peritoneum (the membrane lining his abdominal cavity). Biopsies of the nodules showed capsules containing live cell clusters, and the retrieved capsules produced a little insulin when placed in high glucose concentrations in a test tube. When Mr. Helyer was given an oral glucose tolerance test, it produced a small rise in insulin that tested out as pig insulin.
Scientists at LCT are just now set to begin a trial in Russia of such transplants. (See the article Pig Islets Soon Tested in Humans in our April/May issue for more information on that enterprise.) According to LCT, more advanced versions of Mr. Helyer's pig cell therapy, using neonatal pig islets encapsulated in an alginate gel, could be available within two years if the planned human trials are successful.