The success rate for islets surviving for more than 1 year with an insulin-free patient was pretty dismal until this last year when the Alberta (Canada) experience was reported. The efforts of this group improved considerably on earlier results.
However, problems remain, especially with the availability of donor islets for transplantation. The number of islets injected for this procedure usually required 2 donors per patient. Also, of the patients reported in the Alberta study, at least half of them required a second transplant and some a third. Thus, 4 donors are often required for these patients, far more than for the whole organ transplant. There are currently only about 5000 human pancreases that become available in the United States for transplantation each year. Only 2500 are thought to be viable for islet isolation, thus only about 5-700 people will benefit. So, this girl may be in for 2-3more transplants. and with the above information, large scale implementation for all those type I juvenile diabetes is dismal.
However, stem cell research may solve this problem in two ways:
Intersting these islet cells are not "terminal cells" but undergo replacement at the rate of about 2%/month.
The new islets can derive from existing islets, a process known as replication, or from protodifferentiated stem cells, referred to as islet neogenesis.
The objective is to identify islet stem cells and expand islet numbers through in vitro (in test tubes or culture plates ) cultivation before transplantation.
Several investigators, both in the United States and in Europe, are working with fetal islet cell clusters as the ideal starting material for islet expansion. These are the supposed stem cells in the normal fetal development of islets. The thinking is that if these clusters can be kept in an environment that promotes development and differentiation, perhaps they can be induced to produce islets indefinitely in a culture!
A second approach is to identify the stem cell population in the adult pancreas and culture them in appropriate conditions to induce expansion in number and development into viable islets.
This would represent a step forward in making sufficient islet numbers available to treat a significant portion of the diabetes patient population.
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