Scientists have discovered the much sought-after pancreatic stem cells capable of generating beta cells essential for the production of insulin, in mice models.
The newfound progenitor cells will provide a potential target for therapeutic regeneration of beta cells in diabetes, provided that the results replicate in human studies also. "One of the most interesting characteristics of these (adult) progenitor cells is that they are almost indistinguishable from embryonic progenitors," said Harry Heimberg of the JDRF Center at Vrije Universiteit Brussel in Belgium and the Beta Cell Biology Consortium.
"In terms of their structure and gene expression, there are no major differences. They look and behave just like embryonic beta cell progenitors," the researcher added. Insulin is required for cells to take up blood sugar, the body's primary energy source. In people with certain types of diabetes, pancreatic beta cells lose the ability to produce sufficient amount of insulin, which in turn raises blood sugar levels. Previous studies did not show the existence of bona fide beta cell progenitors in the pancreas after birth.
According to the researchers, the elusiveness of this cell type reached a summit when genetic lineage tracing provided evidence that pre-existing beta cells, rather than stem/progenitor cells, are the major source of new beta cells in adult mice. "Most people gave up looking because they are so few and so hard to activate," Heimberg said.
In the latest study, the researchers tied off a duct that drains digestive enzymes from the pancreas. They showed that the injury led to a doubling of beta cells in the pancreas within two weeks. Heimberg said that the animals' pancreases also began producing more insulin, evidencing that the new beta cells were fully functional. He suspects the regenerative process is sparked by an inflammatory response in the enzyme-flooded pancreas.
The researchers also found that the production of new beta cells depends on a gene called Neurogenin 3 (Ngn3), which is known to play a role in the pancreas during embryonic development.
"The most important challenge now is to extrapolate our findings to patients with diabetes," Heimberg said.
The researchers agree that any potential diabetes treatment remains far into the future.
They, however, insist: "Our findings reveal the significance of investigating the feasibility of (1) isolating facultative beta cell progenitors and newly formed beta cells from human pancreas in order to expand and differentiate them in vitro and transplant them in diabetic patients and (2) composing a mix of factors able to activate beta cell progenitors to expand and differentiate in situ in patients with an absolute or relative deficiency in insulin."