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Monitoring Stem Cell Research 
Interconversion between pancreas and liver has also been 
demonstrated starting v\hth pancreatic stem cells, in which mouse 
pancreatic cells repopulated the liver and corrected metabolic liver 
disease. For pancreas, however, the possibility of solutions to the 
scourge of diabetes has been a driving force in efforts to define a 
stem cell that could regulate insulin in a normative, glucose- 
dependent fashion. The success of the Edmonton protocol,^^® where 
cadaveric pancreatic islets are transplanted into patients, has 
provided a glimmer of hope, but more readily-available sources of 
insulin-secreting cells are needed. Fortunately, there seems to be no 
shortage of potential candidates that can form insulin-secreting cells. 
The pancreas itself appears to contain stem/progenitor cells that can 
regenerate islets in vitro and in vivo. Studies indicate that these 
pancreatic stem cells can functionally reverse insulin-dependent 
diabetes in mice.^^^ Similar pancreatic stem cells have been isolated 
from humans and shown to form insulin-secreting cells in vitro , the 
hormone glucagon-like peptide- 1 appears to be an important 
inducing factor of pancreatic stem cell differentiation. Interestingly, 
the same hormone could induce mouse intestinal epithelial cells to 
convert into insuhn-producing cells in vitro, and the cells could 
reverse insulin-dependent diabetes when implanted into diabetic 
mice.^^® Besides pancreatic and intestinal stem cells, other adult 
stem cell types showing the ability to secrete insulin and regenerate 
damaged pancreas include bone marrow®'^’®® and liver. Genetic 
engineering of rat liver cells to contain the pancreatic gene PDX-1 
has also been used to generate insulin-secreting cells in vitro-, the 
cells could also restore normal blood glucose levels when injected 
into mice with experimentally-induced diabetes. 
CORNEAL LIMBAL STEM CELLS 
Corneal limbal stem cells have become commonly used for 
replacement of corneas, especially in cases where cadaveric donor 
corneas are insufficient. Limbal cells can be maintained and cell 
number expanded in culture, grown on amniotic membranes to 
form new corneas, and transplanted to patients with good success. 
A recent report indicates that human comeal stem cells can also 
display properties of functional neuronal cells in culture. Another 
report foimd that limbal epithelial cells or retinal cells transplanted 
into retina of rats could incorporate and integrate into damaged 
retina, but did not incorporate into normal retina.'^ 
MAMMARY STEM CELLS 
PRE-PUBLICATION VERSION 
