L.J. Gonez,
A.M. Holland, G. Naselli, L.C. Harrison
The cure of
type 1 diabetes will require either replacement or regeneration of insulin-producing
pancreatic islet beta cells, together with treatment to prevent their
immune-mediated destruction. The beta-cell mass in the adult pancreas
possesses the ability to undergo limited regeneration in response to
injury or increased physiological demand. Identifying the progenitor
cells involved and understanding the mechanisms leading to their maturation
will open new avenues for type 1 diabetes treatment. However, despite
steady advances in determining the molecular basis of early pancreatic
development, the identification of adult pancreatic stem cells or beta-cell
progenitors and the molecular mechanisms underlying beta-cell regeneration
remain unclear.
We have created
a double transgenic mouse model expressing the enhanced green fluorescent
protein (EGFP) under the control of the pancreatic beta-cell transcription
factor Pdx1 promoter and a temperature-sensitive version of the
immortalizing SV40 large T antigen under the control of the H2Kb promoter.
This model enables detection of beta-cell differentiation by EGFP expression
and conditional immortalization of cell populations of interest.
We isolated
ductal cells from adult pancreata of transgenic mice and showed that
these cells could be maintained in vitro. Moreover, a subpopulation
of adherent cells from ductal preparations differentiated into beta
cells expressing Pdx1, indicating that stem-progenitor cells exist in
adult pancreatic tissue (Fig 1). Furthermore, by analogy with adult
stem cells from other somatic tissues, we found that adult pancreatic
tissue contains cells with a ‘side population’ (SP) phenotype,
defined by the ability to exclude the Hoechst 33342 dye (Fig. 2A, B).
SP cells generate epithelial colonies when cultured on Matrigel (Fig
2C). The phenotype and differentiation potential in vitro and
in vivo of the colony-forming cells is being determined.
Download
Figures
Return
to Pancreas Development
