The pancreas and liver arises from adjacent areas in the anterior endoderm of the developing embryo. This close relatedness underlies the possibility of direct reprogramming of the liver cells or hepatocytes towards pancreatic beta cells.
In the present study we show that hepatoblasts in undissociated early-stage liver buds can be reprogrammed towards a beta cell-like cell fate by ectopic expression of the pancreatic transcription genes (Pdx1, Ngn3, and MafA) using a polycistronic adenovirus. The reprogramming happens by 3 days after Ad-PNM transduction. Dissociated hepatoblasts isolated from different developmental stages of embryonic livers, which are considered as hepatic progenitor cells, also could be reprogrammed efficiently by Ad-PNM. This was associated with approximately 20% (E18) to 70% (E11) of hepatoblasts expressing insulin and C-Peptide along with a significant increase in endocrine gene profiles and down-regulation of liver markers. Moreover the reprogrammed cells were seen to express GFP when hepatoblasts were isolated from Pdx1-GFP transgenic mice, indicating transcription of the endogenous Pdx1, a hallmark for genuine reprogramming. This allowed us to sort the green fluorescent cells which, upon stimulating with low (2.8mM) or high (20mM) glucose, failed to show significant glucose-sensitive insulin release. However, these cells could maintain the blood glucose levels of diabetic mice at a stable and normal level for one month after transplantation.
In summary, hepatic progenitor cells, which may possess a similar epigenetic pattern to pancreatic progenitor cells, can be reprogrammed by overexpressing pancreatic transcription factors. This may be a promising resource of cell therapy for diabetes.
University of Minnesota M.S. thesis. December 2012. Major: Stem cell biology. Advisor: Dr. Jonathan M.W.Slack. 1 computer file (PDF); vi, 54 pages.
Reprogramming of hepatic progenitor cells towards a beta-cell character using Pdx1, Ngn3 and MafA.
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