To test this hypothesis, we designed a series of experiments generating LDPCs from two different species. First, we obtained an extremely pure population of hepatocytes from rat liver. Then, by fluorescently labeling and documenting the evolution of LDPC cultures set up with these hepatocytes, we were able to show that the LDPCs were also fluorescently labeled, strongly suggesting that they were directly derived from hepatocytes. The quantitative flow cytometric analysis of the initial and resultant cell populations indicated that hepatocytes were the only logical source for LDPCs. Next, we wanted

to show the origin of LDPCs in a transgenic mouse model, which would allow us to track the fate of hepatocytes. To accomplish this, we generated a double-transgenic AlbCreXRosa26 mouse strain, www.selleckchem.com/products/LBH-589.html which was previously generated and published by others.32 Again, using several different techniques, we showed that these animals activated and expressed β-galactosidase only in hepatocytes. Using purified hepatocytes from these animals, we found that the LDPCs

were also β-galactosidase positive, supporting the conclusion that they were derived directly from hepatocytes. These studies also showed two potentially unique mechanisms by which hepatocytes dedifferentiate into hepatic progenitors. One is by cell condensation or shrinkage, which is morphologically similar to cells undergoing apoptosis; the other is budding off from multinucleated learn more cell clusters reminiscent of cell division in yeast.33, 34 It will be important to confirm these observations by future studies. Another interesting finding was the up-regulation of mesenchymal markers CD44 and vimentin during this dedifferentiation process, suggesting an epithelial-mesenchymal transition.

This is particularly intriguing, given the known role of EMT in liver development and regeneration.35-37 However, the confirmation of EMT in the generation of LDPCs requires further studies. The other somewhat unexpected finding was the click here transient expression of some oval cell markers as hepatocytes dedifferentiated into LDPC. Based on the coexpression of OV-6 and LDPC markers by the majority of cells in culture, we believe that there is a single population of hepatic progenitors that are generated through a transient oval cell-like stage from hepatocytes. Having shown the ability of mature hepatocytes to dedifferentiate into LDPCs in vitro, we tested the potential biological relevance by demonstrating their ability to regenerate hepatocytes in an animal model. Therefore, we proceeded with a well-established transplant protocol consisting of retrorsine pretreatment and partial hepatectomy in rats. The presence of both PKH-labeled and Y-chromosome-positive hepatocytes in the recipient animals convincingly showed that transplanted LDPCs were able to engraft and redifferentiate into hepatocytes in vivo.