Original Articles
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World J Gastroenterol. Mar 7, 2009; 15(9): 1057-1064
Published online Mar 7, 2009. doi: 10.3748/wjg.15.1057
Omentum facilitates liver regeneration
Ashok K Singh, Nishit Pancholi, Jilpa Patel, Natalia O Litbarg, Krishnamurthy P Gudehithlu, Perianna Sethupathi, Mark Kraus, George Dunea, Jose AL Arruda
Ashok K Singh, Krishnamurthy P Gudehithlu, Mark Kraus, George Dunea, Jose AL Arruda, Department of Medicine, Stroger Hospital of Cook County, Chicago IL 60612, United States
Ashok K Singh, Nishit Pancholi, Jilpa Patel, Krishnamurthy P Gudehithlu, Perianna Sethupathi, Mark Kraus, George Dunea, Hektoen Institute of Medicine, Chicago IL 60612, United States
George Dunea, Jose AL Arruda, University of Illinois at Chicago and the Chicago VAMC, Chicago IL 60612, United States
Natalia O Litbarg, Perianna Sethupathi, Loyola-Hines Medical Center, Maywood IL 60612, United States
Author contributions: Singh AK, Arruda JAL, Gudehithlu KP and Kraus M designed the experiments; Pancholi N, Patel J, Gudehithlu KP, Litbarg NO and Sethupathi P performed the experiments; Litbarg NO contributed new reagents/analytic tools; Singh AK, Arruda JAL, Gudehithlu KP and Pancholi N analyzed the data; Singh AK, Dunea G and Arruda JAL wrote the paper.
Correspondence to: Ashok K Singh, PhD, Stroger Hospital of Cook County, 637 South Wood St, Durand Bldg 2nd Floor, Chicago IL 60612, United States. singhashok@comcast.net
Telephone: +1-312-8644613  
Fax: +1-312-8649569
Received: September 6, 2008
Revised: January 29, 2009
Accepted: February 4, 2009
Published online: March 7, 2009
Abstract

AIM: To investigate the mechanism of liver regeneration induced by fusing the omentum to a small traumatic injury created in the liver. We studied three groups of rats. In one group the rats were omentectomized; in another group the omentum was left in situ and was not activated, and in the third group the omentum was activated by polydextran particles.

METHODS: We pre-activated the omentum by injecting polydextran particles and then made a small wedge wound in the rat liver to allow the omentum to fuse to the wound. We monitored the regeneration of the liver by determining the ratio of liver weight/body weight, by histological evaluation (including immune staining for cytokeratin-19, an oval cell marker), and by testing for developmental gene activation using reverse transcription polymerase chain reaction (RT-PCR).

RESULTS: There was no liver regeneration in the omentectomized rats, nor was there significant regeneration when the omentum was not activated, even though in this instance the omentum had fused with the liver. In contrast, the liver in the rats with the activated omentum expanded to a size 50% greater than the original, and there was histologically an interlying tissue between the wounded liver and the activated omentum in which bile ducts, containing cytokeratin-19 positive oval cells, extended from the wound edge. In this interlying tissue, oval cells were abundant and appeared to proliferate to form new liver tissue. In rats pre-treated with drugs that inhibited hepatocyte growth, liver proliferation was ongoing, indicating that regeneration of the liver was the result of oval cell expansion.

CONCLUSION: Activated omentum facilitates liver regeneration following injury by a mechanism that depends largely on oval cell proliferation.

Keywords: Cytokeratin; Foreign body; Growth factors; Oval cell; Progenitor cells