BASIC STUDIES Transdi¡erentiation of adipose-derived stem cells into hepatocytes: a new approach James Lue 1 , Guiting Lin 2 , Hongxiu Ning 2 , Anming Xiong 3 , Ching-Shwun Lin 2 and Jeffrey S. Glenn 3 1 Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology, and Nutrition, Stanford University, Palo Alto, CA, USA 2 Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, San Francisco, CA, USA 3 Department of Medicine, Division of Gastroenterology, Stanford University. Alway Building, CA, USA Keywords adipose – hepatic differentiation – hepatocyte – liver – mesenchymal stem cell Correspondence James Lue, MD, Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology, and Nutrition, Stanford University, 750 Welch Road, Suite 116, Palo Alto, CA, USA Tel: 11 650 723 5070 Fax: 1650 498 5608 e-mail: jluemd@gmail.com Received 28 August 2009 Accepted 9 February 2010 DOI:10.1111/j.1478-3231.2010.02231.x Abstract Background: Several studies have demonstrated techniques in differentiating human adipose-derived stem cells (hADSCs) into hepatocytes. Unfortunately, transdifferentiation is inefficient, and the function of these induced hepato- cyte-like cells (which we termed ‘iHeps’) is low compared with that of real hepatocytes. Aims: We aimed to identify transcriptional deficiencies in iHeps that are critical to hepatocyte development, which may provide insights into improving the efficiency of transdifferentiation. Methods: hADSCs were differentiated into iHeps, and iHeps were assayed for hepatocyte-like activity. iHeps were then screened for expression of several growth factors, receptors and transcription factors (TFs) critical to liver development using reverse transcription-polymerase chain reaction (RT-PCR). Deficient TFs were trans- duced into hADSCs and hepatocyte function was reassessed after hepatic differentiation. Results: Differentiation of hADSCs into iHeps resulted in the upregulation of hepatic proteins. However, the levels of expression of hepatocyte-specific proteins in these iHeps were well below those of Huh 7.5 hepatoma cells, used in comparison. Five developmental TFs were notably absent on the RT-PCR screen. Lentiviral transduction of these TFs into hADSCs followed by culture in hepatocyte induction medium resulted in increased albumin expression compared with untransduced hADSCs treated in a parallel fashion. Conclusions: These five missing TFs are known to regulate hepatocyte differentiation and some are required to establish the competence of the foregut endoderm. Presumably due to their mesenchymal lineage, hADSCs do not express these endodermal TFs and are not fully competent to respond to critical developmental signals. Supplementation of these TFs may induce competency and enhance the differentiation of hADSCs into hepatocytes. In recent years, stem cells have generated great interest because of their potential for therapeutic use. Because of the vast shortage of organ donors, researchers have long been in search of alternatives to whole-organ transplan- tation. Embryonic stem cells (ESCs) are a potentially powerful means of stem cell therapy, but their tendency to form teratomas and the ethical concerns regarding their use remain unresolved. Low passage adult stem cells do not form teratomas and their procurement raises no ethical dilemmas (1). Cell-based therapies developed using adult stem cells have the added advantage of potentially not requiring immunosuppression after auto- logous transplantation. Adult adipose tissue is derived from embryonic me- senchyme, and a stem cell population within the adipose stromal compartment has been identified and termed adipose tissue-derived stem cells (ADSCs). Similar to bone marrow-derived mesenchymal stem cells (MSCs), ADSCs are an abundant and readily accessible source of adult MSCs that may be used for cell-based therapy and tissue engineering. ADSCs have the ability to differentiate into several different tissue lineages, and in recent years, several groups have been able to grow ADSCs in conditions encouraging their differentiation toward the hepatocyte lineage (2–9). These cells have been reported to acquire hepatocyte-specific synthetic functions, such as albumin and urea production, as well as detoxification activity, such as drug metabolism and ammonia clearance. Transplantation of these cells into various animal models of liver failure has demonstrated recovery of liver function and improvement in markers of liver injury. However, the ability of MSCs to transdifferentiate into endodermal tissues remains a controversial topic. Zemel Liver International (2010) c  2010 John Wiley & Sons A/S 913 Liver International ISSN 1478-3223