1 Liver stem cells, or even stem cells derived from other tissues, could potentially provide a source of
human hepatocytes for regeneration of the injured liver.3, 4 In particular, mesenchymal stem cells (MSCs), shown to be capable of in vitro differentiation into hepatocytes,5 were investigated as a possible source of hepatocytes for liver regeneration. In addition, it has been shown that secretion of trophic molecules by MSCs may favor regeneration following acute liver injury.6 In a previous study, we isolated a population of human adult liver stem cells (HLSCs) expressing MSC markers and certain embryonic and hepatic cell markers, and having multipotent differentiation capabilities and regenerative properties.7 However, the therapeutic potential of HLSCs and HLSC-conditioned medium (CM) in FLF
has not yet been evaluated. In this study we investigated SB203580 in vitro PS-341 ic50 the effect of HLSCs and HLSC-derived CM in a lethal model of liver injury induced by D-galactosamine (GalN) and lipopolysaccharide (LPS) in SCID mice. HLSCs were isolated from human cryopreserved normal hepatocytes and MSCs were obtained from Lonza (Basel, Switzerland) and were cultured as described in the online Supporting Information.7, 8 Detailed protocols for the preparation of CM from HLSCs or MSCs9 are provided in the online Supporting Information. CM, conditional medium; FLF, fulminant liver failure; GalN, D-galactosamine; HLSCs, human liver stem cells; LPS, lipopolysaccharide; MSCs, mesenchymal stem cells. The CM was analyzed
for specific proteins, using multiplex biometric immunoassay, Bioclarma (Bio-Plex Human Cytokine Assay; Bio-Rad Laboratories, Hercules, CA) and data were confirmed by enzyme-linked Succinyl-CoA immunosorbent assay (ELISA). Studies were approved by the University of Torino Ethics Committee and conducted in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals. Intramuscular injection of Zolazepam (0.2 mL/kg) and Xilazin (16 mg/kg) were used as anesthesia (40 µL/mouse). FLF was induced in male SCID mice (7-8 weeks old) (Charles River Laboratories, Milan, Italy), by intraperitoneal injection of GalN (600 mg/kg body weight) and LPS (125 ng per animal).10 Injection of GalN and LPS induced liver injury causing apoptosis and necrosis of hepatocytes with 100% lethality at 8 hours. Thirty minutes after GalN/LPS administration, mice received different treatments. The following groups were studied: group 1, FLF mice intravenously injected with vehicle alone (n = 18); group 2, healthy mice intraperitoneally injected with vehicle instead of GalN/LPS (n = 6); group 3, FLF mice intravenously injected with 2 × 106 HLSCs (n = 9, 3.3 × 105 cells given six times for a total number of 2 × 106); group 4, FLF mice intravenously injected with 2 × 106 MSCs (n = 6, 3.