Diarmaid D. Houlihan

Critical review of clinical trials of bone marrow stem cells in liver disease.

Morbidity and mortality from cirrhosis is increasing rapidly in the Western world. Currently the only effective treatment is liver transplantation, an increasingly limited and expensive resource. Consequently, there has been great hope that stem cells may offer new therapeutic approaches in the management of liver disease. In this review we critically appraise the 11 published clinical studies of bone marrow stem cells in liver disease, and focus on the unresolved issues regarding their role. We outline the different mechanisms by which stem cells may impact on liver disease, as well as highlight the importance of the type of stem cell chosen. There are multiple different stem cell populations that have, in rodent studies, been shown to have differing effects on liver regeneration and fibrogenesis/degradation. Thus, choice of cell should reflect the desired or expected mechanism of action. The importance, and methods, of studying the fate of stem cells infused in clinical studies is emphasized as we seek to translate observations in rodents into the clinical setting. Finally, we discuss which cohorts of patients with liver disease would benefit from stem cell therapy, as well as establish minimum criteria for future clinical trials of stem cells.

Presence and severity of non-alcoholic fatty liver disease in a large prospective primary care cohort.

BACKGROUND & AIMS Non-alcoholic fatty liver disease (NAFLD) is a common cause of abnormal LFTs in primary care, but there are no data defining its contribution nor reporting the range of NAFLD severity in this setting. This study seeks to calculate the range of disease severity of NAFLD in a primary care setting. METHODS Adult patients with incidental abnormal LFTs, in the absence of a previous history, or current symptoms/signs of liver disease were prospectively recruited from eight primary care practices in Birmingham. NAFLD was diagnosed as fatty liver on ultrasound, negative serological liver aetiology screen, and alcohol consumption ≤30 and ≤20 g/day in males and females, respectively. The NAFLD Fibrosis Score (NFS) was calculated to determine the presence or absence of advanced liver fibrosis in subjects identified with NAFLD. RESULTS Data from 1118 adult patients were analysed. The cause of abnormal LFTs was identified in 55% (614/1118) of subjects, with NAFLD (26.4%; 295/1118) and alcohol excess (25.3%; 282/1118) accounting for the majority. A high NFS (>0.676) suggesting the presence of advanced liver fibrosis was found in 7.6% of NAFLD subjects, whereas 57.2% of NAFLD patients had a low NFS (<-1.455) allowing advanced fibrosis to be confidently excluded. CONCLUSIONS NAFLD is the commonest cause of incidental LFT abnormalities in primary care (26.4%), of whom 7.6% have advanced fibrosis as calculated by the NFS. This study is the first of its kind to highlight the burden of NAFLD in primary care and provide data on disease severity in this setting.

Isolation of mouse mesenchymal stem cells on the basis of expression of Sca-1 and PDGFR-α.

Platelet-derived growth factor receptor α (PDGFR-α) and stem cell antigen 1 (Sca-1) have recently been identified as selective markers of mouse mesenchymal stem cells (MSCs). PDGFR-α+Sca-1+ (PαS) MSCs have augmented growth potential and robust tri-lineage differentiation compared with standard culture-selected MSCs. In addition, the selective isolation of PαS MSCs avoids cellular contamination that can complicate other methods. Here we describe in detail our protocol to isolate PαS MSCs using flow cytometry. In brief, the tibia and femora are isolated and crushed using a pestle and mortar. The crushed bones are then chopped and incubated for 1 h at 37 °C in 20 ml of DMEM containing 0.2% (wt/vol) collagenase. The cell suspension is filtered before red blood cell lysis and incubated with the following antibodies: allophycocyanin (APC)-conjugated PDGFR-α, FITC-conjugated Sca-1, phycoerythrin (PE)-conjugated CD45 and Ter119. Appropriate gates are constructed on a cell sorter to exclude dead cells and lineage (CD45+Ter-119+)-positive cells. Approximately 10,000 PαS MSCs may then be isolated per mouse. The total protocol takes ∼7 h to complete.

Safety and efficacy of liraglutide in patients with type 2 diabetes and elevated liver enzymes: Individual patient data meta-analysis of the LEAD program

Non‐alcoholic fatty liver disease has reached epidemic proportions in type 2 diabetes (T2D). Glucagon‐like peptide‐1 analogues are licensed in T2D, yet little data exist on efficacy and safety in liver injury.

LNGFR+THY-1+VCAM-1hi+ Cells Reveal Functionally Distinct Subpopulations in Mesenchymal Stem Cells

Summary Human mesenchymal stem cells (hMSCs), which conventionally are isolated based on their adherence to plastic, are heterogeneous and have poor growth and differentiation, limiting our ability to investigate their intrinsic characteristics. We report an improved prospective clonal isolation technique and reveal that the combination of three cell-surface markers (LNGFR, THY-1, and VCAM-1) allows for the selection of highly enriched clonogenic cells (one out of three isolated cells). Clonal characterization of LNGFR+THY-1+ cells demonstrated cellular heterogeneity among the clones. Rapidly expanding clones (RECs) exhibited robust multilineage differentiation and self-renewal potency, whereas the other clones tended to acquire cellular senescence via P16INK4a and exhibited frequent genomic errors. Furthermore, RECs exhibited unique expression of VCAM-1 and higher cellular motility compared with the other clones. The combination marker LNGFR+THY-1+VCAM-1hi+ (LTV) can be used selectively to isolate the most potent and genetically stable MSCs.

Systematic review: pentoxifylline for the treatment of severe alcoholic hepatitis.

Acute alcoholic hepatitis (AH) is a severe manifestation of alcoholic liver disease with a grave prognosis. Pentoxifylline, an oral antitumour necrosis factor agent, has been reported to reduce mortality and incidence of hepatorenal syndrome (HRS) in severe alcoholic hepatitis (SAH).

Prospective isolation of murine and human bone marrow mesenchymal stem cells based on surface markers

Mesenchymal stem cells (MSCs) are currently defined as multipotent stromal cells that undergo sustained in vitro growth and can give rise to cells of multiple mesenchymal lineages, such as adipocytes, chondrocytes, and osteoblasts. The regenerative and immunosuppressive properties of MSCs have led to numerous clinical trials exploring their utility for the treatment of a variety of diseases (e.g., acute graft-versus-host disease, Crohns disease, multiple sclerosis, osteoarthritis, and cardiovascular diseases including heart failure and myocardial infarction). On the other hand, conventionally cultured MSCs reflect heterogeneous populations that often contain contaminating cells due to the significant variability in isolation methods and the lack of specific MSC markers. This review article focuses on recent developments in the MSC research field, with a special emphasis on the identification of novel surface markers for the in vivo localization and prospective isolation of murine and human MSCs. Furthermore, we discuss the physiological importance of MSC subtypes in vivo with specific reference to data supporting their contribution to HSC niche homeostasis. The isolation of MSCs using selective markers (combination of PDGFRα and Sca-1) is crucial to address the many unanswered questions pertaining to these cells and has the potential to enhance their therapeutic potential enormously.

Renal function in patients undergoing transplantation for nonalcoholic steatohepatitis cirrhosis: Time to reconsider immunosuppression regimens?

Nonalcoholic fatty liver disease is an independent risk factor for chronic kidney injury (CKI), yet the impact of liver transplantation (LT) on renal function in this at‐risk group is not known. We compared the post‐LT renal function of patients with nonalcoholic steatohepatitis (NASH) and a matched comparison group. Forty‐eight consecutive patients who underwent transplantation for NASH between 2000 and 2008 in a single UK center were compared to non‐NASH patients who were matched by age, sex, Model for End‐Stage Liver Disease score, and estimated glomerular filtration rate (eGFR; calculated with the Modification of Diet in Renal Disease formula). In comparison with non‐NASH patients, NASH patients had a significantly lower eGFR 3 months after LT (eGFR difference = 8.85 mL/minute/1.73 m2, 95% confidence interval = 2.93‐14.77). After adjustments for the effects of the body mass index, tacrolimus levels, diabetes mellitus, hypertension, and hepatocellular carcinoma, the difference between the groups remained significant 3 months after LT (P = 0.001). These data were then analyzed at numerous time points after LT (6, 12, and 24 months), and the time did not significantly affect the difference between the groups (P = 0.17). Within 2 years, 31.2% of the NASH patients (15/48) had developed stage IIIb CKI, whereas only 8.3% of the non‐NASH patients (4/48) did (P = 0.009). In conclusion, this study has identified NASH as an independent risk factor for renal dysfunction after LT. Renal‐sparing immunosuppression regimens should be considered at the time of LT to reduce the development of kidney injury in NASH patients. The optimization of such regimens requires a prospective study. Liver Transpl 17:1292–1298, 2011.

Development of Hepatocellular Carcinoma in a Murine Model of Nonalcoholic Steatohepatitis Induced by Use of a High-Fat/Fructose Diet and Sedentary Lifestyle

Obesity is increasingly prevalent, strongly associated with nonalcoholic liver disease, and a risk factor for numerous cancers. Here, we describe the liver-related consequences of long-term diet-induced obesity. Mice were exposed to an extended obesity model comprising a diet high in trans-fats and fructose corn syrup concurrent with a sedentary lifestyle. Livers were assessed histologically using the nonalcoholic fatty liver disease (NAFLD) activity score (Kleiner system). Mice in the American Lifestyle-Induced Obesity Syndrome (ALIOS) model developed features of early nonalcoholic steatohepatitis at 6 months (mean NAFLD activity score = 2.4) and features of more advanced nonalcoholic steatohepatitis at 12 months, including liver inflammation and bridging fibrosis (mean NAFLD activity score = 5.0). Hepatic expression of lipid metabolism and insulin signaling genes were increased in ALIOS mice compared with normal chow-fed mice. Progressive activation of the mouse hepatic stem cell niche in response to ALIOS correlated with steatosis, fibrosis, and inflammation. Hepatocellular neoplasms were observed in 6 of 10 ALIOS mice after 12 months. Tumors displayed cytological atypia, absence of biliary epithelia, loss of reticulin, alteration of normal perivenular glutamine synthetase staining (absent or diffuse), and variable α-fetoprotein expression. Notably, perivascular tumor cells expressed hepatic stem cell markers. These studies indicate an adipogenic lifestyle alone is sufficient for the development of nonalcoholic steatohepatitis, hepatic stem cell activation, and hepatocarcinogenesis in wild-type mice.

Purified Human Dental Pulp Stem Cells Promote Osteogenic Regeneration

Human dental pulp stem/progenitor cells (hDPSCs) are attractive candidates for regenerative therapy because they can be easily expanded to generate colony-forming unit–fibroblasts (CFU-Fs) on plastic and the large cell numbers required for transplantation. However, isolation based on adherence to plastic inevitably changes the surface marker expression and biological properties of the cells. Consequently, little is currently known about the original phenotypes of tissue precursor cells that give rise to plastic-adherent CFU-Fs. To better understand the in vivo functions and translational therapeutic potential of hDPSCs and other stem cells, selective cell markers must be identified in the progenitor cells. Here, we identified a dental pulp tissue–specific cell population based on the expression profiles of 2 cell-surface markers LNGFR (CD271) and THY-1 (CD90). Prospectively isolated, dental pulp–derived LNGFRLow+THY-1High+ cells represent a highly enriched population of clonogenic cells—notably, the isolated cells exhibited long-term proliferation and multilineage differentiation potential in vitro. The cells also expressed known mesenchymal cell markers and promoted new bone formation to heal critical-size calvarial defects in vivo. These findings suggest that LNGFRLow+THY-1High+ dental pulp–derived cells provide an excellent source of material for bone regenerative strategies.