Kasai Portoenterostomy at a Slightly Delayed Age and Native Liver Survival in Children With Biliary Atresia: Single Center Experience.

OBJECTIVES: We studied the modifiable prognostic factors that extend native liver survival at 2 years after Kasai portoenterostomy (KPE). METHODS: We reviewed hospital records of patients with neonatal cholestasis, with focus on infants diagnosed with biliary atresia in a tertiary care hospital between January, 2014 and May, 2021. We determined the association of outcome with clinical and laboratory variables. RESULTS: Infants who underwent KPE at a median (IQR) age of 76 (72-79) days had best outcomes, with minimal severe post-KPE complications and 2-year survival rate of 84.6%, compared to other infants (younger and older days at KPE). The median (IQR) weight at KPE in this group was 4.66 (4.2, 5.0) kg. CONCLUSION: In contrast to traditional recommendations, babies with median age at KPE of 76 days had superior native liver survival (84.6%) and reduced post-KPE complications, as compared to earlier KPE age. Nutritional status and weight of infant at KPE could be associated with this survival difference. This observation needs confirmation through multicentric prospective study.

Systemic Delivery of scAAV8-Encoded MiR-29a Ameliorates Hepatic Fibrosis in Carbon Tetrachloride-Treated Mice.

Fibrosis refers to the accumulation of excess extracellular matrix (ECM) components and represents a key feature of many chronic inflammatory diseases. Unfortunately, no currently available treatments specifically target this important pathogenic mechanism. MicroRNAs (miRNAs) are short, non-coding RNAs that post-transcriptionally repress target gene expression and the development of miRNA-based therapeutics is being actively pursued for a diverse array of diseases. Because a single miRNA can target multiple genes, often within the same pathway, variations in the level of individual miRNAs can potently influence disease phenotypes. Members of the miR-29 family, which include miR-29a, miR-29b and miR-29c, are strong inhibitors of ECM synthesis and fibrosis-associated decreases in miR-29 have been reported in multiple organs. We observed downregulation of miR-29a/b/c in fibrotic livers of carbon tetrachloride (CCl4) treated mice as well as in isolated human hepatocytes exposed to the pro-fibrotic cytokine TGF-ß. Importantly, we demonstrate that a single systemic injection of a miR-29a expressing adeno-associated virus (AAV) can prevent and even reverse histologic and biochemical evidence of fibrosis despite continued exposure to CCl4. The observed therapeutic benefits were associated with AAV transduction of hepatocytes but not hepatic stellate cells, which are the main ECM producing cells in fibroproliferative liver diseases. Our data therefore demonstrate that delivery of miR-29 to the hepatic parenchyma using a clinically relevant gene delivery platform protects injured livers against fibrosis and, given the consistent fibrosis-associated downregulation of miR-29, suggests AAV-miR-29 based therapies may be effective in treating a variety of fibroproliferative disorders.

Contribution of extrahepatic small cells resembling small hepatocyte-like progenitor cells to liver mass maintenance in transplantation model of retrorsine-pretreated liver.

PURPOSE: Retrorsine selectively inhibits hepatocyte proliferation and following liver injury evokes small hepatocyte-like progenitor cells. The aim of this study is to find out whether endogenous extrahepatic cells contribute to small hepatocyte-like progenitor cells after retrorsine treatment. METHODS: Wild-type Lewis rat liver exposed to retrorsine was transplanted into GFP transgenic Lewis rat. GFP positive, albumin-producing polygonal cells were expected as reciepient-derived hepatocyte-like cells. RESULTS: Four weeks after transplantation of 50% volume of retrorsine-pretreated liver, the rate of GFP positive hepatocyte-like cells was 0.02365%. Majority of these cells resided as single cells and their cell size was significantly larger than that of normal hepatocytes (mean cell size; 799.4 um(2) vs. 451.3 um(2), p<0.0001). At eight weeks, clusters of GFP positive small-size albumin-producing cells appeared and occupied 0.00759% of hepatocytes. The morphology of these cells was similar to that of small hepatocyte-like progenitor cells, 12.5% of them were Ki67 positive, majority of them were negative for CYP1A2 staining, and some clusters contained larger cells indicating further maturation. CONCLUSION: Endogenous extrahepatic cells can form a cluster of small cells resembling small hepatocyte-like progenitor cells in a transplanted retrorsine-pretreated liver. The contribution of extrahepatic cells to liver mass maintenance is quite low and its importance is unclear.

Transactivation of miR-34a by p53 broadly influences gene expression and promotes apoptosis.

The p53 tumor suppressor protein is a critical regulator of the cellular response to cancer-initiating insults such as genotoxic stress. In this report, we demonstrate that microRNAs (miRNAs) are important components of the p53 transcriptional network. Global miRNA expression analyses identified a cohort of miRNAs that exhibit p53-dependent upregulation following DNA damage. One such miRNA, miR-34a, is commonly deleted in human cancers and, as shown here, frequently absent in pancreatic cancer cells. Characterization of the miR-34a primary transcript and promoter demonstrates that this miRNA is directly transactivated by p53. Expression of miR-34a causes dramatic reprogramming of gene expression and promotes apoptosis. Much like the known set of p53-regulated genes, miR-34a-responsive genes are highly enriched for those that regulate cell-cycle progression, apoptosis, DNA repair, and angiogenesis. Therefore, it is likely that an important function of miR-34a is the modulation and fine-tuning of the gene expression program initiated by p53.