Fine-needle aspiration biopsy in the monitoring of liver allografts. I. Correlation between aspiration biopsy and core biopsy in experimental pig liver allografts

Preparation of immunogen-reduced and biocompatible extracellular matrices from porcine liver

Decellularized biologic matrices are plausible biomedical materials for the bioengineering in liver transplantation. However, one of the concerns for safe medical application is the lack of objective assessment of the immunogen within the materials and the in vivo immune responses to the matrices. The purpose of this study was the production of immunogen-reduced and biocompatible matrices from porcine liver. In the present study, 0.1% SDS solution was effective for removing DNA fragments and sequences encoding possible immunogenic and viral antigens within the matrices. The PCR analysis showed that galactose-α-1,3 galactose β-1,4-N-acetylglucosamine (1,3 gal), swine leukocyte antigen (SLA), and porcine endogenous retrovirus (PERV) were completely removed in the matrices. Collagen and glycosaminoglycans (GAGs) were preserved over 63%-71%, respectively, compared to those of native liver. The implanted decellularized tissues showed minimal host responses and naturally degraded within 10 weeks. In this study, we produced immunogen-reduced and biocompatible extracellular matrices from porcine liver. Although future investigations would be required to determine the mechanism of the host reaction, this study could provide useful information of porcine liver-derived biologic matrices for liver researches.

Intrahepatic Detection of FOXP3 Gene Expression After Liver Transplantation Using Minimally Invasive Aspiration Biopsy

Intragraft accumulation of Forkhead box P3 (FOXP3)-positive regulatory T cells (Treg) is associated with local suppression of alloresponses in transplantation models. In the current study, the utility of the minimally invasive fine needle aspiration biopsy for the intragraft detection of FOXP3 and interferon (IFN)-gamma mRNA expression was investigated in clinical liver transplantation (LTx). Intragraft FOXP3 increased within the first year after LTx, but not in blood. Elevated FOXP3, but not IFN-gamma expression, in the liver was observed after hepatitis C virus (HCV) reinfection and after a previous episode of acute rejection. These data show the feasibility of aspiration biopsy for intragraft monitoring of gene expression. Intrahepatic FOXP3 levels are associated with HCV reinfection, a history of acute rejection, and increased within the first year after LTx. Differences in gene expression between the graft and blood underline the importance of local immune monitoring.

Flowcytometric quantitation of hepatitis B viral antigens in hepatocytes from regular and fine-needle biopsies

The aim of the study was to investigate the use of flow cytometry, as an alternative for immunohistochemistry, for the detection of viral antigens in the liver of patients with chronic hepatitis B virus (HBV) infection. Hepatocytes were obtained from regular- and fine-needle biopsy from HBV positive (n=17) and negative (n=7) patients and quantified by flow cytometry for intracellular hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg). Number of HBsAg positive hepatocytes ranged from 0 to 83%. A significant correlation was found between the percentage of infected hepatocytes and the intracellular expression level of HBsAg (R=0.841, p<0.001). The specificity and sensitivity of flow cytometry was similar to immunohistochemistry. Of the patients on anti-viral treatment with undetectable serum HBV DNA (<400 copies/ml), two had high HBsAg expression in the liver. HBcAg staining was found in 3 out of 15 patients, with 2-3% positive hepatocytes. The results obtained with fine-needle aspiration biopsy (n=12) were comparable to regular biopsy. In conclusion, flowcytometric quantitation of HBV antigens is sensitive and provides relevant information on the course of infection. The minimally invasive fine-needle biopsy provides a useful alternative for regular-needle biopsy for monitoring intrahepatic antiviral responses during therapy.

Fine-needle aspiration biopsy in the monitoring of liver allografts

The diagnosis of acute liver allograft rejection is difficult, as clinical signs or liver function tests are too unspecific. The diagnosis is mainly based on biopsy histology. However, the liver core biopsy may be associated with complications. The fine-needle aspiration biopsy (FNAB) method, originally developed for the monitoring of renal transplants, is a reliable and atraumatic technique to diagnose acute cellular rejection of liver allografts. FNAB makes it possible to quantity the inflammation associated with rejection, and to monitor the response to anti-rejection therapy. Additional information is received from changes in liver parenchymal cells indicating tissue damage and/or possible hepatotoxic effects of the drugs used. In addition, FNAB may be helpful in differential diagnosis of infections, cholestasis or other complications. A good correlation between FNAB findings of acute liver rejection and histology has been reported. However, histological examination is needed to diagnose chronic rejection. Several liver transplant centres now use FNAB technology as a routine diagnostic tool.