INHIBITION OF HEPATIC SPARC (SECRETED PROTEIN ACIDIC AND RICH IN CYSTEINE) EXPRESSION FOR THE TREATMENT OF EXPERIMENTAL CIRRHOSIS

CAMINO A, SILVA M, PRADA F, PODHAJCER O, MAZZOLINI G

Baltimore

Congreso; 9th Annual Meeting of the American Society of Gene Therapy; 2006

American Society of Gene Therapy

Introduction: SPARC is a 42-kDa matricellular glycoprotein involved in many biological process including cell adhesion, differentiation and proliferation. SPARC is also expressed by activated hepatic stellate cells suggesting its involvement in liver fibrogenesis. Aim: to determine whether liver gene delivery of a SPARC antisense mRNA (AdasSPARC) would prevent hepatic fibrosis in an animal model. M&M: Intraperitoneal injection of TAA was used to induce cirrhosis in Sprague-Dawley rats. Animals received injections of a recombinant adenovirus encoding a SPARC antisense mRNA (AdasSPARC) or a control adenovirus encoding b-galactosidase gene (Adbgal) via the tail vein at the beginning of TAA administration. At day 7 the animals received a second dose directly into the liver by laparotomy. Antifibrotic effects of SPARC inhibition were assessed by histological examination, quantification of extracellular matrix deposition and activation of hepatic stellate cells (HSC). Results: The percentage of fibrosis area in the liver by image analysis of Sirius red staining was decreased in AdasSPARC treated animals (11%± 0.04%) in comparison with animals treated with Adbgal or saline (27% ± 0.15% and 28%± 0.16 %, respectively). Quantification of hepatic hydroxyproline confirmed that a SPARC antisense mRNA expression in the liver attenuated collagen deposition. In the livers of rats treated with saline or Adbgal, no significant prevention in the fibrosis score was observed (F3-F4). Contrarily, only slight to moderate fibrosis was observed in the animals that received AdasSPARC (F1-F2). The total Knodell score of saline and Adbgal treated rats was greater than those of AdasSPARC treated rats (13/22, 10/22 and 6/22, respectively). By immunohistochemistry analysis, SPARC protein was highly expressed on liver tissue from control rats and significant inhibition was observed in AdasSPARC treated animals. The number of cells positive for a-smooth muscle actin was significantly reduced in animals after the administration of AdasSPARC. Conclusions: Taken together, our results provide in vivo evidence that adenovirus-mediated gene transfer of a SPARC antisense mRNA in the liver ameliorates fibrosis and necroinflammatory activity induced by TAA.