Reversal Of Fibrosis Research Articles

Effects of JAK1/2 inhibition on bone marrow stromal cells of myeloproliferative neoplasm (MPN) patients and healthy individuals.

Philadelphia-negative myeloproliferative neoplasms (MPNs) commonly share hyperactive JAK-STAT signaling affecting hematopoietic stem cells (HSC) and their progeny. The JAK1/2 inhibitor Ruxolitinib has remarkable clinical efficacy, including spleen reduction, improvement of constitutional symptoms, and bone marrow (BM) fibrosis reversal. Whether this is due to inhibition of JAK2-mutated HSC only, or whether Ruxolitinib also affects BM stroma is not known. This study investigated potential effects of Ruxolitinib on BM mesenchymal stromal cells (MSC), which are not only major regulators of hematopoiesis but also contribute to fibrosis, from 10 healthy donors and 7 JAK2V617F -positive MPN patients. Ruxolitinib moderately inhibited the growth of healthy donor MSC (HD-MSC) and MSC from JAK2V617F+ MPN patients (P-MSC) in short- and long-term assays. The clonogenic potential of HD-MSC was not affected by Ruxolitinib. JAK-STAT signaling, however, was markedly inhibited in both HD-MSC and P-MSC, the latter of which showed higher expression of fibrosis-associated and hematopoiesis-maintenance genes. Moreover, Ruxolitinib reduced MSC secretion of MCP-1 and IL-6. Ruxolitinib affected JAK2 signaling in MSC at clinically relevant doses, which is likely to contribute to the normalization of the inflammatory milieu in MPNs. Thus, combined HSC and stroma-directed interventions have the potential to improve constitutional symptoms and reduce stromal proliferation in MPNs.

Postnatal Organogenesis by Transdifferentiation

Transdifferentiation is a physiological backup mechanism and alternative to stem‐cell‐mediated organ regeneration. In adult mammals, findings of transdifferentiation have been limited to replenishing lost cells in preexisting structures, i.e., in the presence of a fully developed scaffold and niche. Here we show that hepatocytes in the adult liver can transdifferentiate to build a structure that failed to form in development––the biliary system in mice that mimic the hepatic phenotype of human Alagille syndrome. The bile ducts forming the new biliary system are fully functional as evidenced by reversal of cholestasis, liver injury and liver fibrosis. Our results reveal the potential of mammalian transdifferentiation and may inform efforts to build organs containing a complex tubular system.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Chronic hepatitis C: achievement, challenge and strategy to eliminate as a public health threat

The use of direct-acting antiviral agents (DAAs) in the treatment of chronic hepatitis C and its approval in China applying the goal proposed by the World Health Organization is an important step towards eliminating viral hepatitis as public health threat by 2030. However, we also need to create a model that is suitable and short duration therapy for the Chinese patients. On the other hand, it is also essential to study the reverse hepatic fibrosis and the emerging problems of hepatitis C-related liver cancer.

Trichostatin A inhibits the activation of Hepatic stellate cells by Increasing C/EBP-\u03b1 Acetylation in vivo and in vitro

Reversal of activated hepatic stellate cells (HSCs) to a quiescent state and apoptosis of activated HSCs are key elements in the reversion of hepatic fibrosis. CCAAT/enhancer binding protein α (C/EBP-α) has been shown to inhibit HSC activation and promote its apoptosis. This study aims to investigate how C/EBP-α acetylation affects the fate of activated HSCs. Effects of a histone deacetylation inhibitor trichostatin A (TSA) on HSC activation were evaluated in a mouse model of liver fibrosis caused by carbon tetrachloride (CCl4) intoxication. TSA was found to ameliorate CCl4-induced hepatic fibrosis and improve liver function through increasing the protein level and enhancing C/EBP-α acetylation in the mouse liver. C/EBP-α acetylation was determined in HSC lines in the presence or absence of TSA, and the lysine residue K276 was identified as a main acetylation site in C/EBP-α protein. C/EBP-α acetylation increased its stability and protein level, and inhibited HSC activation. The present study demonstrated that C/EBP-α acetylation increases the protein level by inhibiting its ubiquitination-mediated degradation, and may be involved in the fate of activated HSCs. Use of TSA may confer an option in minimizing hepatic fibrosis by suppressing HSC activation, a key process in the initiation and progression of hepatic fibrosis.

Altered global microRNA expression in hepatic stellate cells LX-2 by angiotensin-(1–7) and miRNA-1914-5p identification as regulator of pro-fibrogenic elements and lipid metabolism

The development of new therapeutic strategies to control or reverse hepatic fibrosis requires thorough knowledge about its molecular and cellular basis. It is known that the heptapeptide angiotensin-(1-7) [ang-(1-7)] can reduce hepatic fibrosis and steatosis in vivo; therefore, it is important to uncover the mechanisms regulating its activity and cellular model of investigation. Ang-(1-7) is a peptide of the renin-angiotensin system (RAS), and here we investigated its modulatory effect on the expression pattern of microRNAs (miRNAs) in hepatic stellate cells (HSCs) LX-2, which transdifferentiate into fibrogenic and proliferative cells. We compared the miRNA profiles between quiesced, activated and ang-(1-7)-treated activated HSCs to identify miRNAs that may regulate their transdifferentiation. Thirteen miRNAs were pointed, and cellular and molecular analyses identified miRNA-1914-5p as a molecule that contributes to the effects of ang-(1-7) on lipid metabolism and on the pro-fibrotic environment control. In our cellular model, we also analyzed the regulators of fatty acid metabolism. Specifically, miRNA-1914-5p regulates the expression of malonyl-CoA decarboxylase (MLYCD) and phosphatidic acid phosphohydrolase (PAP or Lipin-1). Additionally, Lipin-1 was closely correlated with mRNA expression of peroxisome proliferator-activated receptors (PPAR)-α and -γ, which also contribute to lipid homeostasis and to the reduction of TGF-β1 expression. These findings provide a novel link between RAS and lipid metabolism in controlling HSCs activation.

An Open-label Randomized Clinical Study to Compare the Effects of a Nutritional Supplement versus Vitamin E on Fibroscan Score in Nonalcoholic Steatohepatitis (NASH) Patients

Background: Despite the benefit of lifestyle changes, there is no standard treatment for Fibrotic NASH. However the concept of reversibility of liver fibrosis and cirrhosis with various natural biologically active compounds and antioxidant micro-nutrients is not new. Aim: The aim of this study was to compare effectiveness of Viusid® (a nutritional supplement) and Vitamin E in reducing steatosis and liver fibrosis score in patients with fibrotic NASH. Methods: 52 patients diagnosed with nondiabetic and noncirrhotic NASH on liver fibroscan were divided into 2 groups randomly and given Viusid® 3 sachets daily to 25 patients or Vitamin E 800 IU daily to 27 patients along with a hypocaloric diet and exercise for 3 months. Results: After 3 months treatment with Viusid®, as compared with Vitamin E, was associated with a significant reduction of both mean steatosis score (CAP value reduces from 286±16.3 to 208±18.5 dB/m in Viusid® group vs. from 278±14.4 to 253±12.1 dB/m in Vitamin E group; p 0.00001). Conclusions: Viusid® was superior to Vitamin E in reducing steatosis & fibrosis score in nondiabetic and noncirrhotic NASH patients. However, further large scale trial is needed to better assess the value of Viusid® for fibrotic NASH management.

IL-4 Receptor Alpha Signaling through Macrophages Differentially Regulates Liver Fibrosis Progression and Reversal

Chronic hepatitis leads to liver fibrosis and cirrhosis. Cirrhosis is a major cause of worldwide morbidity and mortality. Macrophages play a key role in fibrosis progression and reversal. However, the signals that determine fibrogenic vs fibrolytic macrophage function remain ill defined. We studied the role of interleukin-4 receptor α (IL-4Rα), a potential central switch of macrophage polarization, in liver fibrosis progression and reversal. We demonstrate that inflammatory monocyte infiltration and liver fibrogenesis were suppressed in general IL-4Rα−/− as well as in macrophage-specific IL-4Rα−/− (IL-4RαΔLysM) mice. However, with deletion of IL-4RαΔLysM spontaneous fibrosis reversal was retarded. Results were replicated by pharmacological intervention using IL-4Rα-specific antisense oligonucleotides. Retarded resolution was linked to the loss of M2-type resident macrophages, which secreted MMP-12 through IL-4 and IL-13-mediated phospho-STAT6 activation. We conclude that IL-4Rα signaling regulates macrophage functional polarization in a context-dependent manner. Pharmacological targeting of macrophage polarization therefore requires disease stage-specific treatment strategies. Research in ContextAlternative (M2-type) macrophage activation through IL-4Rα promotes liver inflammation and fibrosis progression but speeds up fibrosis reversal. This demonstrates context dependent, opposing roles of M2-type macrophages. During reversal IL-4Rα induces fibrolytic MMPs, especially MMP-12, through STAT6. Liver-specific antisense oligonucleotides efficiently block IL-4Rα expression and attenuate fibrosis progression.

Serelaxin as a novel therapeutic opposing fibrosis and contraction in lung diseases.

The most common therapies for asthma and other chronic lung diseases are anti-inflammatory agents and bronchodilators. While these drugs oppose disease symptoms, they do not reverse established structural changes in the airways and their therapeutic efficacy is reduced with increasing disease severity. The peptide hormone, relaxin, is a Relaxin Family Peptide Receptor 1 (RXFP1) receptor agonist with unique combined effects in the lung that differentiates it from these existing therapies. Relaxin has previously been reported to have cardioprotective effects in acute heart failure as well anti-fibrotic actions in several organs. This review focuses on recent experimental evidence of the beneficial effects of chronic relaxin treatment in animal models of airways disease demonstrating inhibition of airway hyperresponsiveness and reversal of established fibrosis, consistent with potential therapeutic benefit. Of particular interest, accumulating evidence demonstrates that relaxin can also acutely oppose contraction by reducing the release of mast cell-derived bronchoconstrictors and by directly eliciting bronchodilation. When used in combination, chronic and acute treatment with relaxin has been shown to enhance responsiveness to both glucocorticoids and β2-adrenoceptor agonists respectively. While the mechanisms underlying these beneficial actions remain to be fully elucidated, translation of these promising combined preclinical findings is critical in the development of relaxin as a novel alternative or adjunct therapeutic opposing multiple aspects of airway pathology in lung diseases.

Upregulated galectin-3 is not a critical disease mediator of cardiomyopathy induced by β2-adrenoceptor overexpression.

Preclinical studies have demonstrated that anti-galectin-3 (Gal-3) interventions are effective in attenuating cardiac remodeling, fibrosis, and dysfunction. We determined, in a transgenic (TG) mouse model of fibrotic cardiomyopathy, whether Gal-3 expression was elevated and whether Gal-3 played a critical role in disease development. We studied mice with fibrotic cardiomyopathy attributable to cardiac overexpression of human β2-adrenoceptors (β2-TG). Cardiac expression levels of Gal-3 and fibrotic or inflammatory genes were determined. The effect of Gal-3 inhibition in β2-TG mice was studied by treatment with Gal-3 inhibitors ( N-acetyllactosamine and modified citrus pectin) or by deletion of Gal-3 through crossing β2-TG and Gal-3 knockout mice. Changes in cardiomyopathy phenotypes were assessed by echocardiography and biochemical assays. In β2-TG mice at 3, 6, and 9 mo of age, upregulation of Gal-3 expression was observed at mRNA (~6- to 15-fold) and protein (~4- to 8-fold) levels. Treatment of β2-TG mice with N-acetyllactosamine (3 wk) or modified citrus pectin (3 mo) did not reverse cardiac fibrosis, inflammation, and cardiomyopathy. Similarly, Gal-3 gene deletion in β2-TG mice aged 3 and 9 mo did not rescue the cardiomyopathy phenotype. In conclusion, the β2-TG model of cardiomyopathy showed a robust upregulation of Gal-3 that correlated with disease severity, but Gal-3 inhibitors or Gal-3 gene deletion had no effect in halting myocardial fibrosis, remodeling, and dysfunction. Gal-3 may not be critical for cardiac fibrogenesis and remodeling in this cardiomyopathy model. NEW & NOTEWORTHY We showed a robust upregulation of cardiac galectin-3 (Gal-3) expression in a mouse model of cardiomyopathy attributable to cardiomyocyte-restricted transgenic activation of β2-adrenoceptors. However, pharmacological and genetic inhibition of Gal-3 did not confer benefit in this model, implying that Gal-3 may not be a critical disease mediator of cardiac remodeling in this model.

The Janus-like Face of IL-4Rα in Macrophages during Liver Fibrosis

The Janus-like Face of IL-4Rα in Macrophages during Liver Fibrosis

Insights from human genetic studies of lung and organ fibrosis.

Genetic investigations of fibrotic diseases, including those of late onset, often yield unanticipated insights into disease pathogenesis. This Review focuses on pathways underlying lung fibrosis that are generalizable to other organs. Herein, we discuss genetic variants subdivided into those that shorten telomeres, activate the DNA damage response, change resident protein expression or function, or affect organelle activity. Genetic studies provide a window into the downstream cascade of maladaptive responses and pathways that lead to tissue fibrosis. In addition, these studies reveal interactions between genetic variants, environmental factors, and age that influence the phenotypic spectrum of disease. The discovery of forces counterbalancing inherited risk alleles identifies potential therapeutic targets, thus providing hope for future prevention or reversal of fibrosis.

Advanced septa size quantitation determines the evaluation of histological fibrosis outcome in chronic hepatitis B patients

Hepatitis B (HBV)-related fibrosis can be reversed after effective antiviral therapy. However, detailed changes of collagen characteristics during fibrosis regression remain unclear. Paired biopsy samples obtained from chronic hepatitis B patients were imaged with second harmonic generation/two photon excitation fluorescence (SHG/TPEF)-based microscopy to identify and quantify collagen features in portal, septal, and fibrillar areas. According to the changes of Ishak stage and qFibrosis score, a total of 117 patients with paired liver biopsy appeared to have four different outcomes after 78-week antiviral therapy: fast reverse (9%), reverse (63%), stable (15%), or progress (13%) on fibrosis. Among 71 collagen features identified by SHG/TPEF analysis, the most prominent fibrosis reversion occurred in the “septal” area, followed by the “fibrillar” area, but not in the “portal” area (P < 0.001). Further analysis of 1060 individual septa identified four parameters that correlated with fibrosis reversion: average width, maximum width, number of fibers, and number of cross-link fibers (P < 0.001). Average septal width was independently associated with regressive septa (odds ratio (OR) = 5.22, 95% confidence interval (CI): 4.17–6.53; P < 0.001), with an AUROC of 0.96 (95% CI: 0.95–0.97). The threshold used to discriminate reversal of fibrosis was 30 μm. In conclusion, septal collagen was determined to be the most useful histological feature for evaluation of dynamic changes in liver fibrosis. Septal width was the most predictive indicator of prognosis in liver fibrosis.

Targeting renal fibrosis: Mechanisms and drug delivery systems.

Renal fibrosis is the common outcome of many chronic kidney diseases (CKD) independent of the underlying etiology. Despite a host of promising experimental data, currently available strategies only ameliorate or delay the progression of CKD but do not reverse fibrosis. One of the major impediments of translating novel antifibrotic strategies from bench to bedside is due to the intricacies of the drug delivery process. In this review, we briefly describe mechanisms of renal fibrosis and methods of drug transfer into the kidney. Various tools used in gene therapy to administer nucleic acids in vivo are discussed. Furthermore, we review the modes of action of protein- or peptide-based drugs with target-specific antibodies and cytokines incorporated in hydrogels. Additionally, we assess an intriguing new method to deliver drugs specifically to tubular epithelial cells via conjugation with ligands binding to the megalin receptor. Finally, plant-derived compounds with antifibrotic properties are also summarized.

In vivo hepatic differentiation potential of human umbilical cord-derived mesenchymal stem cells: Therapeutic effect on liver fibrosis/cirrhosis.

AIMTo investigate the hepatic differentiation potential of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) and to evaluate their therapeutic effect on liver fibrosis/cirrhosis.METHODSA CCl4-induced liver fibrotic/cirrhotic rat model was used to assess the effect of hUC-MSCs. Histopathology was assessed by hematoxylin and eosin (H&E), Masson trichrome and Sirius red staining. The liver biochemical profile was measured using a Beckman Coulter analyzer. Expression analysis was performed using immunofluorescent staining, immunohistochemistry, Western blot, and real-time PCR.RESULTSWe demonstrated that the infused hUC-MSCs could differentiate into hepatocytes in vivo. Functionally, the transplantation of hUC-MSCs to CCl4-treated rats improved liver transaminases and synthetic function, reduced liver histopathology and reversed hepatobiliary fibrosis. The reversal of hepatobiliary fibrosis was likely due to the reduced activation state of hepatic stellate cells, decreased collagen deposition, and enhanced extracellular matrix remodeling via the up-regulation of MMP-13 and down-regulation of TIMP-1.CONCLUSIONTransplanted hUC-MSCs could differentiate into functional hepatocytes that improved both the biochemical and histopathologic changes in a CCl4-induced rat liver fibrosis model. hUC-MSCs may offer therapeutic opportunities for treating hepatobiliary diseases, including cirrhosis.

Targeted apoptosis of myofibroblasts with the BH3 mimetic ABT-263 reverses established fibrosis.

Persistent myofibroblast activation distinguishes pathological fibrosis from physiological wound healing, suggesting that therapies selectively inducing myofibroblast apoptosis could prevent progression and potentially reverse established fibrosis in diseases such as scleroderma, a heterogeneous autoimmune disease characterized by multiorgan fibrosis. We demonstrate that fibroblast-to-myofibroblast differentiation driven by matrix stiffness increases the mitochondrial priming (proximity to the apoptotic threshold) of these activated cells. Mitochondria in activated myofibroblasts, but not quiescent fibroblasts, are primed by death signals such as the proapoptotic BH3-only protein BIM, which creates a requirement for tonic expression of the antiapoptotic protein BCL-XL to sequester BIM and ensure myofibroblast survival. Myofibroblasts become particularly susceptible to apoptosis induced by "BH3 mimetic" drugs inhibiting BCL-XL such as ABT-263. ABT-263 displaces BCL-XL binding to BIM, allowing BIM to activate apoptosis on stiffness-primed myofibroblasts. Therapeutic blockade of BCL-XL with ABT-263 (navitoclax) effectively treats established fibrosis in a mouse model of scleroderma dermal fibrosis by inducing myofibroblast apoptosis. Using a BH3 profiling assay to assess mitochondrial priming in dermal fibroblasts derived from patients with scleroderma, we demonstrate that the extent of apoptosis induced by BH3 mimetic drugs correlates with the extent of their mitochondrial priming, indicating that BH3 profiling could predict apoptotic responses of fibroblasts to BH3 mimetic drugs in patients with scleroderma. Together, our findings elucidate the potential efficacy of targeting myofibroblast antiapoptotic proteins with BH3 mimetic drugs in scleroderma and other fibrotic diseases.

Hepatic Fibrosis in Dogs.

Hepatic fibrosis is commonly diagnosed in dogs, often as a sequela to chronic hepatitis (CH). The development of fibrosis is a crucial event in the progression of hepatic disease that is of prognostic value. The pathophysiology of hepatic fibrosis in human patients and rodent models has been studied extensively. Although less is known about this process in dogs, evidence suggests that fibrogenic mechanisms are similar between species and that activation of hepatic stellate cells is a key step. Diagnosis and staging of hepatic fibrosis in dogs requires histopathological examination of a liver biopsy specimen. However, performing a liver biopsy is invasive and assessment of fibrotic stage is complicated by the absence of a universally accepted staging scheme in veterinary medicine. Serum biomarkers that can discriminate among different fibrosis stages are used in human patients, but such markers must be more completely evaluated in dogs before clinical use. When successful treatment of its underlying cause is feasible, reversal of hepatic fibrosis has been shown to be possible in rodent models and human patients. Reversal of fibrosis has not been well documented in dogs, but successful treatment of CH is possible. In human medicine, better understanding of the pathomechanisms of hepatic fibrosis is leading to the development of novel treatment strategies. In time, these may be applied to dogs. This article comparatively reviews the pathogenesis of hepatic fibrosis, its diagnosis, and its treatment in dogs.

Modified Xiaochaihu Decoction () Promotes Collagen Degradation and Inhibits Pancreatic Fibrosis in Chronic Pancreatitis Rats.

To investigate the effect of Modified Xiaochaihu Decoction (MXD, ) on collagen degradation in rats with chronic pancreatitis (CP). Rats were injected dibutyltin dichloride (DBTC, 7 mg/kg of body weight) into the right caudal vein to induce CP model. Thirty heallhy male Wistar rats were randomly divided into three groups by a random number table: the control, the model and the treatment groups. Rats of treatment group were administered MXD (10 g/kg of body weight) orally once daily starting from the day post-model establishment. Pancreatic tissues were harvested after 28-day feeding and fibrosis was evaluated by picro-sirius red staining. The contents of collagen type I and III were detected using enzymelinked immunosorbent assay (ELISA), the expression of matrix metalloproteinase 13 (MMP13) and tissue inhibitor of metalloproteinase 1 (TIMP1) was analyzed by Western blot and real-time polymerase chain reaction (PCR). The fibrosis scoring of pancreatic tissues, the concentrations of collagen type I and III, the expression levels of MMP13 and TIMP1 proteins and mRNA in the model group were all increased compared with the control group (P<0.05). After treatment with MXD, the fibrosis scoring of pancreatic tissues, the concentrations of collagen type I and III, the expression levels of MMP13 proteins and mRNA in the teatment group were all decreased compared with the model group (P<0.05), but there were no significant differences in the expression levels of TIMP1 proteins and mRNA (P>0.05). MXD could promote collagen degradation and reverse pancreatic fibrosis in CP rats via a mechanism involve up-regulation of MMP13 expression.

MiR-185 Inhibits Fibrogenic Activation of Hepatic Stellate Cells and Prevents Liver Fibrosis.

Recent studies have shown the effect of microRNAs on HSC activation and transformation, which is essential for the pathogenesis of liver fibrosis. In our study, we explored the role of miR-185 in liver fibrosis. Plasma miR-185 was detected in hepatitis B virus-related liver fibrosis patients (S2/3, n = 10) by Illumina HiSeq sequencing, and healthy volunteers were selected (n = 8) as the control group. We found that the plasma miR-185 level in fibrosis patients was significantly downregulated. CCl4-induced fibrosis tissues in mouse livers and TGF-β1-activated HSCs also presented downregulated miR-185 concomitant with an increased expression of RHEB and RICTOR. To explore the correlations, LX-2 cells were transiently transfected with miR-185 mimics. The expression levels of α-SMA, collagen I, and collagen III were decreased as well as RHEB and RICTOR. Inhibition of endogenous miR-185 increased fibrogenic activity. Furthermore, dual-luciferase reporter assays indicated that miR-185 inhibited the expression of RHEB and RICTOR by directly targeting their 3′ UTRs. Moreover, silencing RHEB and RICTOR suppressed α-SMA and collagen expression levels. In conclusion, miR-185 prevents liver fibrogenesis by inhibiting HSC activation via inhibition of RHEB and RICTOR. These results provide new insights into the mechanisms behind the anti-fibrotic effect of miR-185.

Anti-fibrotic activity of medicinal plants

&lt;p class="Abstract"&gt;The aim of this review is to report the medicinal plants which have anti- fibrotic effect characterized in different studies. They are summarized which include name of the plants, part used, liver fibrosis model, fraction of plant used and observations. The medicinal plants play an important role in treatment and prevention of liver fibrosis through different physiological mechanism. The effects of medicinal plant may delay the development of liver fibrosis and have potential to reverse or degrade the accumulation of extra cellular matrix. Four different databases are used and 18 plants are included which have the potential for reversal of liver fibrosis. There are also few more plants but they are not characterized well in literature.&lt;/p&gt;

Abstract 21353: Ccn5 Gene Therapy Suppresses Arrhythmias by Reversing Fibrosis in Mice With Chronic Angiotensin II Infusion

Background: Increased angiotensin II (ANG) levels elicit profibrotic effects which promote ventricular tachyarrhythmias (VT). Hypothesis: Gene delivery of the matricellular protein CCN5 ameliorates ANG related VT by reversing fibrosis. Methods: 8-10 wk old mice underwent ANG infusion (3mg/Kg/d) for 2wk after which they received 5E11 drp AAV9.CCN5 (ANGII+CCN5, n=8) or empty vector (ANGII, n=8) and were maintained for another 2wk. Optical mapping was performed in hearts that were challenged with right atrial (RA) burst trains (20Hz, 5-20 sec) to determine VT propensity. Fibrosis was assessed using trichrome staining. Results: VT was induced in 6/8 ANG, 2/8 ANG+CCN5, and 1/3 control hearts. A total of 34 trains elicited 13 VT episodes (38.4% rate) in ANG whereas 150 trains yielded only 6 episodes in ANG+CCN5 (4.0%). ANG increased the transepicardial APD gradient by causing selective APD prolongation on the RV side which was partially reversed by CCN5. No differences in the APD gradient were found between VT (+) and VT (-) hearts. Activation mapping revealed fixed lines of conduction block leading to onset of VT in ANG hearts. In contrast, RA trains caused shifting ventricular activation patterns that were normalized following the train in ANG+CCN5 (Fig). Extensive fibrotic lesions in ANG were reversed by CCN5 (Fig). Conclusions: Reversal of fibrosis by chronic CCN5 gene therapy suppresses the incidence of ANG related VT.