Preclinical efficacy and safety of adeno-associated virus 5 alpha-galactosidase: A gene therapy for Fabry disease.

We developed a novel adeno-associated virus 5 gene therapy (AAV5-GLA) expressing human alpha-galactosidase A (GLA) under the control of a novel, small and strong, liver-restricted promoter. We assessed the preclinical potential of AAV5-GLA for treating Fabry disease, an X-linked hereditary metabolic disorder resulting from mutations in the gene encoding GLA that lead to accumulation of the substrates globotriaosylceramide and globotriaosylsphingosine, causing heart, kidney, and central nervous system dysfunction. Effects of intravenously administered AAV5-GLA were evaluated in (1) GLA-knockout mice aged 7-8 weeks (early in disease) and 20 weeks (nociception phenotype manifestation) and (2) cynomolgus macaques during an 8-week period.

Intrastriatal Administration of AAV5-miHTT in Non-Human Primates and Rats Is Well Tolerated and Results in miHTT Transgene Expression in Key Areas of Huntington Disease Pathology.

Huntington disease (HD) is a fatal, neurodegenerative genetic disorder with aggregation of mutant Huntingtin protein (mutHTT) in the brain as a key pathological mechanism. There are currently no disease modifying therapies for HD; however, -lowering therapies hold promise. Recombinant adeno-associated virus serotype 5 expressing a microRNA that targets mRNA (AAV5-miHTT) is in development for the treatment of HD with promising results in rodent and minipig HD models.

A Novel Organoid Model of Damage and Repair Identifies HNF4α as a Critical Regulator of Intestinal Epithelial Regeneration.

Background & Aims: Recent evidence has suggested that the intact intestinal epithelial barrier protects our body from a range of immune-mediated diseases. The epithelial layer has an impressive ability to reconstitute and repair upon damage and this process of repair increasingly is seen as a therapeutic target. In vitro models to study this process in primary intestinal cells are lacking.

A protocol for lentiviral transduction and downstream analysis of intestinal organoids.

Intestinal crypt-villus structures termed organoids, can be kept in sustained culture three dimensionally when supplemented with the appropriate growth factors. Since organoids are highly similar to the original tissue in terms of homeostatic stem cell differentiation, cell polarity and presence of all terminally differentiated cell types known to the adult intestinal epithelium, they serve as an essential resource in experimental research on the epithelium. The possibility to express transgenes or interfering RNA using lentiviral or retroviral vectors in organoids has increased opportunities for functional analysis of the intestinal epithelium and intestinal stem cells, surpassing traditional mouse transgenics in speed and cost.

Adeno-associated viral vector serotype 5 poorly transduces liver in rat models.

Preclinical studies in mice and non-human primates showed that AAV serotype 5 provides efficient liver transduction and as such seems a promising vector for liver directed gene therapy. An advantage of AAV5 compared to serotype 8 already shown to provide efficient correction in a phase 1 trial in patients suffering from hemophilia B, is its lower seroprevalence in the general population. Our goal is liver directed gene therapy for Crigler-Najjar syndrome type I, inherited severe unconjugated hyperbilirubinemia caused by UGT1A1 deficiency.

Polyinosinic acid blocks adeno-associated virus macrophage endocytosis in vitro and enhances adeno-associated virus liver-directed gene therapy in vivo.

Adeno-associated virus serotype 8 (AAV8) has been demonstrated to be effective for liver-directed gene therapy in humans. Although hepatocytes are the main target cell for AAV8, there is a loss of the viral vector because of uptake by macrophages and Kupffer cells. Reducing this loss would increase the efficacy of viral gene therapy and allow a dose reduction.

Ezetimibe: A biomarker for efficacy of liver directed UGT1A1 gene therapy for inherited hyperbilirubinemia.

As recently demonstrated in patients with factor IX deficiency, adeno-associated virus (AAV)-mediated liver-directed therapy is a viable option for inherited metabolic liver disorders. Our aim is to treat Crigler-Najjar syndrome type I (CN I), an inherited severe unconjugated hyperbilirubinemia, as a rare recessive inherited disorder. Because the number of patients eligible for this approach is small, the efficacy can only be demonstrated by a beneficial effect on the pathophysiology in individual patients.

Overexpression of insulin like growth factor binding protein 5 reduces liver fibrosis in chronic cholangiopathy.

The ATP-binding cassette, sub-family B member 4 knock-out mouse (Abcb4(-/-)) is a relevant model for chronic cholangiopathy in man. Due to the lack of this P-glycoprotein in the canalicular membrane of hepatocytes, the secretion of phospholipids into bile is absent, resulting in increased bile toxicity. Expression of insulin like growth factor binding protein 5 (Igfbp5) increases in time in the livers of these mice.

Mycophenolate mofetil impairs transduction of single-stranded adeno-associated viral vectors.

Adeno-associated virus (AAV) liver-directed gene therapy seems a feasible treatment for Crigler-Najjar syndrome type I, an inherited liver disorder characterized by severe unconjugated hyperbilirubinemia. Transient immunosuppression coupled with vector administration seems needed to overcome host immune responses that prevent long-term expression in patients. The immunosuppressive mycophenolate mofetil (MMF), which inhibits de novo synthesis of purines, is a promising candidate.

Towards liver-directed gene therapy for Crigler-Najjar syndrome.

Crigler-Najjar (CN) syndrome is a recessive inherited disorder caused by deficiency of uridine diphospho-glucuronosyl transferase 1A1. This hepatic enzyme catalyzes the glucuronidation of bilirubin, an essential step in excretion into bile of this neurotoxic compound. As a result, CN patients suffer from severe unconjugated hyperbilirubinemia and are at risk of bilirubin encephalopathy.