Determining the Minimally Effective Dose of a Clinical Candidate AAV Vector in a Mouse Model of Crigler-Najjar...

Area of Science:

• * Gene Therapy
• * Metabolic Disorders
• * Molecular Biology

Background:

• * Crigler-Najjar syndrome is an inherited metabolic disorder caused by absent uridine diphosphate glucuronosyl transferase 1A1 (UGT1A1) activity.
• * This condition leads to dangerous levels of bilirubin in the blood, causing jaundice and hyperbilirubinemia.
• * Current phototherapy treatments for Crigler-Najjar syndrome lack long-term efficacy.

Purpose of the Study:

• * To evaluate the efficacy of a gene therapy approach using an adeno-associated virus (AAV) vector for treating Crigler-Najjar syndrome.
• * To determine the minimally effective dose of the AAV8.TBG.hUGT1A1co vector in a mouse model of the disease.

Main Methods:

• * Adult UGT1 knockout mice, rescued from phototherapy, were intravenously injected with varying doses of the AAV8.TBG.hUGT1A1co vector (2.5 × 10^10 to 2.5 × 10^13 genome copies/kg).
• * A control group received only the vehicle.
• * Clinical pathology, liver transaminases, and histopathological findings were monitored. Serum total bilirubin levels were assessed to determine treatment efficacy.

Main Results:

• * No significant vector-related adverse effects were observed, except for elevated liver transaminases in male mice at the highest dose.
• * Gene therapy with AAV8.TBG.hUGT1A1co reversed total bilirubin levels to wild-type levels at doses exceeding 2.5 × 10^11 genome copies/kg.
• * Histopathological examination revealed minimal to mild findings in both control and treated mice.

Conclusions:

• * Adeno-associated virus-mediated gene therapy is a safe and effective treatment for Crigler-Najjar syndrome in a mouse model.
• * The minimally effective dose for normalizing bilirubin levels was determined to be 2.5 × 10^11 genome copies/kg.
• * Gene therapy represents a viable therapeutic strategy for liver metabolism disorders like Crigler-Najjar syndrome.