OR12

A brain organoid model to study gene and cell therapy treatment for neuronopathic Gaucher disease

N Tanhuad(1) C Filardo(1) N Sutjarit(2) A Tubsuwan(3) T Pornsukjantra(2) S Hongeng(2) K Sii-Felice(1) E Payen(1)

1:UMR1184 CEA INSERM; 2:Faculty of Medicine Ramathibodi Hospital, Thailand; 3:Institute of Molecular Biosciences, Thailand

Gaucher disease (GD) is one of the most common lysosomal storage disorders caused by biallelic mutations in GBA1 gene, which alter the folding and function of the β-glucocerebrosidase (GCase) enzyme, leading to the accumulation of its glycolipid substrate within lysosomes. Enzyme replacement and substrate reduction therapies fail to control the neuropathology due to their inability to cross blood-brain barrier. Previous studies have shown that lysosomal enzymes can be secreted and taken up by surrounding cells (cross-correction process). Thus, overexpressing GCase in hematopoietic stem cells (HSC), which then colonize the CNS as microglia, may be more effective than transplanting unmodified allogenic cells. This can be achieved by genetically modifying HSCs to overexpress the enzyme. In this study, we successfully established an in vitro cerebral organoid model derived from induced pluripotent stem cells (iPSCs) of a healthy individual, a patient with the neurological form of GD (GBA1ᴸ⁴⁴⁴ᴾᐟᴸ⁴⁴⁴ᴾ), and mutated cells re-expressing wild-type GCase. These organoids contain neurons, astrocytes, and microglia, with similar cell numbers. However, significant structural abnormalities in mitochondria and rough endoplasmic reticulum (RER) were observed in the mutated organoid. Additionally, colocalization studies showed that GCase enzyme accumulates within RER in mutated condition. Remarkably, these abnormalities were corrected in the mutated cells re-expressing the wild-type form of the enzyme, suggesting that the neuronopathic form of GD caused by the homozygous L444P mutation could be corrected by providing the wild-type protein. This model provides a promising tool for selecting appropriate GCase vectors via microglial cells transduced by lentiviral vectors.