Brain organoid modeling of Gaucher disease for identification of pathogenic pathways and therapy development

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Project Summary: The objective of this application is to establish a human brain organoid model of Gaucher disease (GD) for identification of pathological targets and testing of novel therapies. GD is an inherited lysosomal storage disease and included in newborn screening programs. Prevalence of GD is 1/50,000 live births in the general population. In GD, mutations in the coding region of the acid beta-glucosidase (GCase) gene, GBA1, result in progressive glycosphingolipid substrate accumulation and a continuum of clinical phenotypes in visceral organs and central nervous system (CNS). GD is classified as visceral (Type 1) or neuronopathic (Types 2 and 3) diseases. Typical manifestations of GD Type 1 include visceral, hematologic and bone diseases that are treated with enzyme replacement therapy or substrate reduction therapy. Type 2 is an acute, rapidly progressive neonatal CNS disease with no treatment available leading to death by 2 years. Type 3 is a subacute, progressive CNS and visceral disease presenting in childhood with potential survival into the 2nd to 5th decades with death caused by untreatable CNS disease. Neuronopathic GD (nGD) affects the CNS through progressive neurodegeneration and inflammation, leading to significant functional deficits and mortality. Newborn screening programs now facilitate diagnosis of presymtomatic newborns and treatment initiation before significant disease progression. However, no effective treatment for nGD exists. A major roadblock in identifying novel therapeutic options for nGD is the absence of a human experimental system faithfully recapitulating complex neural tissues. Traditional two-dimensional cell cultures and animal models have limitations in modeling complex brain tissues and faithfully mirroring human disease, respectively. In this application, we aim to establish a human brain organoid model of nGD for identification of pathological targets and future therapy development. We have successfully generated brain organoids from human nGD induced pluripotent stem cells (iPSCs) and created isogenic control iPSCs by genetic correction of the GBA1 mutation. Furthermore, we have confirmed the nGD phenotype and identified dysregulated pathways in nGD iPSCs and iPSC-derived neural precursor cells. These preliminary studies establish the feasibility of brain organoid modeling of nGD and support our hypothesis that nGD iPSC-derived brain organoids will exhibit GD-relevant phenotypes and provide a platform for studying GD pathogenesis and testing therapies. In this proposal, we will generate and characterize brain organoids derived from human nGD iPSCs, validate nGD phenotypes and identify dysregulated pathways (Aim 1). Furthermore, we will test a therapeutic approach of substrate reduction therapy in nGD brain organoids and determine anti-nGD effects and safety in a human disease-relevant brain model (Aim 2). The generation of 3D brain organoids provides a physiologically-relevant system for study of human brain biology and diseases and testing novel therapies. The outcome will facilitate clinical translation to prevent the high morbidity and mortality in nGD.