Biology subjects

Kan, S.-h.

Publications and source records attributed to Kan, S.-h..

3 recordsLinked to original sources

bioRxiv2022

Genetically corrected iPSC-derived Neural Stem Cell Grafts deliver NAGLU-IGFII fusion protein to affect CNS disease in Sanfilippo B Mice

Sanfilippo syndrome type B (Mucopolysaccharidosis type IIIB or MPS IIIB) is a recessive genetic disorder that severely affects the brain due to a deficiency in the enzyme -N-acetylglucosaminidase (NAGLU), leading to intralysosomal accumulation of partially degraded heparan sulfate. There are no effective treatments for this disorder. In this project, we carried out an ex vivo lentiviral correction of neural stem cells derived from Naglu-/- mice (iNSCs) using a modified enzyme in which the NAGLU is fused to an Insulin-like Growth Factor II receptor (IGFIIR) binding peptide in order to improve the cross-correction efficiency. After brain transplantation of these corrected iNSCs into Naglu-/- mice and long-term evaluation of the cross-correction, we successfully detected NAGLU-IGFII activity in all transplanted animals, as well as decreased lysosomal accumulation and reduced astrocytic and microglial activation throughout the transplanted brain. In addition, we identified a novel neuropathological phenotype in untreated brains characterized by decreased levels of MAP2 protein and accumulation of synaptophysin-positive aggregates in the brain. Following transplantation, this Naglu-/- -specific phenotype was altered with restored levels of MAP2 expression and significantly reduced formation of synaptophysin-positive aggregates. Our results demonstrate the feasibility and long-term benefit of genetically corrected iNSCs transplantation in the Sanfilippo B brain and effective cross-correction of Sanfilippo-associated pathology in Naglu-/- mice. Our findings suggest that genetically engineered iNSCs can be used to effectively deliver the missing enzyme to the brain and treat Sanfilippo type B-associated neuropathology.

neuroscience↗

bioRxiv2022

CRISPR-Mediated Generation and Characterization of a Gaa Homozygous c.1935C>A (p.D645E) Pompe Disease Knock-in Mouse Model Recapitulates Human Infantile Onset-Pompe Disease

Pompe disease (PD) is an autosomal recessive disorder caused by deficient lysosomal acid -glucosidase (GAA), leading to reduced degradation and subsequent accumulation of intra-lysosomal glycogen in tissues, especially skeletal and oftentimes cardiac muscle. The c.1935C>A (p.Asp645Glu) variant is the most frequent GAA pathogenic mutation in people of Taiwanese and Southern Chinese ethnicity, causing infantile-onset PD (IOPD), which presents neonatally with severe hypertrophic cardiomyopathy, profound muscle hypotonia, and respiratory failure leading to premature death if untreated. To further investigate the pathogenic mechanism and facilitate development of therapies pertaining to this variant, we applied CRISPR-Cas9 homology-directed repair (HDR) using a novel dual sgRNA approach flanking the target site to generate a GaaEm1935C>A knock-in mouse model as well as a myoblast cell line carrying the Gaa c.1935C>A mutation. Herein we describe the molecular, biochemical, physiological, histological, and behavioral characterization of 3-month-old homozygous GaaEm1935C>A mice. Homozygous GaaEm1935C>A knock-in mice exhibited normal Gaa mRNA expression levels relative to wild-type mice, but GAA enzymatic activity was almost completely abolished, leading to a substantial increase in tissue glycogen storage, and significant concomitant impairment of autophagy. Echocardiography of 3-month-old knock-in mice revealed significant cardiac hypertrophy. The mice also demonstrated skeletal muscle weakness but, paradoxically, not early mortality. Longitudinal studies of this model, including assessment of its immune response to exogenously supplied GAA enzyme, are currently underway. In summary, the GaaEm1935C>A knock-in mouse model recapitulates the molecular, biochemical, histopathologic, and phenotypic aspects of human IOPD caused by the GAA c.1935C>A pathogenic variant. It is an ideal model to assess innovative therapies to treat IOPD, including personalized therapeutic strategies that correct pathogenic variants, restore GAA activity and produce functional phenotypes.

genetics↗

bioRxiv2021

Recombinant NAGLU-IGF2 prevents physical and neurological disease and improves survival in Sanfilippo B syndrome

Recombinant human alpha-N-acetylglucosaminidase-insulin-like growth factor-2 (rhNAGLU-IGF2) is an investigational enzyme replacement therapy for Sanfilippo B, a lysosomal storage disease. Because recombinant human NAGLU (rhNAGLU) is poorly mannose 6-phosphorylated, we generated a fusion protein of NAGLU with IGF2 to permit its binding to the cation-independent mannose 6-phosphate receptor. We previously administered rhNAGLU-IGF2 intracerebroventricularly to Sanfilippo B mice, and demonstrated therapeutic restoration of NAGLU, normalization of lysosomal storage, and improvement in markers of neurodegeneration and inflammation. Here, we studied repeated intracerebroventricular rhNAGLU-IGF2 delivery in both murine and canine Sanfilippo B to determine potential effects on their behavioral phenotypes and survival. Treated mice showed improvement in disease markers such as heparan sulfate glycosaminoglycans, beta-hexosaminidase, microglial activation, and lysosomal-associated membrane protein-1. Sanfilippo B mice treated with rhNAGLU-IGF2 displayed partial normalization of their stretch attend postures, a defined fear pose in mice (p<0.001). We found an improved rotarod performance in Sanfilippo B mice treated with rhNAGLU-IGF2 compared to vehicle-treated Sanfilippo B mice (p=0.002). We also found a 61% increase in survival in Sanfilippo B mice treated with rhNAGLU-IGF2 (mean 53w, median 48w) compared to vehicle-treated Sanfilippo B mice (mean 33w, median 37w; p<0.001). In canine Sanfilippo B, we found that rhNAGLU-IGF2 administered into cerebrospinal fluid normalized HS and beta-hexosaminidase activity in gray and white matter brain regions. Proteomic analysis of cerebral cortex showed restoration of protein expression levels in pathways relevant to cognitive, synaptic, and lysosomal functions. These data suggest that treatment with rhNAGLU-IGF2 may improve the phenotype of Sanfilippo B disease.

neuroscience↗