Human embryoid bodies as a 3D tissue model of the extracellular matrix and α-dystroglycanopathies

Abstract

The basal lamina is a specialized sheet of dense extracellular matrix (ECM) linked to the plasma membrane of specific cell types in their tissue context, which serves as a structural scaffold for organ genesis and maintenance. Disruption of the basal lamina and its functions is central to many disease processes, including cancer metastasis, kidney disease, eye disease, muscular dystrophies and specific types of brain malformation. The latter three pathologies occur in the α-dystroglycanopathies, which are caused by dysfunction of the ECM receptor α-dystroglycan. However, opportunities to study the basal lamina in various human disease tissues are restricted owing to its limited accessibility. Here, we report the generation of embryoid bodies from human induced pluripotent stem cells that model the basal lamina. Embryoid bodies cultured via this protocol mimic pre-gastrulation embryonic development, consisting of an epithelial core surrounded by a basal lamina and a peripheral layer of ECMsecreting endoderm. In α-dystroglycanopathy patient embryoid bodies, electron and fluorescence microscopy reveal ultrastructural basal lamina defects and reduced ECM accumulation. By starting from patient-derived cells, these results establish a method for the in vitro synthesis of patient-specific basal lamina and recapitulate disease-relevant ECM defects seen in the α-dystroglycanopathies. Finally, we apply this system to evaluate an experimental ribitol supplement therapy on genetically diverse α-dystroglycanopathy patient samples. This article has an associated First Person interview with the first author of the paper.

Defective autophagy and increased apoptosis contribute toward the pathogenesis of FKRP-associated muscular dystrophies

“…Characterization of these three LGMDR9 iPS cell lines confirmed pluripotency ( Figures S2 A–S2C), normal karyotype (data not shown), and the presence of a single point mutation in c.826C > A, as shown by PCR and Sanger sequencing ( Figure S2 D). In addition to these novel lines, we also used the recently published iPS cell lines LGMDR9 CDI73, LGMDR9 compound heterozygous FP3 ( Dhoke et al., 2021 ) and B12-57 ( Nickolls et al., 2020 ), and WWS FP4 ( Ortiz-Cordero et al., 2021b ).…”

A universal gene correction approach for FKRP-associated dystroglycanopathies to enable autologous cell therapy

“…Given the recent identification of FKRP as a ribitol-5-phosphate transferase ( Kanagawa et al, 2016 ; Kuwabara et al, 2020 ), the therapeutic effect of ribitol supplementation is under investigation. Recent studies in FKRP mutant mice ( Cataldi et al, 2018 ) and patient-specific iPS cell derivatives ( Nickolls et al, 2020 ; Ortiz-Cordero et al, 2021b ) show the partial restoration of α-DG functional glycosylation upon treatment. An open-label study was announced in March 2021 to determine the safety and tolerability of ascending dose levels of BBP-418 (ribitol) for the treatment of ambulatory and non-ambulatory LGMDR9 patients ( NCT04800874 ).…”

Dystroglycanopathy: From Elucidation of Molecular and Pathological Mechanisms to Development of Treatment Methods

“…It is interpreted that the administration of ribitol increases CDP-Rbo production and enhances the enzymatic activity of mutant FKRP thereby improving DG glycosylation. Also, a report suggested that ribitol therapy is effective against the FKRP-L276I mutation, which is most commonly found in patients in Europe and the United States [ 89 ]. Ribitol therapy for FKRP mutation may also require residual FKRP enzymatic activity [ 90 ].…”