Human embryoid bodies model basal lamina assembly and muscular dystrophy

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, that 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 dystroglycanopathies, which are caused by dysfunction of the ECM receptor dystroglycan. However, opportunities to study the basal lamina in various human disease tissues are restricted due to its limited accessibility. Here, we report the generation of embryoid bodies from human induced pluripotent stem cells to model basal lamina formation. 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 ECM-secreting endoderm. In dystroglycanopathy patient embryoid bodies, electron and fluorescence microscopy revealed ultrastructural basal lamina defects and reduced ECM assembly. 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 muscular dystrophies. Finally, we applied this system to evaluate an experimental ribitol supplement therapy on genetically diverse dystroglycanopathy patient samples.