Generation of Urine-Derived Induced Pluripotent Stem Cells and Cerebral Organoids for Modeling Down Syndrome.

Down syndrome (DS, or trisomy 21, T21), is the most common genetic cause of intellectual disability. Alterations in the complex process of cerebral cortex development contribute to the neurological deficits in DS, although the underlying molecular and cellular mechanisms are not completely understood. Human cerebral organoids (COs) derived from three-dimensional (3D) cultures of induced pluripotent stem cells (iPSCs) provide a new avenue for gaining a better understanding of DS neuropathology. In this study, we aimed to generate iPSCs from individuals with DS (T21-iPSCs) and euploid controls using urine-derived cells, which can be easily and noninvasively obtained from most individuals, and examine their ability to differentiate into neurons and astrocytes grown in monolayer cultures, as well as into 3D COs. We employed nonintegrating episomal vectors to generate urine-derived iPSC lines, and a simple-to-use system to produce COs with forebrain identity. We observed that both T21 and control urine-derived iPSC lines successfully differentiate into neurons and astrocytes in monolayer, as well as into COs that recapitulate early features of human cortical development, including organization of neural progenitor zones, programmed differentiation of excitatory and inhibitory neurons, and upper-and deep-layer cortical neurons as well as astrocytes. Our findings demonstrate for the first time the suitability of using urine-derived iPSC lines to produce COs for modeling DS.

Interleukin-17a Induces Neuronal Differentiation of Induced-Pluripotent Stem Cell-Derived Neural Progenitors From Autistic and Control Subjects.

Prenatal exposure to maternal immune activation (MIA) has been suggested to increase the probability of autism spectrum disorder (ASD). Recent evidence from animal studies indicates a key role for interleukin-17a (IL-17a) in promoting MIA-induced behavioral and brain abnormalities reminiscent of ASD. However, it is still unclear how IL-17a acts on the human developing brain and the cell types directly affected by IL-17a signaling. In this study, we used iPSC-derived neural progenitor cells (NPCs) from individuals with ASD of known and unknown genetic cause as well as from neurotypical controls to examine the effects of exogenous IL-17a on NPC proliferation, migration and neuronal differentiation, and whether IL-17a and genetic risk factors for ASD interact exacerbating alterations in NPC function. We observed that ASD and control NPCs endogenously express IL-17a receptor (IL17RA), and that IL-17a/IL17RA activation modulates downstream ERK1/2 and mTORC1 signaling pathways. Exogenous IL-17a did not induce abnormal proliferation and migration of ASD and control NPCs but, on the other hand, it significantly increased the expression of synaptic (Synaptophysin-1, Synapsin-1) and neuronal polarity (MAP2) proteins in these cells. Also, as we observed that ASD and control NPCs exhibited similar responses to exogenous IL-17a, it is possible that a more inflammatory environment containing other immune molecules besides IL-17a may be needed to trigger gene-environment interactions during neurodevelopment. In conclusion, our results suggest that exogenous IL-17a positively regulates the neuronal differentiation of human NPCs, which may disturb normal neuronal and synaptic development and contribute to MIA-related changes in brain function and behavior.