Extended Data Fig. 7: MISCOs allow the study of reciprocal connections from cortical and striatal tissue.
a, Day 60 VMWT-StrCAG-GFP-CtxWT MISCOs allow to study striatal innervation and show reciprocal GABA+ innervation from striatal into VM (a) and cortical (a’) tissue (white arrows), indicating reciprocal connectivity between VM and striatal tissue. Additionally, migrated interneurons into cortical tissues could be observed (yellow arrows). (representative images, similar results in n = 8/8 60-day-old MISCOs). b, Day 60 VMWT-StrWT-CtxCAG-GFP MISCOs display innervation from cortical tissue into both VM (b) as well as striatal tissue (b’), displaying cortical projection axon bundles (white arrows in b’) in the striatum as well as axonal innervation of mDA clusters in VM tissues (representative images, similar results in n = 6/6 60-day-old MISCOs). c, Striatal DARPP32+ clusters were readily innervated from cortical and VM tissues in day 40 VMCAG-tdTomato-StrWT-CtxCAG-GFP MISCOs (representative image, similar results in 6/6 organoids). d, Dopaminergic (TH+) neurons often cluster together and display heterogeneous morphologies (representative images, similar results in n = 13/13 organoids of 3 batches). e, Co-labeling of TH and GFP in VMWT -StrDLXi5/6-GFP-CtxWT MISCOs in striatal and cortical tissues allowed the observation of TH expressing interneurons (representative neurons of 2 recordings of 2 organoids). f–h, Putative dendritic spines (yellow arrows) and axonal boutons (white arrows) in Arch1-GFP transduced organoids in VM, striatal and cortical tissue. i, The injection site displayed HV (GFP+) and RV (Crimson+) double-transduced starter cells as well as monosynaptic, retrogradely transduced Crimson+ GFP− cells (representative image, similar results in n = 3/3 organoids of one batch). j, In the VM, neurons were RV positive, but helper virus negative, indicating retrograde spreading (representative image, similar results in n = 3/3 organoids of one batch). k, Number of starter cells of 500µm2 of whole organoid z projections of both injection site vs. VM. n = 3 MISCOs. Paired t-test, P = 0.0399. Data shown as mean ± SD.
