Identification of SARS-CoV-2 inhibitors using lung and colonic organoids.

There is an urgent need to create novel models using human disease-relevant cells to study severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) biology and to facilitate drug screening. Here, as SARS-CoV-2 primarily infects the respiratory tract, we developed a lung organoid model using human pluripotent stem cells (hPSC-LOs). The hPSC-LOs (particularly alveolar type-II-like cells) are permissive to SARS-CoV-2 infection, and showed robust induction of chemokines following SARS-CoV-2 infection, similar to what is seen in patients with COVID-19. Nearly 25% of these patients also have gastrointestinal manifestations, which are associated with worse COVID-19 outcomes1. We therefore also generated complementary hPSC-derived colonic organoids (hPSC-COs) to explore the response of colonic cells to SARS-CoV-2 infection. We found that multiple colonic cell types, especially enterocytes, express ACE2 and are permissive to SARS-CoV-2 infection. Using hPSC-LOs, we performed a high-throughput screen of drugs approved by the FDA (US Food and Drug Administration) and identified entry inhibitors of SARS-CoV-2, including imatinib, mycophenolic acid and quinacrine dihydrochloride. Treatment at physiologically relevant levels of these drugs significantly inhibited SARS-CoV-2 infection of both hPSC-LOs and hPSC-COs. Together, these data demonstrate that hPSC-LOs and hPSC-COs infected by SARS-CoV-2 can serve as disease models to study SARS-CoV-2 infection and provide a valuable resource for drug screening to identify candidate COVID-19 therapeutics.

Injured adult retinal axons with Pten and Socs3 co-deletion reform active synapses with suprachiasmatic neurons.

Despite advances in promoting axonal regeneration after adult central nervous system injury, elicitation of a large number of lesion-passing axons reform active synaptic connections with natural target neurons remains limited. By deleting both Pten and Socs3 in retinal ganglion cells, we report that optic nerve axons after prechiasm lesion robustly reinnervate the hypothalamus, form new synapses with neurons in the suprachiasmatic nucleus (SCN), and re-integrate with the existing circuitry. Photic or electric stimulation of the retinal axons induces neuronal response in SCN. However both the innervation pattern and evoked responses are not completely restored by the regenerating axons, suggesting that combining with other strategies is necessary to overcome the defective rewiring. Our results support that boosting the intrinsic growth capacity in injured neurons promotes axonal reinnervation and rewiring.