RT Journal Article SR Electronic T1 Peripheral Nerve Single-Cell Analysis Identifies Mesenchymal Ligands that Promote Axonal Growth JF eneuro JO eNeuro FD Society for Neuroscience SP ENEURO.0066-20.2020 DO 10.1523/ENEURO.0066-20.2020 VO 7 IS 3 A1 Jeremy S. Toma A1 Konstantina Karamboulas A1 Matthew J. Carr A1 Adelaida Kolaj A1 Scott A. Yuzwa A1 Neemat Mahmud A1 Mekayla A. Storer A1 David R. Kaplan A1 Freda D. Miller YR 2020 UL http://www.eneuro.org/content/7/3/ENEURO.0066-20.2020.abstract AB Peripheral nerves provide a supportive growth environment for developing and regenerating axons and are essential for maintenance and repair of many non-neural tissues. This capacity has largely been ascribed to paracrine factors secreted by nerve-resident Schwann cells. Here, we used single-cell transcriptional profiling to identify ligands made by different injured rodent nerve cell types and have combined this with cell-surface mass spectrometry to computationally model potential paracrine interactions with peripheral neurons. These analyses show that peripheral nerves make many ligands predicted to act on peripheral and CNS neurons, including known and previously uncharacterized ligands. While Schwann cells are an important ligand source within injured nerves, more than half of the predicted ligands are made by nerve-resident mesenchymal cells, including the endoneurial cells most closely associated with peripheral axons. At least three of these mesenchymal ligands, ANGPT1, CCL11, and VEGFC, promote growth when locally applied on sympathetic axons. These data therefore identify an unexpected paracrine role for nerve mesenchymal cells and suggest that multiple cell types contribute to creating a highly pro-growth environment for peripheral axons.