CHAT and paraplegia: To elucidate the specific contribution of these two cell types of the neurovascular unit to SC injury and paraplegia after ACC, and to determine how the functions of these cells is affected by the activity of miR-155, we developed two KO strains that specifically lack miR-155 expression either in ChAT+ neurons (MN-miR-155-KO), or in ECs (EC-miR-155-KO), as well as two KI strains that overexpress miR-155 specifically in ChAT+ neurons (MN-miR-155-KI) or ECs (EC-miR-155-KI).