MRC1 and Alzheimer disease: Systemically infused MSC-Exos induced expansion of Arginase-1 and Mannose receptor C type 1 (MRC1)-expressing M2 microglia cells and reduced accumulation of the amyloid-β peptide (Aβ) in the brains of AβPP/PS1 transgenic mice, used as a murine model of AD [23].