NITRO is an ARPA-H research program focused on developing new approaches to osteoarthritis treatment. Its work spans three areas: injectable or non-invasive bone regeneration, injectable or non-invasive cartilage regeneration, and replacement joints made from human cells. The program’s goal is to help the body repair damaged joint tissue and explore regenerative options for joints beyond repair. ARPA-H selected five performer teams, led by Duke, Washington University in St. Louis, the University of Colorado Boulder, Columbia University, and Case Western Reserve University.