While both trials address the effect of multiple intravenous doses of MSC in OI children with COL1A1/COL1A2 abnormality, the BOOST2B trial, in addition to four doses of intravenous MSC (3 × 106 cells/kg), examines intraosseous injection (0.4 × 106 cells/kg) in all four lower limb long bones. The gene discussed is COL1A1; the disease is osteogenesis imperfecta.