CD34 and graft versus host disease: MSCs indications were: GVHD in 18 patients (60%), 13 of them had aGVHD and 5 cGVHD; Grade 3–4 HC in 4 patients (13.3%), all cases being due to BK virus; PGF in 6 patients (20%), of whom 5 were co-infused with a CD34 + stem cell boost; primary GF in 2 (6.7%), to enhance engraftment after a subsequent HSCT.