MSCs play an important role in the normal haematopoietic and leukaemic bone marrow niche.47, 48, 49 In particular, in vivo studies have shown that following cytotoxic treatment MSC cooperate with B-ALL cells to create a supportive microenvironment that confers chemoprotection.48 Consistent with these in vivo and previous in vitro studies,11, 12, 32, 50 we confirm that freshly sourced low-passage Nestin-positive MSCs are able to provide superior support for long-term in vitro expansion of primary and patient-derived lymphoid blasts compared with murine M210B4 or human TERT-immortalised MSCs. This evidence concerns the gene TERT and acute lymphoblastic leukemia.