IntroductionMesenchymal stromal cells (MSCs) are multipotent stem cells able to differentiate into mesoderm-derived cells, 1 and exhibit immunoregulatory properties. 2 MSCs have been used in the context of allogeneic hematopoietic stem cell transplantation to improve hematopoietic engraftment, to prevent graft failure, and to reduce the incidence or severity of acute graft-versus-host disease (GVHD). [3][4][5] MSCs obtained from bone marrow (BM) can undergo in vitro expansion in medium containing either fetal calf serum (FCS), with or without fibroblast growth factor (FGF-2), or platelet lysate (PL). 6 However, little is known about the effect of donor selection or culture conditions on the functional properties and therapeutic potential of clinical-grade MSCs.Recent studies have suggested that MSCs can contribute to tumor growth and metastasis. 7 A related concern is the capacity of MSCs for oncogenic transformation. Mouse MSCs show chromosomal abnormalities and are highly susceptible to transformation associated with an increased telomerase activity and myc expression, and a loss of p53 and p16. [8][9][10] In contrast, human MSCs are more resistant to transformation in vitro with no genomic instability detected and no tumor induced after long-term in vivo transfer. [11][12][13][14][15] After 20 to 50 population doublings (PDs), human MSCs undergo replicative senescence, with telomere shortening and increased p16 expression. 16 They require the same steps to achieve transformation as for differentiated cells, suggesting that they are not prone to spontaneous transformation. 17 Nevertheless, one recent study described the transformation of human adipose tissue-derived MSCs with up-regulation of myc, repression of p16, acquisition of telomerase activity, 18 and generation of carcinoma in mice. 19 We investigated the immune properties and resistance to transformation of MSCs produced in 4 cell therapy facilities during 2 multicenter clinical trials designed to evaluate the capacity of BM-MSCs to prevent acute GVHD or to treat irradiationinduced lesions. MethodsDetails regarding methods are provided in the supplemental data (available on the Blood website; see the Supplemental Materials link at the top of the online article). For personal use only. on March 28, 2019. by guest www.bloodjournal.org From (1A to 11A) were done for the GVHD prevention clinical trial, and 4 (12A, 13A2) to treat accidentally irradiated patients. For irradiated patients, 5 supplemental MSC productions (12B to 16B) were done using human PL. 6 MSC production Growth kinetics and MSC characterizationGrowth kinetics was assessed by studying total fold increase, total number of PDs, and colony-forming unit-fibroblast. MSCs were screened for the expression of CD45, CD73, CD105, CD90, and human leukocyte antigen-DR (HLA-DR) and were also checked for their capacity to stimulate the growth of allogeneic peripheral blood mononuclear cells (PBMCs) and to inhibit alloantigen-driven proliferation of PBMCs. Cytogenetic analysisAt the end of the first (P ...

High levels of TH and PHOX2B mRNA in PB at diagnosis objectively identify children with ultrahigh-risk disease who may benefit from novel treatment approaches. The level of TH, PHOX2B, and DCX mRNA in BM and/or PB at diagnosis might contribute to an algorithm to improve stratification of children for treatment.

The immunosurveillance mechanisms governing high-risk neuroblastoma (HR-NB), a major pediatric malignancy, have been elusive. We identify a potential role for natural killer (NK) cells, in particular the interaction between the NK receptor NKp30 and its ligand, B7-H6, in the metastatic progression and survival of HR-NB after myeloablative multimodal chemotherapy and stem cell transplantation. NB cells expressing the NKp30 ligand B7-H6 stimulated NK cells in an NKp30-dependent manner. Serum concentration of soluble B7-H6 correlated with the down-regulation of NKp30, bone marrow metastases, and chemoresistance, and soluble B7-H6 contained in the serum of HR-NB patients inhibited NK cell functions in vitro. The expression of distinct NKp30 isoforms affecting the polarization of NK cell functions correlated with 10-year event-free survival in three independent cohorts of HR-NB in remission from metastases after induction chemotherapy (n = 196, P < 0.001), adding prognostic value to known risk factors such as N-Myc amplification and age >18 months. We conclude that the interaction between NKp30 and B7-H6 may contribute to the fate of NB patients and that both the expression of NKp30 isoforms on circulating NK cells and the concentration of soluble B7-H6 in the serum may be clinically useful as biomarkers for risk stratification.

Interleukin-6 (IL-6) is known to promote tumour growth and survival. We evaluated IL-6 gene amplification in tumours from 53 glioma patients using fluorescence in situ hybridisation. Amplification events were detected only in glioblastomas (15 out of 36 cases), the most malignant tumours, and were significantly associated with decreased patient survival.