Individualized Use of 6-Mercaptopurine in Chinese Children with ALL: A Multicenter Randomized Controlled Trial.

Continuous 6-mercaptopurine (6-MP) dose titration is necessary because of its narrow therapeutic index and frequently encountered dose-limiting hematopoietic toxicity. However, evidence-based guidelines for gene-based 6-MP dosing have not been established for Chinese children with acute lymphoblastic leukemia (ALL). This multicenter, randomized, open-label, active-controlled clinical trial randomly assigned Chinese children with low- or intermediate-risk ALL in a 1:1 ratio to receive TPMT-NUDT15 gene-based dosing of 6-MP (N = 44, 10 to 50 mg/m2 /day) or standard dosing (N = 44, 50 mg/m2 /day) during maintenance therapy. The primary end point was the incidence of 6-MP myelosuppression in both groups. Secondary end points included frequencies of 6-MP hepatotoxicity, duration of myelosuppression and leukopenia, event-free survival, and steady-state concentrations of active metabolites (6-thioguaninenucleotides and 6-methylmercaptopurine nucleotides) in erythrocytes. A 2.2-fold decrease in myelosuppression, the primary end point, was observed in the gene-based-dose group using ~ 50% of the standard initial 6-MP dose (odds ratio, 0.26, 95% confidence interval, 0.11 to 0.64, P = 0.003). Patients in the gene-based-dose group had a significantly lower risk of developing thiopurine-induced myelosuppression and leukopenia (P = 0.015 and P = 0.022, respectively). No significant differences were observed in the secondary end points of the incidence of hepatotoxicity and steady-state concentrations of active metabolites in erythrocytes between the two groups. TPMT- and NUDT15-based dosing of 6-MP will significantly contribute toward further reducing the incidence of leukopenia in Chinese children with ALL. This trial is registered at www.clinicaltrial.gov as #NCT04228393.

[Influence of vascular endothelial growth factor on endothelial components in human bone marrow and umbilical cord mesenchymal stem cells].

This study was aimed to compare the proportion of endothelial cells (EC) in human bone marrow mesenchymal stem cell (BM-MSC) and human umbilical cord mesenchymal stem cells (UC-MSC), and to investigate the influence of vascular endothelial growth factor (VEGF) on proportion of EC in MSC. Flow cytometry was used to detect the proportion of CD34(+)CD133(+) and vWF(+)CD31(+) double positive cells in MSC. Wright's staining was employed to observe the influence of VEGF on morphology of MSC. The expressions of CD34, CD133, CD31, vWF were detected by immunofluorescence. qRT-PCR was performed to detect the influence of VEGF on EC marker genes' expression of MSC. The results showed that there were a small amount of EC and endothelial progenitor cells (EPC) in obtained BM-MSC and UC-MSC. After exposed to VEGF 10 ng/ml for 24 h, aspect ratio of MSC and the proportion of EC increased, while proportion of EPC decreased. Expression of EC related marker genes such as Tie-2 and ecNOS up-regulated, especially in UC-MSC. It is concluded that small amount of EC and EPC exists in cultured BM-MSC and UC-MSC, VEGF can enhance the proportion and function of EC in MSC.

[Changes of biological characteristics and gene expression profile of umbilical cord mesenchymal stem cells during senescence in culture].

This study was purposed to investigate the changes of biological properties and expression patterns of the aging related genes in umbilical cord mesenchymal stem cells (UC-MSC) during in vitro culture. UC-MSC at passage 3 were served as the control cells and those at passage 15 were considered as the aged cells. The biological features of those two kinds of cells including morphology, proliferation activity and phenotypic profile were observed, and the differences of gene expression were analysed by the whole human genome oligo microarray. Several differential genes were selected for further confirmation by quantitative reverse transcription-polymerase chain reaction. The results showed that UC-MSC at passage 15 were larger in size and their proliferation rate was slower compared with those of cells at passage 3, while the positivity of CD44 and CD105 remained unchanged. Compared with UC-MSC at passage 3, relatively aged cells expressed higher levels of genes that are associated with small subunit of ribosome. Further analysis with Gene Ontology functional categories showed that the up-regulated genes were concentrated in those related to steroid biosynthesis, galactose metabolism and the development of autoimmune diseases and degenerative diseases and the down-regulated genes in UC-MSC at passage 15 were concentrated in cytoskeleton molecules, DNA structure binding, mRNA binding and protein function. Functional analysis with Kyoto Encyclopedia of Genes and Genomes functional pathway revealed that the expression of some genes responsible for ribosome composition was elevated while those of associated with extracellular matrix, focal adhesion and cell cycle progression were down-regulated. It is concluded that UC-MSC become senescent due to the declines in metabolism and proliferation activities.