Study of GCN repeats of PHOX2B gene among individuals from southwest China and diagnosis of two patients with Congenital central hypoventilation syndrome / 中华医学遗传学杂志

OBJECTIVE@#To study the trinucleotide repeats of GCN (GCA, GCT, GCC, GCG) encoding Alanine in exon 3 of the PHOX2B gene among healthy individuals from southwest China and two patients with Congenital central hypoventilation syndrome (CCHS).@*METHODS@#The number and sequence of the GCN repeats of the PHOX2B gene were analyzed by capillary electrophoresis, Sanger sequencing and cloning sequencing of 518 healthy individuals and two newborns with CCHS, respectively.@*RESULTS@#Among the 1036 alleles of the 518 healthy individuals, five alleles were identified, including (GCN)7, (GCN)13, (GCN)14, (GCN)15 and (GCN)20. The frequency of the (GCN)20 allele was the highest (94.79%). And five genotypes were identified, which included (GCN)7/(GCN)20, (GCN)13/(GCN)20, (GCN)14/(GCN)20, (GCN)15/(GCN)20, (GCN)20/(GCN)20. The homozygous genotypes were all (GCN)20/(GCN)20, and the carrier rate was 89.58%. Four GCN sequences of the (GCN)20 homozygous genotypes were identified among the 464 healthy individuals. The GCN repeat numbers in the exon 3 of the PHOX2B gene showed no significant difference between the expected and observed values, and had fulfilled the,Hardy-Weinberg equilibrium. The genotypes of the two CCHS patients were (GCN)20/(GCN)25 and (GCN)20/(GCN)30, respectively.@*CONCLUSION@#It is important to determine the GCN repeats and genotypic data of the exon 3 of the PHOX2B gene among the healthy individuals. The number of GCN repeats in 518 healthy individuals was all below 20. The selection of appropriate methods can accurately detect the polyalanine repeat mutations (PARMs) of the PHOX2B gene, which is conducive to the early diagnosis, intervention and treatment of CCHS.

The research of brain glioma therapy for nude mouse using transgenic human umbilical cord mesenchymal stem cells overexpressing TRAIL / 中国输血杂志

【Objective】 To explore the establishment methods of transgenic human umbilical cord mesenchymal stem cells (hUC-MSCs) overexpressing tumor necrosis factor(TNF)-related apoptosis-inducing ligand (TRAIL) based on the transposons, and attempt to apply it on the nude mice mode with glioma. 【Methods】 PiggyBac transposon system specially designed by us was used to prepare non-targeting and Her2-targeting hUC-MSCs that can stably express TRAIL through puromycin screening. The glioma cells expressing firefly luciferase (U87MG-LUC) were injected into the skull of the immunodeficient mice (BALB/c-nu/nu) with 1×106 cells per mouse. After 7 days of injection, the mice transplanted with U87MG were detected with a small animal living imager to determine the size and location of the tumors in skull. Then we injected the glioma-transplantation nude mouse with two kinds of transgenic hUC-MSCs expressing TRAIL (named as untarget-TRAIL and target-TRAIL, respectively), or the non-transgenic hUC-MSCs (all 1×106 cells per mouse) or PBS (named as WT-MSCs and PBS for negative control) respectively, and then monitored the changes of tumor signals by a small animal living imager every week for 3~4 weeks. 【Results】 After six passages to expand the cells, the both transgenic cell lines can stably express TRAIL gene. Their ratio of green fluorescent protein (GFP) positive cells can reach 93%-97%, and the positive ratio of their MSC-specific surface markers still maintained normal (CD34+, CD45+, and HLA-DR+ all <0.1%, CD90>99%, CD73>88%, and CD105 >60%). The median survival time (d) of U87MG-transplanted nude mice in the groups of untarget-TRAIL, target-TRAIL, WT-MSCs, and PBS was 41 vs 39 vs 24 vs 23(P<0.05). 【Conclusion】 The transgenic hUC-MSCs overexpressing TRAIL gene can significantly prolong the survival time of nude mice with brain glioma.

Overexpression of p21 Has Inhibitory Effect on Human Hematopoiesis by Blocking Generation of CD43＋ Cells via Cell-Cycle Regulation

Background and Objectives@#p21, an important member of the Cip/Kip family, is involved in inhibitory effects of RUNX1b overexpression during the early stage of human hematopoiesis. @*Methods@#and Results: We established a human embryonic stem cell (hESC) line with inducible expression of p21 (p21/hESCs). Overexpression of p21 did not influence either mesoderm induction or emergence of CD34＋ cells, but it significantly decreased the production of CD43＋ cells and changed the expression profile of hematopoiesis-related factors, leading to the negative effects of p21 on hematopoiesis. @*Conclusions@#In RUNX1b/hESC co-cultures when RUNX1b was induced from D0, perturbation of the cell cycle caused by upregulation of p21 probably prevented the appearance of CD43＋ cells, but not CD34＋ cells. The mechanisms via which CD34＋ cells are blocked by RUNX1b overexpression remain to be elucidated.