Study on Duchenne muscular dystrophy gene mutation and prenatal diagnosis / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the characteristics of DNA mutations underlying Duchenne muscular dystrophy and provide prenatal diagnosis.</p><p><b>METHODS</b>Multiplex ligation-dependent probe amplification (MLPA) and denaturing high performance liquid chromatography (DHPLC) were applied for analyzing DMD gene mutations in 388 unrelated Chinese patients and 53 fetuses.</p><p><b>RESULTS</b>Respectively, 230 and 43 subjects were found to harbor a deletion (59.28%) or duplication (11.08%). Two deletion hotspots were identified, which have located at exons 45-54 and exons 3-19. Duplications were mainly detected at exons 2-43. Point mutations were identified in 29.64% of patients. Fifty three fetuses were prenatal diagnosed, among which 18 were identified as patients.</p><p><b>CONCLUSION</b>Frequencies of DMD gene deletions and duplications in China are similar to global data. Prenatal diagnosis can help to reduce births of DMD patients.</p>

Genotypic and clinical features of spinal muscular atrophy type 3 / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the genotypic and clinical features and laboratory examinations of spinal muscular atrophy type 3 (SMA III).</p><p><b>METHODS</b>Results of genetic testing and laboratory exams of 18 SMA III patients were collected and analyzed.</p><p><b>RESULTS</b>The average age of onset of patients was 6.1 years, with the course of disease lasting from 13 months to 28 years. All patients became symptomatic with lower extremity muscle weakness. The symptoms gradually aggregated, with proximal lower limb muscle becoming atrophic and proximal upper limb muscle becoming weak. Genetic testing indicated that all subjects possessed homozygous deletions of SMN1 gene. Electromyography (EMG) of 15 subjects indicated neurogenic damage. Whilst younger patients had normal level of creatine kinase (CK), elder patients had higher level of CK, though no linear correlation was found.</p><p><b>CONCLUSION</b>Full understanding of Clinical, especially the growth features of SMA III, in combination with genetic testing, can facilitate diagnosis and early intervention of the disease.</p>

Correlation between genotypes and phenotypes in pseudohypertrophic muscular dystrophy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the correlation between genotypes and phenotypes in Chinese patients with pseudohypertrophic muscular dystrophy.</p><p><b>METHODS</b>Patients with Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) were diagnosed clinically. Multiplex ligation-dependent probe amplification (MLPA) were performed to detect potential DMD gene mutations. The results were analyzed statistically.</p><p><b>RESULTS</b>Among 280 patients, 238(85.0%) were diagnosed with DMD, 35(12.50%) were diagnosed with BMD and 7(2.5%) were diagnosed with intermediate muscular dystrophin (IMD). Among these, 252(92.31%) were in-frame mutations, and 21(7.69%) were out-of-frame mutations. Twelve patients with DMD have carried in-frame mutations, 9 with BMD have carried frame-shift mutations, and 7 IMD patients have carried frame-shift mutation.</p><p><b>CONCLUSION</b>Most of the genotypes and phenotypes of DMD have complied with the reading-frame hypothesis. Patients with BMD with frame-shift mutations may facilitate understanding of the pathogenesis of DMD, and provide a theoretical basis for clinical therapy.</p>

Population intervention of thalassemia relying on family planning service system / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To set up thalassemia population intervention model in order to decrease the birth of thalassemia major, relying on population and family planning service system.</p><p><b>METHODS</b>Pregnant women and their husbands were educated about thalassemia, and participated in screening and prenatal diagnosis if the couple were carriers of thalassemia in the areas of Huangpu, Panyu, Zengcheng and Tianhe districts of Guangzhou.</p><p><b>RESULTS</b>The network of thalassemia intervention mainly dependent on family planning service system was set up in these regions. A total of 10 695 families participated in thalassemia screening and 16 thalassemia major fetuses were diagnosed in the last two years. No one was thalassemia major in the 8360 newborn.</p><p><b>CONCLUSION</b>Thalassemia population intervention model was set up relying on family planning service system and it significantly decreased the birth of thalassemia major.</p>

Study of dystrophin gene non-deletion/duplication mutations causing Becker muscular dystrophy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify potential mutations in patients featuring Becker muscular dystrophy (BMD) and to enhance the understanding of non-deletion/duplication mutations of the dystrophin gene causing BMD.</p><p><b>METHODS</b>Clinical data of two patients affected with BMD were collected. Potential mutations in the dystrophin gene were screened with multiplex ligation-dependent probe amplification assay (MLPA). Biopsied muscle samples were examined with HE staining, immnostaining with anti-dystrophin antibody, and electronic microscopy.</p><p><b>RESULTS</b>MLPA assay suggested that both cases were probably due to non-deletion/duplication mutations of the dystrophin gene. Light and electronic microcopy of skeletal muscle biopsies confirmed dystrophic changes in both patients. For patient A, immunostaining showed non-contiguous weak staining for most parts of sarcolemma. For patient B, immunostaining showed positive result with N-terminal anti-dystrophin antibody and negative result with C-terminal anti-dystrophin antibody.</p><p><b>CONCLUSION</b>For patients with mild phenotypes but without dystrophin gene deletion/duplication, muscle biopsy and immunochemistry are helpful for diagnosis and prognosis.</p>

Expressions of myogenic markers in skeletal muscle differentiation of human bone marrow mesenchymal stem cells / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the expressions of myogenic markers MyoD, myogenin,and desmin in skeletal muscle differentiation of human bone marrow mesenchymal stem cells (hBM-MSCs).</p><p><b>METHODS</b>Myogenic markers MyoD, myogenin,and desmin of hBM-MSCs cultured in vitro were detected by immunofluorescence and RT-PCR. A total of 21 8-to-10 week-old immunosuppressed mdx mice were transplanted with 1x107 passage 5 of hBM-MSCs. The mice were euthanized 2-24 weeks after transplantation,and gastrocnemius muscle were analyzed for human MyoD, myogenin,desmin,and dystrophin (Dys) expressions by immunohistochemistry and RT-PCR.</p><p><b>RESULTS</b>The numbers of MyoD-,myogenin-,and desmin-positive cells per 100 hBM-MSCs were 23.5∓5.3, 30.7∓6.2, and 28.4∓5.7, respectively. MyoD, myogenin, and desmin mRNA was observed in passage 5 of hBM-MSCs. After two weeks of hBM-MSCs transplantation,a small number of MyoD-and myogenin-positive cells were observed in skeletal muscle of mdx mice,and desmin-positive cells were observed 4 weeks after transplantation. Expressions of MyoD and myogenin were detected in the muscle of mdx mice 2-4 weeks after hBM-MSCs transplantation, which reached a peak 12-16 weeks later. Desmin was expressed in the muscle of mdx mice 4-8 weeks after transplantation,with much more expression after 16 weeks of transplantation. A small number of Dys-positive cell and Dys mRNA expression were presented in the muscle of mdx mice 4 and 8 weeks after hBM-MSCs transplantation,respectively. The expression of Dys in the muscle of mdx mice increased gradually after transplantation.</p><p><b>CONCLUSION</b>hBM-MSCs have the potential of myogenic differentiation in vitro and contribute to myogenic conversion in xenogeneic animal,during which the up-regulation of MyoD and myogenin expressions may play an important role.</p>

Mesenchymal stem cells transplanted in mdx mice differentiate into myocytes and express dystrophin/utrophin / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the differentiation of rat bone marrow mesenchymal stem cells (MSCs) into myocytes and their expression of dystrophin/utrophin after transplantation in mdx mice.</p><p><b>METHODS</b>BrdU-labeled fifth-passage rat MSCs were transplanted in mdx mice with previous total body gamma irradiation (7 Gy). At 4, 8, 12 and 16 weeks after the transplantation, the mice were sacrificed to detect dystrophin/BrdU and utrophin expressions in the gastrocnemius muscle using immunofluorescence assay, RT-PCR and Western blotting. Five normal C57 BL/6 mice and 5 mdx mice served as the positive and negative controls, respectively.</p><p><b>RESULTS</b>Four weeks after MSC transplantation, less than 1% of the muscle fibers of the mdx mice expressed dystrophin, which increased to 15% at 16 weeks. Donor-derived nuclei were detected in both single and clusters of dystrophin-positive fibers. Some BrdU-positive nuclei were centrally located, and some peripherally within myofibers. Utrophin expression decreased over time after transplantation.</p><p><b>CONCLUSION</b>The myofibers of mdx mice with MSC transplantation express dystrophin, which is derived partially from the transplanted MSCs. Dystrophin expression from the transplanted MSCs partially inhibits the upregulation of utrophin in mdx mouse muscle, showing a complementary relation between them.</p>

Comparison of transduction efficiencies of various gene vectors in human bone-marrow-derived mesenchymal stem cells / 中国医学科学院学报

<p><b>OBJECTIVE</b>To compare the transduction efficiencies of adenoviral vector, adeno-associated viral vector, baculoviral vector, and plasmid vector in human bone-marrow-derived mesenchymal stem cells (hBMSCs).</p><p><b>METHODS</b>The hBMSCs were cultured in vitro and transducted with the adenoviral vector, adeno-associated viral vector, baculoviral vector, and plasmid vector. The expression of target protein was observed by inverted fluorescent microscopy and flow cytometry.</p><p><b>RESULTS</b>Inverted fluorescent microscopy showed that some of the hBMSCs after transduction expressed the green fluorescent protein (GFP) and the hBMSCs transducted with baculoviral vector expressed more GFP than those of other three vectors. Flow cytometry showed that the transduction efficiencies and mean fluorescence intensities of the adenoviral vector, adeno-associated viral vector, and plasmid vector were 42%, 37%, and 22% and 158, 115, and 77, respectively, which were significantly lower than those of baculoviral vector (70%, P < 0.01; 212, P < 0.05; respectively).</p><p><b>CONCLUSION</b>Compared with the adenoviral vector, adeno-associated viral vector, and plasmid vector, the baculoviral vector has higher transduction efficiency in hBMSCs and therefore may be a more suitable gene vector for research in human gene therapy.</p>

Transduction of various mammalian bone marrow-derived mesenchymal stem cells by baculovirus / 生理学报

The use of stem cells will lead to novel treatments for a wide range of diseases due to their properties of self-renewing, pluripotent, and undifferentiated state, and the stem cells are usually genetically modified for cell and gene therapy. If the baculovirus, as a new gene vector, can be effectively transduced into various mammalian bone marrow-derived mesenchymal stem cells (BMSCs) in vitro, it will be a better gene vector to genetically modify the stem cells. The aim of the present study is to investigate the transduction efficiency of recombinant baculovirus (BacV-CMV-EGFP), which expressed a reporter gene encoding enhanced green fluorescent protein (EGFP) under a cytomegalovirus immediate early (CMV-IE) promoter, into various mammalian BMSCs. The BMSCs of mouse, rat, porcine, rhesus, and human were cultured primarily in vitro. After more than three passages, the mammalian BMSCs were seeded into dishes and cultured in a humidified incubator at 37 °C with 5% CO(2). When the cells reached about 80% confluence, the complete medium was removed by aspiration. The cells were transduced with recombinant baculovirus at a multiplicity of infection (MOI) of 200 vector genomes/cell with 500 μL PBS at 25 °C for 4 h. At the end of baculovirus transduction, cells were washed and incubated with 2 mL complete medium, and baculovirus-transduced mammalian BMSCs were cultured in a humidified incubator for 2 d. Then, the inverted fluorescent microscope was used to observe GFP expressions in different mammalian BMSCs, and flow cytometry was used to detect the transduction efficiency of baculovirus in various mammalian BMSCs. After more than three passages, the BMSCs of mouse, rat, porcine, rhesus, and human showed a homogeneous spindle-shaped morphology. Compared with the BMSCs of mouse, rat and porcine, the inverted fluorescent microscope observations showed that there were more BMSCs expressing GFP and greater mean fluorescence intensity in rhesus and human transduced with baculovirus. The baculovirus could efficiently transduce into the BMSCs of mouse, rat, porcine, rhesus and human, and the transduction efficiency was (20.21±3.02)%, (22.51±4.48)%, (39.13±5.79)%, (71.16±5.36)% and (70.67±3.74)%, respectively. In conclusion, baculovirus displays different transduction efficiency into various mammalian BMSCs. Due to the high transduction efficiency for primate and human BMSCs, baculovirus is possibly a more suitable gene vector to genetically modify BMSCs of human and primates.

Dynamic distribution of implanted human bone marrow mesenchymal stem cells in mdx mice / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the dynamic distribution of human bone marrow mesenchymal stem cells (hBM-MSCs) in mdx mice.</p><p><b>METHODS</b>Twenty-four 8-10-week-old immunocompromised mdx mice were transplanted with 1 x 10(7) passage 5 hBM-MSCs labeled with bromodeoxyuridine (BrdU) by means of injection into the tail vein. The mice were euthanized 48 hours and 2, 4, 8, 12, 16, 20, and 24 weeks after transplantation. BrdU-positive cells in tissue and organs of the mice were detected by immunofluorescence analysis. Skeletal muscle was stained for anti-human nuclei mouse monoclonal antibody (anti-Hu) and analyzed for human dystrophin (Dys) expression by immunohistochemistry and reverse transcription-polymerase chain reaction.</p><p><b>RESULTS</b>After transplantation, BrdU-positive cells were found in most organs (especially in bone marrow, liver, and lung) within 4 weeks, and these cells in liver and lung decreased gradually after 4 weeks. At 48 hours after transplantation, BrdU-positive cells were found in bone marrow, which reached a peak level after 2 weeks and were still detectable after 16 weeks. BrdU-positive cells in skeletal muscle increased gradually over time of transplantation. A small number of anti-Hu positive cells were detected in skeletal muscle 2 weeks after transplantation. A small number of Dys positive cell were seldom found at 4 weeks and small Dys mRNA expression detected 4 weeks after transplantation. The proportion of anti-Hu in parallel with Dys positive cells and Dys mRNA in skeletal muscle of mdx mice increased gradually over time of transplantation.</p><p><b>CONCLUSION</b>After being transplanted into mdx mice, hBM-MSCs are mainly distributed in bone marrow, liver, and lung during the early time (2-4 weeks) , and then in bone marrow and skeletal muscle (after 4 weeks).</p>

Preliminary study of the spatial structural and functional changes of dystrophin after exon-3 deletion / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the structural and functional changes of dystrophin molecule after exon 3 deletion.</p><p><b>METHODS</b>Three-dimensional models of dystrophin comprising the major domains were established before and after exon 3 deletion using SWISS-MODEL server. The motifs and structural domains of dystrophin after exon 3 deletion were searched in Pfam database, and the crystal structure of the actin-binding domain in the dystrophin molecule was analyzed using Rasmol software.</p><p><b>RESULTS</b>Torsion of the N-terminal actin-binding domain occurred in the dystrophin molecule after deletion of exon 3. Homology analysis based on Pfam database searches indicated that following exon 3 deletion, the Bit score of the first calponin homology (CH1) domain was decreased from 108 to 36.5 while its expectation value increased from 2.3e-9 to 8.1e-8. The deletion also resulted in the absence of the spiral region C from the CH1 domain.</p><p><b>CONCLUSION</b>Exon 3 deletion in the dystrophin-coding sequence decreases the stability of CH1 domain and prevents the formation of the junction interface where dystrophin binds to actin. The bioinformatics approach provides a new alternative for investigation of the pathogenesis of DMD pathogenesy investigation.</p>

Dystrophin expression in mdx mice after bone marrow stem cells transplantation / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the dynamic changes of dystrophin expression in mdx mice after bone marrow stem cells transplantation.</p><p><b>METHODS</b>The bone marrow stem cells of C57 BL/6 mice (aged 6 to 8 weeks) were injected intravenously into the mdx mice (aged 7 to 9 weeks), which were preconditioned with 7Gy gamma ray. The amount of dystrophin;expression in gastrocnemius was detected by immunofluorescence, reverse transcription-polymerase chain reaction and Western blot at week 5, 8, 12 and 16 after transplantation.</p><p><b>RESULTS</b>At week 5 after bone marrow stem cells transplantation, the dystrophin expression detected in mdx mice were very low; however, its expression increased along with time. At week 16 week, about 12% muscle cells of all transplanted mice expressed dystrophin. There were less centrally placed myonuclei than the control mdx mice, whereas peripheral myonuclei increased.</p><p><b>CONCLUSIONS</b>After having been injected into mdx mice, the allogenic bone marrow stem cells have a trend to reach the injured muscle tissues and differentiate to fibers that can express dystrophin and the expression increased with time. The bone marrow stem cells participates in the repair and regeneration of the injured tissues permanently and constantly.</p>

Dystrophin expression and pathology of diaphragm muscles of mdx mice after xenogenic bone marrow stem cell transplantation / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of bone marrow stem cell transplantation (BMT) on the diaphragm muscles of mdx mice, a mouse model of Duchenne muscular dystrophy (DMD).</p><p><b>METHODS</b>The bone marrow-derived stem cells form male SD rats was transplanted through the tail vein into 18 female 8-week-old mdx mice, which were sacrificed at 4, 8 and 12 weeks after BMT (6 at each time point), respectively. The diaphragm muscles of the mice were subjected to HE staining, immunofluorescence detection of dystrophin, reverse transcription (RT)-PCR analysis of dystrophin mRNA transcripts and PCR analysis of Sry (sex-determining region on the Y chromosome) gene, with age-matched female C57 mice and untreated mdx mice as the controls.</p><p><b>RESULTS</b>The proportion of centrally nucleated fibers (CNF) in the diaphragm muscle of the recipient mdx mice was (15.58+/-0.91) %, (12.50+/-1.87) % and (10.17+/-1.17) % at 4, 8 and 12 weeks after BMT, respectively, significantly smaller than that of untreated mdx mice [(19.5+/-1.87) %], and the fibers after BMT showed less inflammatory infiltration. Compared with the untreated mice, the recipient mdx mice showed green fluorescence on significantly more diaphragm muscle cell membranes [with the proportion of dystrophin-positive fibers of (1.00+/-0.32) %, (6.00+/-1.05) % and (11.92+/-1.11) % at 4, 8, and 12 weeks after BMT]. RT-PCR of dystrophin mRNA also demonstrated significantly higher relative levels of dystrophin in the recipient mdx mice (0.19+/-0.05, 0.26+/-0.06 and 0.36+/-0.04 at 4, 8 and 12 weeks after BMT) than in untreated mdx mice, and Sry gene was present in the recipient mice.</p><p><b>CONCLUSION</b>BMT can partially restore dystrophin expression and ameliorate the pathology in the diaphragm muscles of mdx mice, and has great potential to produce general therapeutic effect in patients with DMD.</p>

Transfection and in vitro expression of human microdystrophin gene in rat mesenchymal stem cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct the eukaryotic expression vector of human microdystrophin gene and observe its expression in rat mesenchymal stem cells (rMSCs) in vitro.</p><p><b>METHODS</b>The plasmid PBSK-MICRO containing human microdystrophin cDNA was digested by restriction endonuclease, and the resultant microdystrophin fragment was inserted into the NotI site of pcDNA3.1(+) to prepare the eukaryotic expression vector-pcDNA3.1(+)/ microdystrophin, which was identified by endonuclease digestion and sequencing. The recombinant plasmid was transfected into rMSCs via lipofectamine, and after G418 selection, the expression of microdystrophin was detected by RT-PCR and indirect immunofluorescence assay.</p><p><b>RESULTS</b>Microdystrophin gene fragment was correctly inserted into the plasmid pcDNA3.1(+), as conformed by sequencing and digestion with Not I and Hind III. The total mRNA of the transfected rMSCs was extracted and microdystrophin mRNA expression was found in the cells by RT-PCR. Indirect immunofluorescence assay for the protein expression of microdystrophin showed bright red fluorescence in the transfected rMSCs.</p><p><b>CONCLUSION</b>Eukaryotic expression plasmid pcDNA3.1(+)/microdystrophin has been constructed successfully and microdystrophin can be expressed in transfected rMSCs in vitro, which may facilitate further research of Duchenne muscular dystrophy treatment by genetically modified allogeneic stem cell transplantation.</p>

Therapy of Duchenne muscular dystrophy with umbilical cord blood stem cell transplantation / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To analyze a Duchenne muscular dystrophy(DMD) patient's muscular regeneration, dystrophin expression and locomotive variation before and after he underwent umbilical cord blood stem cell transplantation in order to assess the therapeutic effect.</p><p><b>METHODS</b>A 12-year-old DMD boy who could not walk for 3 years was confirmed by gene analysis and dystrophin protein immune test on his muscle. He had no other chronic disease. By HLA matching, a piece of umbilical cord blood stem cell with 6 HLA sites matching to the boy was found in Guangdong Umbilical Cord Blood Bank. The number of the nucleated cells of the umbilical cord blood stem cell was 24.08x 10(8). After pretreatment for the DMD boy with busulfan, cyclophosphamide and rabbit anti-human thymocyte globulin, the allergenic cord blood stem cells were transplanted into him by intravenous injection. Cyclosporin A, methylprednisolone, MMF, prostaglandin E1 and ganciclovir were given after the transplantation. At the same time, Gran, the granulocytic cell stimulating factor, and gamma globulin were administered. The biochemistry profile including serum creatine kinase (CK), the reconstruction of blood making, the deletion exon of DMD gene, the regenerating muscles, the dystrophin protein expression, and the locomotive function of the DMD boy were tested regularly.</p><p><b>RESULTS</b>(1) The white blood cells (WBC) of peripheral blood decreased gradually to zero after pretreatment. In a period of 15 days after transplantation, the neutrophil increased to 0.5x 10(9)/L; at 25 days, WBC increased to normal level. Blood platelet was more than 20x 10(9)/L at 22 days. The hemoglobin rose to 85-100 g/L. At 140 days, sternal puncture revealed the rapid growth of neutrophil, blood platelet and hemoglobin. (2)At 140 days, the blood type of the DMD boy transformed from type O to type AB (the donor's blood type being AB). There was no grafe versus host reaction. (3) At 18, 30, 43, 55, 74 and 233 days after transplantation, the PCR-short tandem repeat test of the boy's peripheral blood DNA showed that his genotype was completely the same as the donor's. The results of PCR-short tandem repeat tests of the bone marrow cells DNA by sternal puncture at 140, 183 and 235 days were the same as those of the blood DNA. (4) At 60 days, DMD gene analysis by PCR showed that the defected DMD gene (exon 19 deletion) had been corrected by the umbilical cord stem cells transplantation. (5) At 75 days, the biopsy of calf muscle showed there were myoblast cells and muscular tubes growing. The dystrophin expressions were weak, but a few of them were strong. DNA analysis showed that the donor's gene DNA accounted for 1%-13%. At 126 days, obviously increased dystrophin positive muscular fibers of the boy were found. The donor's fibers rose to 2.5%-25%. (6) The serum CK of the boy declined from 5735 U/L to 274 U/L. (7) At 100 days, physical examination revealed improvement in his arms and legs.</p><p><b>CONCLUSION</b>The therapy of Duchenne muscular dystrophy with allogeneic umbilical cord blood hematopoietic stem cell transplantation may reset up the blood-making function, decrease the serum CK level, restore the dystrophin in muscles, and improve the locomotive function of the DMD boy. These data suggest that the allogeneic umbilical cord blood hematopoietic stem cell transplantation may benefit the DMD boys.</p>