Targeted elimination of mutant mitochondrial DNA in MELAS-iPSCs by mitoTALENs

Mitochondrial diseases are maternally inherited heterogeneous disorders that are primarily caused by mitochondrial DNA (mtDNA) mutations. Depending on the ratio of mutant to wild-type mtDNA, known as heteroplasmy, mitochondrial defects can result in a wide spectrum of clinical manifestations. Mitochondria-targeted endonucleases provide an alternative avenue for treating mitochondrial disorders via targeted destruction of the mutant mtDNA and induction of heteroplasmic shifting. Here, we generated mitochondrial disease patient-specific induced pluripotent stem cells (MiPSCs) that harbored a high proportion of m.3243A>G mtDNA mutations and caused mitochondrial encephalomyopathy and stroke-like episodes (MELAS). We engineered mitochondrial-targeted transcription activator-like effector nucleases (mitoTALENs) and successfully eliminated the m.3243A>G mutation in MiPSCs. Off-target mutagenesis was not detected in the targeted MiPSC clones. Utilizing a dual fluorescence iPSC reporter cell line expressing a 3243G mutant mtDNA sequence in the nuclear genome, mitoTALENs displayed a significantly limited ability to target the nuclear genome compared with nuclear-localized TALENs. Moreover, genetically rescued MiPSCs displayed normal mitochondrial respiration and energy production. Moreover, neuronal progenitor cells differentiated from the rescued MiPSCs also demonstrated normal metabolic profiles. Furthermore, we successfully achieved reduction in the human m.3243A>G mtDNA mutation in porcine oocytes via injection of mitoTALEN mRNA. Our study shows the great potential for using mitoTALENs for specific targeting of mutant mtDNA both in iPSCs and mammalian oocytes, which not only provides a new avenue for studying mitochondrial biology and disease but also suggests a potential therapeutic approach for the treatment of mitochondrial disease, as well as the prevention of germline transmission of mutant mtDNA.

Generation of pluripotent stem cells using non-integrated approach in human azoospermia patients / 天津医药

Objective To establish induced pluripotent stem cells (iPSCs) in patients with azoospermia by non-integrated approach. Methods Using the commercially available serum-free medium (TeSR?2) and embryonic stem cell culture medium (Stem Adhere? Defined Matrix) to define the culture system, the iPSCs were established by using non-integrated Sendai virus infection in peripheral blood mononuclear cells of azoospermia patients. The immunofluorescence, karyotype analysis, embryoid body differentiation and teratoma formation were used to identify pluripotency, karyotype and differentiation ability of iPSCs. Results The established iPSCs showed the characteristics of human embryonic stem cells. Immunofluorescence analysis showed that octamer-binding transcription factor 4 (OCT4), SRY-related-box protein-2 (SOX2), stage-specific embryonic antigen-4 (SSEA-4) and tumor rejection antigen-1-60 (TRA-1-60) were positive for the expression of stem cell pluripotency markers. Karyotype analysis showed that they had normal karyotype. In addition, embryoid body and teratoma tests showed that the iPSCs had the ability to differentiate into three germ layers in vitro and in vivo. Conclusion The induction of pluripotent stem cell line is successfully constructed by non-integrated approach in azoospermia patients.

Construction of vascular endothelial growth factor modified muscle-derived stem cells and its expression / 实用医学杂志

Objective To construct the lentiviral vector encoding vascular endothelial growth factor gene and detect the vascular endothelial growth factor (VEGF) expression in muscle-derived stem cells (MDSCs). Methods To culture MDSCs and detect the CD34,CD45,Bcl-2 and Desmin expression in MDSCs by immunofluorescence. A cDNA encoding VEGF gene was amplified by PCR. This fragment was cut with EcoRI and BamHI and ligated with an EcoRI- and BamHI-reated lentiviral vector pCDH-CMV-MCS-EF1-copGFP. Then DNA sequencing analysis was performed to confirm successful construction of pCDH-CMV-MCS-EF1-copGFP -VEGF. The expression of VEGF was confirmed using enzyme-linked immunosorbent assay (ELISA), Western blot, and Real-time PCR analyses. Results The pCDH-CMV-MCS-EF1-copGFP-VEGF lentiviral vector was constructed successfully. When MOI values in the transfection efficiency MDSCs by FCM. were 1,5,15, the transfection rate reached to 16.7%, 45.6%, 66.3% and 85.6% respectively. When MOI value was of 20, the rate was up to 90.1%. Real-time PCR, Western blot and ELISA showed stable expression of VEGF in MDSCs. Conclusion We successfully constructed lentiviral vector carrying the VEGF and stable expression in MDSCs.