Introduction
Basic mitochondrial biology
Clinical features of MD
Standard treatment options for MD
Methods of gene therapy (GT)
Zinc fingers nucleases (ZFN) and transcription activator-like effector nucleases (TALEN)
CRISPR/Cas9
GT in the focus of MD
Delivery
Organ | Serotype | References |
---|---|---|
Brain | AAV2 | [66], [67], [68] |
AAV5 | [69] | |
AAV8 | [70] | |
AAV9 | [58], [71], [72] | |
AAVrh.10 | [58], [73], [74], [75], [76] | |
Retina | AAV5, AAV2-HBKO | [77] |
AAV2.NN, AAV2.GL | [78] | |
AAV9 | [79] | |
Skeletal muscles | AAV1 | [80] |
AAV8 | [70], [80] | |
AAV9 | [80] | |
AAVrh.74 | [81] | |
Heart | AAV1 | [80] |
AAV6 | [61] | |
AAV8 | [61] | |
AAV9 | ||
AAVrh.10 | [58] | |
AAVrh.74 | [81] | |
Liver | AAV2, AAV5, AAV7, AAV8 | [82] |
AAV3B | [83] | |
AAV9 | [58] | |
AAVrh.10 | [58] | |
Pancreas | AAV2 | [66] |
AAV7 | [84] | |
Kidney | AAV3B | [83] |
AAV2, AAV5, AAV7, AAV8 | [82] | |
AAVrh74 | [81] | |
Gastro-intestinal tract | AAV6, AAV8, AAV9 | [61] |
AAV2 | [66] | |
AAV5 | [82] |
Mitochondrial transfer of GT components
Proteins
RNA
DNA
GT of diseases caused by nDNA mutations
TYMP
Slc25a46
OPA1
NDUFS4
Fdxr
ETHE1
Delivered gene | Description of model | Vector and route of administration | Effect | Reference |
---|---|---|---|---|
Full cDNA of human wild-type TYMP | Mitochondrial neurogastrointestinal encephalopathy syndrome (MNGIE) murine model (Double Tymp/Upp1 knockout) Represents nDNA mutation | Single intravenous (IV) administration of haematopoietic donor-derived cells with TYMP coding sequence transduced by lentiviral vector | Restoration of thymidine phosphorylase (TP) activities in peripheral blood cells of treated mice Decrease of plasma thymidine and deoxyuridine concentrations to levels in the range of wild-type mice | [113] |
Full cDNA of human wild-type TYMP | Mitochondrial neurogastrointestinal encephalopathy syndrome (MNGIE) murine model (Double Tymp/Upp1 knockout) Represents nDNA mutation | Single IV injection (tail vein) of AAV2/8-TBG-hcTYMP | Dose-dependent restoration of TP activity in the liver and improvement of biochemical abnormalities in the liver and blood (34 weeks after treatment) | [114], |
Full cDNA of human wild-type TYMP | Mitochondrial neurogastrointestinal encephalopathy syndrome (MNGIE) murine model (Double Tymp/Upp1 knockout) Represents nDNA mutation | Single IV injection (tail vein) of AAV2/8-TBG-hcTYMP | Dose-dependent restoration of TP activity in the liver and improvement of biochemical abnormalities in the liver and blood (21 months after treatment) | [115] |
Full cDNA of human wild-type TYMP | MNGIE murine model (Double Tymp/Upp1 knockout + chronic oral administration of thymidine and deoxyuridine) | Single IV injection (tail vein) of liver-targeted AAV vectors (AAV-TBG, AAV-AAT, or AAV-HLP) | Restoration of TP activity in liver Amelioration of biochemical abnormalities Improvement of motor functions AAV-AAT and AAV-HLP treatment prevented ventricular enlargement Normalization of the mitochondrial dNTP balance | [116] |
cDNA of mouse wild-type Slc25a46 | Slc25a46 knockout mice | Single IV injection (facial vein of pups) of neurotrophic AAV–PHP.B vector | Prolongation of lifespan Increase of bodyweight Attenuation of central nervous system defects and ataxia Attenuation of optic atrophy Restoration of mitochondrial morphology and activity in various tissues | |
cDNA of human wild type OPA1 | Hemizygous OPA1 ± mice carrying human OPA1 transgene with c.2708_2711delTTAG mutation | Single IVT injection of AAV2 serotype 2 vector | Modest restoration of visual acuity Prevention of loss of retinal ganglion cells number | [121] |
cDNA of codon-optimized versions of human OPA1 isoform 1 and 7 | Wild type mice with rotenone-induced retinal degeneration | Single IVT injection of AAV2 serotype 2 vector | Improvement of spatial visual function | [123] |
cDNA of Opa1 long isoform with 11 residues (190–200) deleted in the S1 cleavage site (Opa1-ΔS1) | Rats with ischemia–reperfusion retinal injury | Single IVT injection of AAV | Normalization of the ischemia–reperfusion-induced downregulation of β-tubulin ΙΙΙ and Brn3a Inhibition of the retinal thickness and the cell loss in the ganglion cells layer Attenuation of elevation of receptor-interacting protein 3 and cleavage of caspase 3 | [124] |
cDNA of human OPA1 long isoform with deletion of the S1 cleavage site (OPA1-v1ΔS1) | Rats with focal cerebral ischemia–reperfusion injury | Single IVT injection of AAV | Decrease of neurological deficit and attenuation of infarct volume Restoration of mitochondrial cristae morphology and mitochondrial length Preservation of mitochondrial integrity | [125] |
Human cDNA of wild-type NDUFS4 | Constitutive Ndufs4 − / − mouse model developing a rapidly progressive encephalopathy, starting ~ 40 days after birth | IV or intracerebroventricular (ICV) or IV + ICV injections of AAV2/9 | Systemic AAV2/9-hNDUFS4 restores complex I assembly and activity in peripheral tissues but does not ameliorate the clinical phenotype ICV injections of AAV2/9-hNDUFS4 slightly ameliorate the clinical phenotype in newborn Ndufs4 − / − mice Double IV + ICV injections in newborns of AAV2/9-hNDUFS4 ameliorate the clinical phenotype and increases lifespan of Ndufs4 − / − mice | [127] |
Human cDNA of wild-type NDUFS4 | Constitutive Ndufs4 − / − mouse model developing a rapidly progressive encephalopathy, starting ~ 40 days after birth | Single IV (tail vein in adult mice, temporal vein in
newborns) of AAV-PHP.B | Prolongation of the lifespan, improvement of motor functions and complex I assembly in adult mice Absence of effect and typical disease progression in newborns | [128] |
Human cDNA of wild-type NDUFS4 | Constitutive Ndufs4 − / − mouse model developing a rapidly progressive encephalopathy, starting ~ 40 days after birth | Single IV injection (retroorbital sinus) | Increase of survival rate and body weight Improvement of motor functions Prevention of neuronal and glial pathology Improvement of retinal function | [129] |
cDNA of murine wild-type Fdxr | Fdxr R389Q/R389Q mice | IV injections of AAV-PHP.B vector (temporal facial vein of neonatal mice) | Alleviation of neuronal gliosis and neurodegeneration in the CNS Mitigation of the optic atrophy, reduction of the movement disorders and sensory neuropathy Improvement of mitochondrial function, decrease of iron overload | |
cDNA of human wild-type ETHE1 | Ethe1 -/- mice | Intra-cardiac injections of AAV2/8 | Increase of survival rates and body weight Attenuation of biochemical abnormalities | [133] |
cDNA of human TK2 | Tk2KI mice | Single IV injection of AAV9 or sequential IV injection of AAV9 and AAV2 | enhanced replacement therapy with pyrimidine deoxynucleosides delaying disease onset and extending lifespan in mice | [136] |
TK2
GT of diseases caused by mtDNA mutations
Allotopic expression of mitochondrial genes
Replacement of mitochondrial proteins by orthologs
Direct mitochondrial transfer of mitochondrial genes
Shift of heteroplasmy
Antireplicative machines
Nucleases
TALEN and ZFN
CRISPR/Cas
Other nucleases
Nuclease | Brief description | Target | Reference |
---|---|---|---|
mitoTev‐TALE | Monomeric nuclease derived from T4 phage (I‐TevI). Smaller than TALEN and hence more suitable for package its coding gene into viral vectors | Programmable | [184] |
PstI | Bacterial PstI endonuclease was recoded to optimize expression in mammalian cells and cloned downstream to MTS. Human mtDNA harbours two restriction sites for PstI (at positions 6914 and 9024) | Positions 6914 and 9024 of human mtDNA | [173] |
Smal | Smal gene from Serratia marcescens appended by MTS sequence cloned from pCoxIV of Saccharomyces cerevisiae | T8399G mutation in NARP | [197] |
Mito-ApaLI-HA | Synthetic ApaLI endonuclease from Acetobacter pasterianus added by MTS coding sequence. For immunological detection of ApaLI, a hemagglutinin epitope tag was added to its C terminus | Specific site in mtDNA of BALB mice | [198] |