Mitochondrial diseases include a group of maternally inherited genetic disorders caused by mutations in mtDNA. In most of these patients, mutated mtDNA coexists with wild-type mtDNA, a situation ...known as mtDNA heteroplasmy. Here, we report on a strategy toward preventing germline transmission of mitochondrial diseases by inducing mtDNA heteroplasmy shift through the selective elimination of mutated mtDNA. As a proof of concept, we took advantage of NZB/BALB heteroplasmic mice, which contain two mtDNA haplotypes, BALB and NZB, and selectively prevented their germline transmission using either mitochondria-targeted restriction endonucleases or TALENs. In addition, we successfully reduced human mutated mtDNA levels responsible for Leber's hereditary optic neuropathy (LHOND), and neurogenic muscle weakness, ataxia, and retinitis pigmentosa (NARP), in mammalian oocytes using mitochondria-targeted TALEN (mito-TALENs). Our approaches represent a potential therapeutic avenue for preventing the transgenerational transmission of human mitochondrial diseases caused by mutations in mtDNA. PAPERCLIP.
Background Atypical hemolytic uremic syndrome (aHUS) is a rare genetic life-threatening disease of chronic uncontrolled complement activation leading to thrombotic microangiopathy (TMA) and severe ...end-organ damage. Eculizumab, a terminal complement inhibitor approved for aHUS treatment, was reported to improve hematologic and renal parameters in 2 prior prospective phase 2 studies. This is the largest prospective study of eculizumab in aHUS to date, conducted in an adult population. Study Design Open-label single-arm phase 2 trial. Setting & Participants Patients 18 years or older with aHUS (platelet count <150 × 103 /μL, hemoglobin ≤ lower limit of normal, lactate dehydrogenase ≥1.5 × upper limit of normal ULN, and serum creatinine ≥ ULN) were included in this multicenter multinational study. Intervention Intravenous eculizumab (900 mg/wk for 4 weeks, 1,200 mg at week 5 and then every 2 weeks) for 26 weeks. Outcomes & Measurements Primary end point was complete TMA response within 26 weeks, defined as hematologic normalization (platelet count ≥150 × 103 /μL, LDH ≤ ULN), and preservation of kidney function (<25% serum creatinine increase from baseline), confirmed by 2 or more consecutive measurements obtained 4 or more weeks apart. Results 41 patients were treated; 38 (93%) completed 26 weeks of treatment. 30 (73%) were included during their first TMA manifestation. 30 (73%) had complete TMA response. Platelet counts and estimated glomerular filtration rates increased from baseline ( P < 0.001). All 35 patients on baseline plasma exchange/plasma infusion discontinued by week 26. Of 24 patients requiring baseline dialysis, 5 recovered kidney function before eculizumab initiation and 15 of the remaining 19 (79%) discontinued dialysis during eculizumab treatment. No patients lost existing transplants. Quality-of-life measures were significantly improved. Two patients developed meningococcal infections; both recovered, and 1 remained on eculizumab treatment. Limitations Single-arm open-label design. Conclusions Results highlight the benefits of eculizumab in adult patients with aHUS: improvement in hematologic, renal, and quality-of-life parameters; dialysis discontinuation; and transplant protection.
Retrospective studies suggest that online hemodiafiltration (OL-HDF) may reduce the risk of mortality compared with standard hemodialysis in patients with ESRD. We conducted a multicenter, ...open-label, randomized controlled trial in which we assigned 906 chronic hemodialysis patients either to continue hemodialysis (n=450) or to switch to high-efficiency postdilution OL-HDF (n=456). The primary outcome was all-cause mortality, and secondary outcomes included cardiovascular mortality, all-cause hospitalization, treatment tolerability, and laboratory data. Compared with patients who continued on hemodialysis, those assigned to OL-HDF had a 30% lower risk of all-cause mortality (hazard ratio HR, 0.70; 95% confidence interval 95% CI, 0.53-0.92; P=0.01), a 33% lower risk of cardiovascular mortality (HR, 0.67; 95% CI, 0.44-1.02; P=0.06), and a 55% lower risk of infection-related mortality (HR, 0.45; 95% CI, 0.21-0.96; P=0.03). The estimated number needed to treat suggested that switching eight patients from hemodialysis to OL-HDF may prevent one annual death. The incidence rates of dialysis sessions complicated by hypotension and of all-cause hospitalization were lower in patients assigned to OL-HDF. In conclusion, high-efficiency postdilution OL-HDF reduces all-cause mortality compared with conventional hemodialysis.
Transit-amplifying nephron progenitor cells (NPCs) generate all of the nephrons of the mammalian kidney during development. Their limited numbers, poor in vitro expansion, and difficult accessibility ...in humans have slowed basic and translational research into renal development and diseases. Here, we show that with appropriate 3D culture conditions, it is possible to support long-term expansion of primary mouse and human fetal NPCs as well as NPCs derived from human induced pluripotent stem cells (iPSCs). Expanded NPCs maintain genomic stability, molecular homogeneity, and nephrogenic potential in vitro, ex vivo, and in vivo. Cultured NPCs are amenable to gene targeting and can form nephron organoids that engraft in vivo, functionally couple to the host’s circulatory system, and produce urine-like metabolites via filtration. Together, these findings provide a technological platform for studying human nephrogenesis, modeling and diagnosing renal diseases, and drug discovery.
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•Derivation and long-term culture of mouse and human NPC lines•Rapid and efficient nephron organoid formation from mouse and human NPC lines•Long-term cultured NPC lines show nephrogenic potential in vivo•NPC lines enable gene editing and disease modeling
Li et al. report the derivation and long-term culture of mouse and human nephron progenitor cell lines under chemically defined conditions in 3D format. Expanded NPCs have nephrogenic potential in vitro and in vivo and allow the study of kidney organogenesis, gene editing, drug screening, and disease modeling.
Current genome-editing systems generally rely on inducing DNA double-strand breaks (DSBs). This may limit their utility in clinical therapies, as unwanted mutations caused by DSBs can have ...deleterious effects. CRISPR/Cas9 system has recently been repurposed to enable target gene activation, allowing regulation of endogenous gene expression without creating DSBs. However, in vivo implementation of this gain-of-function system has proven difficult. Here, we report a robust system for in vivo activation of endogenous target genes through trans-epigenetic remodeling. The system relies on recruitment of Cas9 and transcriptional activation complexes to target loci by modified single guide RNAs. As proof-of-concept, we used this technology to treat mouse models of diabetes, muscular dystrophy, and acute kidney disease. Results demonstrate that CRISPR/Cas9-mediated target gene activation can be achieved in vivo, leading to measurable phenotypes and amelioration of disease symptoms. This establishes new avenues for developing targeted epigenetic therapies against human diseases.
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•A CRISPR/Cas9 system transcriptionally activates endogenous target genes in vivo•Recruiting the transcriptional machinery induces trans-epigenetic remodeling•Inducing target gene expression leads to physiological phenotypes in postnatal mammals•The system ameliorates symptoms associated with several mouse models of human diseases
In vivo delivery of a Cas9-based epigenetic gene activation system ameliorates disease phenotypes in mouse models of type I diabetes, acute kidney injury, and muscular dystrophy
Aging is the major risk factor for many human diseases. In vitro studies have demonstrated that cellular reprogramming to pluripotency reverses cellular age, but alteration of the aging process ...through reprogramming has not been directly demonstrated in vivo. Here, we report that partial reprogramming by short-term cyclic expression of Oct4, Sox2, Klf4, and c-Myc (OSKM) ameliorates cellular and physiological hallmarks of aging and prolongs lifespan in a mouse model of premature aging. Similarly, expression of OSKM in vivo improves recovery from metabolic disease and muscle injury in older wild-type mice. The amelioration of age-associated phenotypes by epigenetic remodeling during cellular reprogramming highlights the role of epigenetic dysregulation as a driver of mammalian aging. Establishing in vivo platforms to modulate age-associated epigenetic marks may provide further insights into the biology of aging.
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•Partial reprogramming erases cellular markers of aging in mouse and human cells•Induction of OSKM in progeria mice ameliorates signs of aging and extends lifespan•In vivo reprogramming improves regeneration in 12-month-old wild-type mice
Cellular reprogramming by transient expression of Yamanaka factors ameliorates age-associated symptoms, prolongs lifespan in progeroid mice, and improves tissue homeostasis in older mice.
COVID‐19 is novel infectious disease with an evolving understanding of its epidemiology and clinical manifestations. Immunocompromised patients often present atypical presentations of viral diseases. ...Herein we report a case of a COVID‐19 infection in a solid organ transplant recipient, in which the first clinical symptoms were of gastrointestinal viral disease and fever, which further progressed to respiratory symptoms in 48 hours. In these high risk populations, protocols for screening for SARS‐Cov2 may be needed to be re‐evaluated.
The authors report an atypical presentation of COVID‐19 infection in a kidney transplant recipient, demonstrating the relevance of screening in a high risk population.
This phase 3 trial tested inotersen, a modified oligonucleotide that targets
TTR
messenger RNA, in the treatment of hereditary transthyretin amyloidosis, a disease in which misfolded transthyretin ...proteins are deposited in peripheral nerves and other tissues.
Targeted genome editing via engineered nucleases is an exciting area of biomedical research and holds potential for clinical applications. Despite rapid advances in the field, in vivo targeted ...transgene integration is still infeasible because current tools are inefficient, especially for non-dividing cells, which compose most adult tissues. This poses a barrier for uncovering fundamental biological principles and developing treatments for a broad range of genetic disorders. Based on clustered regularly interspaced short palindromic repeat/Cas9 (CRISPR/Cas9) technology, here we devise a homology-independent targeted integration (HITI) strategy, which allows for robust DNA knock-in in both dividing and non-dividing cells in vitro and, more importantly, in vivo (for example, in neurons of postnatal mammals). As a proof of concept of its therapeutic potential, we demonstrate the efficacy of HITI in improving visual function using a rat model of the retinal degeneration condition retinitis pigmentosa. The HITI method presented here establishes new avenues for basic research and targeted gene therapies.
Human pluripotent stem cell-derived kidney organoids recapitulate developmental processes and tissue architecture, but intrinsic limitations, such as lack of vasculature and functionality, have ...greatly hampered their application. Here we establish a versatile protocol for generating vascularized three-dimensional (3D) kidney organoids. We employ dynamic modulation of WNT signaling to control the relative proportion of proximal versus distal nephron segments, producing a correlative level of vascular endothelial growth factor A (VEGFA) to define a resident vascular network. Single-cell RNA sequencing identifies a subset of nephron progenitor cells as a potential source of renal vasculature. These kidney organoids undergo further structural and functional maturation upon implantation. Using this kidney organoid platform, we establish an in vitro model of autosomal recessive polycystic kidney disease (ARPKD), the cystic phenotype of which can be effectively prevented by gene correction or drug treatment. Our studies provide new avenues for studying human kidney development, modeling disease pathogenesis, and performing patient-specific drug validation.
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•Modulation of WNT generates vascularized and segmentally patterned kidney organoids•Single-cell analysis identifies a non-conventional origin of renal vasculature•Structural and functional maturation of kidney organoids occurs upon implantation•Cystic kidney organoids from ARPKD iPSCs enable personalized drug validation
Human PSC-derived organoids are an amenable platform for understanding human development and diseases despite numerous limitations. Low et al. establish a versatile platform for generating vascularized and patterned kidney organoids. Using this platform, they identified a non-conventional origin of renal vasculature and recapitulated ARPKD cystogenesis in vitro.
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