Here, developmental regulation of deiodinases DIO2 and DIO3 were identified as main regulators of thyroid hormone dependent sequential cone subtype specification in human retinal organoids. Either complete loss of thyroid hormone signaling or non-physiologically high thyroid hormone levels completely suppressed either medium and long wavelength cones or short wavelength cones, respectively.
Pluripotent stem cells (PSCs) offer an exciting resource for probing human biology; however, gene-editing efficiency remains relatively low in many cell types, including stem cells. Gene-editing using the CRISPR-Cas9 system offers an attractive solution that improves upon previous gene-editing approaches; however, like other technologies, off-target mutagenesis remains a concern. High-fidelity Cas9 variants greatly reduce off-target mutagenesis and offer a solution to this problem. To evaluate their utility as part of a cell-based gene-editing platform, human PSC lines were generated with a high-fidelity (HF) tetracycline-inducible engineered Streptococcus pyogenes SpCas9 (HF-iCas9) integrated into the AAVS1 safe harbor locus. By engineering cells with controllable expression of Cas9, we eliminated the need to include a large Cas9-expressing plasmid during cell transfection. Delivery of genetic cargo was further optimized by packaging DNA targeting guide RNAs (gRNAs) and donor fragments into a single plasmid backbone. The potential of homology-directed repair (HDR) based gene knock-in at the CLYBL safe harbor site and endogenous SOX2 and SIX6 genes were demonstrated. Moreover, we used non-homologous end-joining (NHEJ) for gene knockout of disease-relevant alleles. These high-fidelity CRISPR tools and the resulting HF-iCas9 cell lines will facilitate the production of cell-type reporters and mutants across different genetic backgrounds.
Background: Gene delivery can potentially be used as a therapeutic for treating genetic diseases, including neurodegenerative diseases, as well as an enabling technology for regenerative medicine. A central challenge in many gene delivery applications is having a safe and effective delivery method. We evaluated the use of a biodegradable poly(beta-amino ester) nanoparticle-based nonviral protocol and compared this with an electroporation-based approach to deliver episomal plasmids encoding reprogramming factors for generation of human induced pluripotent stem cells (hiPSCs) from human fibroblasts. Methods: A polymer library was screened to identify the polymers most promising for gene delivery to human fibroblasts. Feeder-independent culturing protocols were developed for nanoparticle-based and electroporation-based reprogramming. The cells reprogrammed by both polymeric nanoparticle-based and electroporation-based nonviral methods were characterized by analysis of pluripotency markers and karyotypic stability. The hiPSC-like cells were further differentiated toward the neural lineage to test their potential for neurodegenerative retinal disease modeling. Results: 1-(3-aminopropyl)-4-methylpiperazine end-terminated poly(1,4-butanediol diacrylate-co-4-amino-1-butanol) polymer (B4S4E7) self-assembled with plasmid DNA to form nanoparticles that were more effective than leading commercially available reagents, including Lipofectamine ® 2000, FuGENE ® HD, and 25 kDa branched polyethylenimine, for nonviral gene transfer. B4S4E7 nanoparticles showed effective gene delivery to IMR-90 human primary fibroblasts and to dermal fibroblasts derived from a patient with retinitis pigmentosa, and enabled coexpression of exogenously delivered genes, as is needed for reprogramming. The karyotypically normal hiPSC-like cells generated by conventional electroporation, but not by poly(beta-amino ester) reprogramming, could be differentiated toward the neuronal lineage, specifically pseudostratified optic cups. Conclusion: This study shows that certain nonviral reprogramming methods may not necessarily be safer than viral approaches and that maximizing exogenous gene expression of reprogramming factors is not sufficient to ensure successful reprogramming. Keywords: poly(beta-amino ester) nanoparticles, reprogramming, human fibroblasts, induced pluripotent stem cells
Müller glia are non-neuronal support cells that play a vital role in the homeostasis of the eye. Their radial-oriented processes span the width of the retina and respond to injury through a cellular response that can be detrimental or protective depending on the context. In some species, protective responses include the expression of stem cell-like genes which help to fuel new neuron formation and even restoration of vision. In many lower vertebrates including fish and amphibians, this response is well documented, however, in mammals it is severely limited. The remarkable plasticity of cellular reprogramming in lower vertebrates has inspired studies in mammals for repairing the retina and restoring sight, and recent studies suggest that mammals are also capable of regeneration, albeit to a lesser degree. Endogenous regeneration, whereby new retinal neurons are created from existing support cells, offers an exciting alternative approach to existing tissue transplant, gene therapy, and neural prosthetic approaches being explored in parallel. This review will highlight the role of Müller glia during retinal injury and repair. In the end, prospects for advancing retinal regeneration research will be considered.
Objective Previous studies indicate an increased short-term and long-term mortality from major cancer surgery performed towards the end of the working week or during the weekend. We hypothesised that the prognosis after major cancer surgery is also negatively influenced by surgery conducted during holiday periods. Setting Population-based nationwide Swedish cohort study. Participants Patients undergoing oesophagectomy for oesophageal cancer between 1987 and 2010. Among 1820 included patients, 206 (11.3%) and 373 (20.5%) patients were operated on during narrow and wide holiday periods, respectively. Interventions Narrow (7 weeks) and wide (14 weeks) Swedish holiday periods. Primary and secondary outcome measures 90-day all-cause, 5-year all-cause and 5-year disease-specific mortality. Results Narrow holiday period did not increase all-cause 90-day (HR=0.84, 95% CI 0.53 to 1.33), all-cause 5-year (HR=1.01, 95% CI 0.85 to 1.21) or disease-specific 5-year mortality (HR=1.04, 95% CI 0.87 to 1.26). Similarly, wide holiday period did not increase the risk of 90-day (HR=0.79, 95% CI 0.55 to 1.13), all-cause 5-year (HR=0.96, 95% CI 0.84 to 1.1) or disease-specific 5-year mortality (HR=1.03, 95% CI 0.89 to 1.19). Conclusions No measurable effects of holiday periods on short-term or longer term mortality following surgery for oesophageal cancer were observed in this population-based study, indicating that an adequate surgical experience was maintained during holiday periods.
Cohort studies, mainly based on questionnaires and interviews, have reported high rates of reflux recurrence after antireflux surgery, which may have contributed to a decline in its use. Reflux recurrence after laparoscopic antireflux surgery has not been assessed in a long-term population-based study of unselected patients.
Objectives
To determine the risk of reflux recurrence after laparoscopic antireflux surgery and to identify risk factors for recurrence.
Design and Setting
Nationwide population-based retrospective cohort study in Sweden between January 1, 2005, and December 31, 2014, based on all Swedish health care and including 2655 patients who underwent laparoscopic antireflux surgery according to the Swedish Patient Registry. Their records were linked to the Swedish Causes of Death Registry and Prescribed Drug Registry.
Exposures
Primary laparoscopic antireflux surgery due to gastroesophageal reflux disease in adults (>18 years).
Main Outcomes and Measures
The outcome was recurrence of reflux, defined as use of antireflux medication (proton pump inhibitors or histamine2receptor antagonists for >6 months) or secondary antireflux surgery. Multivariable Cox regression was used to assess risk factors for reflux recurrence.
Results
Among all 2655 patients who underwent antireflux surgery (median age, 51.0 years; interquartile range, 40.0-61.0 years; 1354 men [51.0%]) and were followed up for a median of 5.6 years, 470 patients (17.7%) had reflux recurrence; 393 (83.6%) received long-term antireflux medication and 77 (16.4%) underwent secondary antireflux surgery. Risk factors for reflux recurrence included female sex (hazard ratio [HR], 1.57 [95% CI, 1.29-1.90]; 286 of 1301 women [22.0%] and 184 of 1354 men [13.6%] had recurrence of reflux), older age (HR, 1.41 [95% CI, 1.10-1.81] for age ≥61 years compared with ≤45 years; recurrence among 156 of 715 patients and 133 of 989 patients, respectively), and comorbidity (HR, 1.36 [95% CI, 1.13-1.65] for Charlson comorbidity index score ≥1 compared with 0; recurrence among 180 of 804 patients and 290 of 1851 patients, respectively). Hospital volume of antireflux surgery was not associated with risk of reflux recurrence (HR, 1.09 [95% CI, 0.77-1.53] for hospital volume ≤24 surgeries compared with ≥76 surgeries; recurrence among 38 of 266 patients [14.3%] and 271 of 1526 patients [17.8%], respectively).
Conclusions and Relevance
Among patients who underwent primary laparoscopic antireflux surgery, 17.7% experienced recurrent gastroesophageal reflux requiring long-term medication use or secondary antireflux surgery. Risk factors for recurrence were older age, female sex, and comorbidity. Laparoscopic antireflux surgery was associated with a relatively high rate of recurrent gastroesophageal reflux disease requiring treatment, diminishing some of the benefits of the operation.
Ras-like without CAAX 2 (RIT2), a member of the Ras superfamily of small guanosine triphosphatases, is involved in regulating neuronal function. RIT2 is a unique member of the Ras family in that RIT2 is preferentially expressed in various neurons, including retinal neurons. The mechanisms that regulate RIT2 expression in neurons were studied.Reverse transcription-quantitative PCR (RT-qPCR), immunohistochemistry, western blotting, bioinformatic prediction, electrophoretic mobility shift assay (EMSA), and cell transfection methods were used.With immunohistochemistry of the mouse retina, RIT2 protein was detected in the ganglion cell layer (GCL), inner plexiform layer, inner nuclear layer, and outer plexiform layer, with the strongest staining in the GCL and the inner plexiform layer. RT-qPCR combined with laser capture microdissection detected Rit2 messenger RNA in the GCL and the inner nuclear layer. Western blot analysis showed a large increase in the RIT2 protein in the retina during maturation from newborn to adult. Transient transfection identified the 1.3 kb upstream region of human RIT2 as capable of driving expression in neuronal cell lines. Based on the known expression pattern and biological activity, we hypothesized that POU4 family factors might modulate RIT2 expression in retinal ganglion cells (RGCs). Bioinformatic analyses predicted six POU4 factor-binding sites within the 1.3 kb human RIT2 promoter region. EMSA analyses showed binding of POU4 proteins to three of the six predicted sites. Cotransfection with expression vectors demonstrated that POU4 proteins can indeed modulate the human RIT2 promoter, and that ISL1, a LIM homeodomain factor, can further modulate the activity of the POU4 factors.These studies confirm the expression of RIT2 in retinal neuronal cells, including RGCs, begin to reveal the mechanisms responsible for neuronal expression of RIT2, and suggest a role for the POU4 family factors in modulating RIT2 expression in RGCs.
