Knock-in strategy at 3′-end ofCrxgene by CRISPR/Cas9 system shows the gene expression profiles during human photoreceptor differentiation

Microfluidic processing of stem cells for autologous cell replacement

Autologous photoreceptor cell replacement is one of the most promising approaches currently under development for the treatment of inherited retinal degenerative blindness. Unlike endogenous stem cell populations, induced pluripotent stem cells (iPSCs) can be differentiated into both rod and cone photoreceptors in high numbers, making them ideal for this application. That said, in addition to photoreceptor cells, state of the art retinal differentiation protocols give rise to all of the different cell types of the normal retina, the majority of which are not required and may in fact hinder successful photoreceptor cell replacement. As such, following differentiation photoreceptor cell enrichment will likely be required. In addition, to prevent the newly generated photoreceptor cells from suffering the same fate as the patient's original cells, correction of the patient's disease‐causing genetic mutations will be necessary. In this review we discuss literature pertaining to the use of different cell sorting and transfection approaches with a focus on the development and use of novel next generation microfluidic devices. We will discuss how gold standard strategies have been used, the advantages and disadvantages of each, and how novel microfluidic platforms can be incorporated into the clinical manufacturing pipeline to reduce the complexity, cost, and regulatory burden associated with clinical grade production of photoreceptor cells for autologous cell replacement.

Taurine rescues mitochondria-related metabolic impairments in the patient-derived induced pluripotent stem cells and epithelial-mesenchymal transition in the retinal pigment epithelium

Mitochondria participate in various metabolic pathways, and their dysregulation results in multiple disorders, including aging-related diseases. However, the metabolic changes and mechanisms of mitochondrial disorders are not fully understood. Here, we found that induced pluripotent stem cells (iPSCs) from a patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) showed attenuated proliferation and survival when glycolysis was inhibited. These deficits were rescued by taurine administration. Metabolomic analyses showed that the ratio of the reduced (GSH) to oxidized glutathione (GSSG) was decreased; whereas the levels of cysteine, a substrate of GSH, and oxidative stress markers were upregulated in MELAS iPSCs. Taurine normalized these changes, suggesting that MELAS iPSCs were affected by the oxidative stress and taurine reduced its influence. We also analyzed the retinal pigment epithelium (RPE) differentiated from MELAS iPSCs by using a three-dimensional culture system and found that it showed epithelial mesenchymal transition (EMT), which was suppressed by taurine. Therefore, mitochondrial dysfunction caused metabolic changes, accumulation of oxidative stress that depleted GSH, and EMT in the RPE that could be involved in retinal pathogenesis. Because all these phenomena were sensitive to taurine treatment, we conclude that administration of taurine may be a potential new therapeutic approach for mitochondria-related retinal diseases.

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iPS cell lines were derived from a MELAS patient with the mtDNA A3243G mutation.

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Decreased proliferation and survival of MELAS iPSCs were rescued by taurine.

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Reduction in GSH/GSSG ratio in MELAS iPSCs was suppressed by taurine.

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EMT in MELAS iPSC-derived retinal pigment epithelium was suppressed by taurine.

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Oxidative stress markers in MELAS iPSCs and RPE were suppressed by taurine.

Comparative Transcriptome Profiling of the Loaches Triplophysa bleekeri and Triplophysa rosa Reveals Potential Mechanisms of Eye Degeneration

Eye degeneration is one of the most obvious characteristics of organisms restricted to subterranean habitats. In cavefish, eye degeneration has evolved independently numerous times and each process is associated with different genetic mechanisms. To gain a better understanding of these mechanisms, we compared the eyes of adult individuals of the cave loach Triplophysa rosa and surface loach Triplophysa bleekeri. Compared with the normal eyes of the surface loach, those of the cave loach were found to possess a small abnormal lens and a defective retina containing photoreceptor cells that lack outer segments. Sequencing of the transcriptomes of both species to identify differentially expressed genes (DEGs) and genes under positive selection revealed 4,802 DEGs and 50 genes under positive selection (dN/dS > 1, FDR < 0.1). For cave loaches, we identified one Gene Ontology category related to vision that was significantly enriched in downregulated genes. Specifically, we found that many of the downregulated genes, including pitx3, lim2, crx, gnat2, rx1, rho, prph2, and β|γ-crystallin are associated with lens/retinal development and maintenance. However, compared with those in the surface loach, the lower dS rates but higher dN rates of the protein-coding sequences in T. rosa indicate that changes in amino acid sequences might be involved in the adaptation and visual degeneration of cave loaches. We also found that genes associated with light perception and light-stimulated vision have evolved at higher rates (some genes dN/dS > 1 but FDR > 0.1). Collectively, the findings of this study indicate that the degradation of cavefish vision is probably associated with both gene expression and amino acid changes and provide new insights into the mechanisms underlying the degeneration of cavefish eyes.

Spatiotemporal imaging documented the maturation of the cardiomyocytes from human induced pluripotent stem cells

OBJECTIVES

Cardiomyocytes derived from human induced pluripotent stem cells are a promising source of cells for regenerative medicine. However, contractions in such derived cardiomyocytes are often irregular and asynchronous, especially at early stages of differentiation. This study aimed to determine the differentiation stage of initiation of synchronized and regular contractions, using spatiotemporal imaging and physiological and genetic analyses.

METHODS

Knock-in human induced pluripotent stem cell lines were established with clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeats-associated protein 9 to analyze cardiac and pacemaker cell maturation. Time-frequency analysis and Ca²⁺ imaging were performed, and the expression of related proteins and specific cardiac/pacemaker mRNAs in contracting embryoid bodies was analyzed at various differentiation stages.

RESULTS

Time-frequency analysis and Ca²⁺ imaging revealed irregular, asynchronous contractions at the early stage of differentiation with altered electrophysiological properties upon differentiation. Genes associated with electrophysiological properties were upregulated after 70 days of culturing in differentiation media, whereas pacemaker genes were initially upregulated during the early stage and downregulated at the later stage.

CONCLUSIONS

A differentiation period >70 days is required for adequate development of cardiac elements including ion channels and gap junctions and for sarcomere maturation.

Guiding Lights in Genome Editing for Inherited Retinal Disorders: Implications for Gene and Cell Therapy

Inherited retinal dystrophies (IRDs) are a leading cause of visual impairment in the developing world. These conditions present an irreversible dysfunction or loss of neural retinal cells, which significantly impacts quality of life. Due to the anatomical accessibility and immunoprivileged status of the eye, ophthalmological research has been at the forefront of innovative and advanced gene- and cell-based therapies, both of which represent great potential as therapeutic treatments for IRD patients. However, due to a genetic and clinical heterogeneity, certain IRDs are not candidates for these approaches. New advances in the field of genome editing using Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated protein (Cas) have provided an accurate and efficient way to edit the human genome and represent an appealing alternative for treating IRDs. We provide a brief update on current gene augmentation therapies for retinal dystrophies. Furthermore, we discuss recent advances in the field of genome editing and stem cell technologies, which together enable precise and personalized therapies for patients. Lastly, we highlight current technological limitations and barriers that need to be overcome before this technology can become a viable treatment option for patients.

Stem cells and genome editing: approaches to tissue regeneration and regenerative medicine

Understanding the basis of regeneration of each tissue and organ, and incorporating this knowledge into clinical treatments for degenerative tissues and organs in patients, are major goals for researchers in regenerative biology. Here we provide an overview of current work, from high-regeneration animal models, to stem cell-based culture models, transplantation technologies, large-animal chimeric models, and programmable nuclease-based genome-editing technologies. Three-dimensional culture generating organoids, which represents intact tissue/organ identity including cell fate and morphology are getting more general approaches in the fields by taking advantage of embryonic stem cells, induced pluripotent stem cells and adult stem cells. The organoid culture system potentially has profound impact on the field of regenerative medicine. We also emphasize that the large animal model, in particular pig model would be a hope to manufacture humanized organs in in vivo empty (vacant) niche, which now potentially allows not only appropriate cell fate identity but nearly the same property as human organs in size. Therefore, integrative and collaborative researches across different fields might be critical to the aims needed in clinical trial.