Predicting reprogramming-related gene expression from cell morphology in human induced pluripotent stem cells.

Purification is essential before differentiating human induced pluripotent stem cells (hiPSCs) into cells that fully express particular differentiation marker genes. High-quality iPSC clones are typically purified through gene expression profiling or visual inspection of the cell morphology; however, the relationship between the two methods remains unclear. We investigated the relationship between gene expression levels and morphology by analyzing live-cell, phase-contrast images and mRNA profiles collected during the purification process. We employed these data and an unsupervised image feature extraction method to build a model that predicts gene expression levels from morphology. As a benchmark, it was confirmed that the method can predict the gene expression levels from tissue images for cancer genes, performing as well as state-of-the-art methods. We then applied the method to iPSCs and identified two genes that are well predicted from cell morphology. Although strong batch (or possibly donor) effects resulting from the reprogramming process preclude the ability to use the same model to predict across batches, prediction within a reprogramming batch is sufficiently robust to provide a practical approach for estimating expression levels of a few genes and monitoring the purification process.

[Pharmacological and clinical profile of Onasemnogene Aveparvovec, the first gene therapy for spinal muscular atrophy (SMA)].

Onasemnogene abeparvovec (Zolgensma®; formerly AVXS-101) is a one-time gene therapy designed to address the genetic root cause of spinal muscular atrophy (SMA) by replacing the function of the missing or nonworking SMN1 gene via an adeno-associated AAV9 viral vector. On March 19, 2020, the Japanese Ministry of Health, Labor and Welfare approved onasemnogene abeparvovec for the treatment of SMA patients <2 years of age, including presymptomatic patients with a genetic diagnosis. Patients must be negative for elevated anti-AAV9 antibodies. Onasemnogene abeparvovec is administered through a single intravenous infusion, delivering a new working copy of the SMN gene into a patient's cells. Intravenous administration of onasemnogene abeparvovec to SMA model mice resulted in sustained expression of survival motor neuron (SMN) protein, weight gain, improvement of motor function, and prolongation of survival. Its clinical efficacy and safety have been demonstrated through the Phase I START and Phase III STR1VE-US, STR1VE-EU, and SPR1NT trials, and their long-term extension studies. SMA and presymptomatic patients treated with onasemnogene abeparvovec have achieved rates of survival not observed in the natural history of SMA. Treatment has led to rapid motor function improvement, often within one month of dosing, and developmental milestone achievement, including the ability to sit without support. The most commonly observed adverse effects after treatment were elevated liver enzymes, which often resolved with a course of prednisolone, and vomiting. This review discusses the rationale underlying gene replacement therapy for SMA, and describes the basic science, clinical trial experience, and use of onasemnogene abeparvovec.