Somatic reprogramming of glia into neurons is a potentially promising approach for the replacement of neurons lost to injury or neurodegenerative disorders. Knockdown of the polypyrimidine tract-binding protein Ptbp1 has been recently reported to induce efficient conversion of retinal Mϋller glia and brain astrocytes into functional neurons. However, genetic analysis of Ptbp1 function in adult glia has not been conducted. Here, we use a combination of genetic lineage tracing, scRNA-Seq, and electrophysiological analysis to show that specific deletion of Ptbp1 in adult retinal Mϋller glia and brain astrocytes does not lead to any detectable level of glia-to-neuron conversion. Few changes in gene expression are observed in glia following Ptbp1 deletion, and glial identity is maintained. These findings highlight the importance of using genetic manipulation and lineage tracing methods in studying cell type conversion.
The objective of this study is to describe the clinical utility and morphologic characteristics of peripheral vitreoretinal interface abnormalities with spectral domain optical coherence tomography (SD-OCT). A prospective imaging analysis of 43 patients with peripheral vitreoretinal interface abnormalities seen on binocular indirect examination with scleral indentation was done. SD-OCT was evaluated for image quality and structural findings. Laser retinopexy was performed to surround all retinal breaks containing a full-thickness component via SD-OCT. Acceptable image quality for inclusion was obtained in 39/43 (91%) patients. Mean age was 41 ± 22 years, and mean follow-up was 14 ± 1.6 months. Decision to treat was altered following SD-OCT in 5% of the patients. Two cases of previously diagnosed operculated holes were found on SD-OCT to be partial-thickness operculated breaks or focal operculated schisis. Peripheral SD-OCT is a reliable and useful technique to examine the structural features of vitreoretinal interface abnormalities in vivo. This imaging modality is useful in the clinical management of suspected retinal breaks identified with indirect ophthalmoscopy.
Direct reprogramming of retinal Müller glia is a promising avenue for replacing photoreceptors and retinal ganglion cells lost to retinal dystrophies. However, questions have recently been raised about the accuracy of studies claiming efficient glia-to-neuron reprogramming in retina that were conducted using GFAP mini promoter-driven adeno-associated virus (AAV) vectors. In this study, we have addressed these questions using GFAP mini promoter-driven AAV constructs to simultaneously overexpress the mCherry reporter and candidate transcription factors predicted to induce glia-to-neuron conversion, in combination with prospective genetic labeling of retinal Müller glia using inducible Cre-dependent GFP reporters. We find that, while control GFAP-mCherry constructs express faithfully in Müller glia, 5 out of 7 transcription factor overexpression constructs tested are predominantly expressed in amacrine and retinal ganglion cells. These findings demonstrate strong insert-dependent effects on AAV-based GFAP mini promoter specificity that preclude its use in inferring cell lineage relationships when studying glia-to-neuron conversion in retina.
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