Biology subjects

McNally, M. M.

Publications and source records attributed to McNally, M. M..

5 recordsLinked to original sources

bioRxiv2025

Development of an image-guided non-vitrectomy subretinal access approach for trans-scleral cell and gene therapy delivery

PurposeRegenerative therapies for retinal diseases include cell and gene therapy modalities that are targeted to the subretinal space. Several recent clinical trials have shown that the morbidity of surgical access is the major limitation of safe subretinal space delivery. We aimed to develop an image-guided procedure for minimally invasive subretinal access (MISA) as a platform to deliver therapeutic agents for the treatment of degenerative retinal diseases. MethodsWe engineered prototypes of a novel common-path swept source optical coherence tomography (CP-SSOCT)-enabled needle, coaxial guide (COG), and subretinal access cannula (SAC). We pilot tested the MISA procedure in ex vivo bovine eyes and in vivo porcine ocular surgery. ResultsA- and M-mode scan recordings of ex vivo and in vivo animal eye models demonstrated that CP-SSOCT imaging from the scleral side (ab externo) was capable of identifying the retinal laminae and the sub-retinal space. We show results from in vivo porcine MISA surgeries (N=4) using the novel CP-SSOCT-enabled sub-retinal injection needle, COG, and SAC through the transscleral approach. The MISA approach enabled subretinal device placement in the posterior pole, however, cases of retinal incarceration and retinal perforation were encountered. ConclusionsWe describe a novel CP-SSOCT-guided subretinal access approach that, with further optimization, may be useful in regenerative retinal surgery.

bioengineering↗

bioRxiv2022

Cellular and Fibrillar Collagen Analyses in an Animal Model of Retinal Detachment-Related Proliferative Vitreoretinopathy Reveals a Defined Transition to Chronic Fibrosis

PurposeProliferative vitreoretinopathy (PVR) is the most common cause of failure of surgically repaired rhegmatogenous retinal detachment (RRD). Chemically-induced and cell-injection PVR models do not fully simulate the clinical characteristics of PVR in the post-RRD context. There is an unmet need for translational models in which to study mechanisms and treatments specific to RRD-PVR. MethodsRRD-PVR was induced in adult Dutch Belted rabbits. Posterior segments of enucleated globes were fixed or processed for RNA-Seq at 6 hours and 2, 7, 14, and 35 days post-induction. Histochemical staining and immunolabeling for glial fibrillary acidic protein (GFAP), alpha smooth muscle actin (SMA), vascular endothelial growth factor receptor 2 (VEGFR2), CD68, and retinal pigment epithelium 65 kDa protein (RPE65) were performed, and labeling intensity was scored. Single cell RNA sequencing was performed. ResultsAcute histopathologic changes included intravitreal and intraretinal hemorrhage, leukocytic vitritis, chorioretinitis, and retinal rarefaction. Chronic lesions showed retinal atrophy, gliosis, fibrotic subretinal membranes, and epiretinal fibrovascular proliferation. Fibrillar collagen was present in the fibrocellular and fibrovascular membranes in chronic lesions. Moderate to strong labeling of glia and vasculature was detected in chronic lesions. At day 14, most cells profiled by single cell sequencing were identified as Muller glia and microglia, consistent with immunolabeling. Expression of several fibrillar collagen genes were upregulated in chronic lesions. ConclusionsHistologic and transcriptional features of this rabbit model simulate important features of human RRD-PVR, including the transition to chronic intra and periretinal fibrosis. This high-fidelity in vivo model of RRD-PVR will enable further research on targeted treatment interventions.

pathology↗

bioRxiv2022

Comparative analysis of single-cell and single-nucleus RNA-sequencing in a rabbit model of retinal detachment-related proliferative vitreoretinopathy.

Structured AbstractO_ST_ABSPurposeC_ST_ABSProliferative vitreoretinopathy (PVR) is the most common cause of failure of retinal reattachment surgery and the molecular changes leading to this aberrant wound healing process is currently unknown. We aimed to study PVR pathogenesis using single-cell transcriptomics to dissect cellular heterogeneity in a rabbit PVR model. MethodsPVR was induced unilaterally in Dutch Belted rabbits. At different timepoints following PVR induction, retinas were dissociated into either cells or nuclei suspension and processed for single-cell or single-nucleus RNA sequencing (scRNA-seq or snRNA-seq). ResultsscRNA-Seq and snRNA-Seq were conducted on retinas at 4 hours and 14 days after disease induction. While the capture rate of unique molecular identifiers (UMI) and genes were greater in scRNA-seq samples, overall gene expression profiles of individual cell types were highly correlated between scRNA-seq and snRNA-seq. A major disparity between the two sequencing modalities is the cell type capture rate, however, with glial cell types over-represented in scRNA-seq, and inner retinal neurons were enriched by snRNA-seq. Furthermore, fibrotic Muller glia were over-represented in snRNA-seq samples, while reactive Muller glia were in scRNA-seq samples. Trajectory analyses were similar between the two methods, allowing for the combined analysis of the scRNA-seq and snRNA-seq datasets. ConclusionsThese findings highlight limitations of both scRNA-seq and snRNA-seq analysis and imply that use of both techniques can more accurately identify transcriptional networks critical for aberrant fibrogenesis in PVR.

neuroscience↗

bioRxiv2022

Transretinal migration of astrocytes and brain/spinal cord-like cells arising from transplanted human retinal organoids.

Human retinal organoid transplantation can potentially restore vision in patients with degenerative retinal diseases. How the recipient retina regulates the maturation, fate specification, and migration of transplanted organoid cells is unknown. We transplanted human retinal organoid-derived cells into photoreceptor-deficient mice, conducted histology and single-cell RNA sequencing analyses, and observed two main classes of graft-derived cells. The first class consisted of retinal astrocytes and brain/spinal cord-like neural precursors, absent or rare in cultured organoids, that migrated into all recipient retinal layers and traveled long distances. The second class consisted of retinal progenitor-derived cells, including rods and cones, that remained in the subretinal space and matured more rapidly than photoreceptors in culture. These data suggest that the recipient subretinal space promotes the maturation of transplanted photoreceptors while inducing or expanding migratory cell populations that are not normally derived from retinal progenitors. These findings have important implications for cell-based treatment of retinal diseases.

neuroscience↗

bioRxiv2019

Quantifiable In Vivo Imaging Biomarkers of Retinal Regeneration by Photoreceptor Cell Transplantation

PurposeShort-term improvements in retinal anatomy are known to occur in preclinical models of photoreceptor transplantation. However, correlative changes over the long term are poorly understood. We aimed to develop a quantifiable imaging biomarker grading scheme, using non-invasive multimodal confocal scanning laser ophthalmoscopy (cSLO) imaging, to enable serial evaluation of photoreceptor transplantation over the long term. MethodsYellow-green fluorescent microspheres were transplanted into the vitreous cavity and/or subretinal space of C57/BL6J mice. Photoreceptor cell suspensions or sheets from rhodopsin-green fluorescent protein mice were transplanted subretinally, into either NOD.CB17-Prkdcscid/J or C3H/HeJ-Pde6brd1 mice. Multimodal cSLO imaging was performed serially for up to three months after transplantation. Imaging biomarkers were scored, and a grade was defined for each eye by integrating the scores. Image grades were correlated with immunohistochemistry (IHC) data. ResultsMultimodal imaging enabled the extraction of quantitative imaging biomarkers including graft size, GFP intensity, graft length, on-target graft placement, intra-graft lamination, hemorrhage, retinal atrophy, and peri-retinal proliferation. Migration of transplanted material was observed. Changes in biomarker scores and grades were detected in 13/16 and 7/16 eyes, respectively. A high correlation was found between image grades and IHC parameters. ConclusionsSerial evaluation of multiple imaging biomarkers, when integrated into a per-eye grading scheme, enabled comprehensive tracking of longitudinal changes in photoreceptor cell grafts over time. The application of systematic multimodal in vivo imaging could be useful in increasing the efficiency of preclinical retinal cell transplantation studies in rodents and other animal models.

neuroscience↗