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Seeing Neurodegeneration in a New Light Using Genetically Encoded Fluorescent Biosensors and iPSCs. Int J Mol Sci 2023; 24:ijms24021766. [PMID: 36675282 PMCID: PMC9861453 DOI: 10.3390/ijms24021766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 01/11/2023] [Accepted: 01/12/2023] [Indexed: 01/18/2023] Open
Abstract
Neurodegenerative diseases present a progressive loss of neuronal structure and function, leading to cell death and irrecoverable brain atrophy. Most have disease-modifying therapies, in part because the mechanisms of neurodegeneration are yet to be defined, preventing the development of targeted therapies. To overcome this, there is a need for tools that enable a quantitative assessment of how cellular mechanisms and diverse environmental conditions contribute to disease. One such tool is genetically encodable fluorescent biosensors (GEFBs), engineered constructs encoding proteins with novel functions capable of sensing spatiotemporal changes in specific pathways, enzyme functions, or metabolite levels. GEFB technology therefore presents a plethora of unique sensing capabilities that, when coupled with induced pluripotent stem cells (iPSCs), present a powerful tool for exploring disease mechanisms and identifying novel therapeutics. In this review, we discuss different GEFBs relevant to neurodegenerative disease and how they can be used with iPSCs to illuminate unresolved questions about causes and risks for neurodegenerative disease.
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Ramamurthy RM, Rodriguez M, Ainsworth HC, Shields J, Meares D, Bishop C, Farland A, Langefeld CD, Atala A, Doering CB, Spencer HT, Porada CD, Almeida-Porada G. Comparison of different gene addition strategies to modify placental derived-mesenchymal stromal cells to produce FVIII. Front Immunol 2022; 13:954984. [PMID: 36591257 PMCID: PMC9800010 DOI: 10.3389/fimmu.2022.954984] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 11/28/2022] [Indexed: 12/23/2022] Open
Abstract
Introduction Placenta-derived mesenchymal cells (PLCs) endogenously produce FVIII, which makes them ideally suited for cell-based fVIII gene delivery. We have previously reported that human PLCs can be efficiently modified with a lentiviral vector encoding a bioengineered, expression/secretion-optimized fVIII transgene (ET3) and durably produce clinically relevant levels of functionally active FVIII. The objective of the present study was to investigate whether CRISPR/Cas9 can be used to achieve location-specific insertion of a fVIII transgene into a genomic safe harbor, thereby eliminating the potential risks arising from the semi-random genomic integration inherent to lentiviral vectors. We hypothesized this approach would improve the safety of the PLC-based gene delivery platform and might also enhance the therapeutic effect by eliminating chromatin-related transgene silencing. Methods We used CRISPR/Cas9 to attempt to insert the bioengineered fVIII transgene "lcoET3" into the AAVS1 site of PLCs (CRISPR-lcoET3) and determined their subsequent levels of FVIII production, comparing results with this approach to those achieved using lentivector transduction (LV-lcoET3) and plasmid transfection (Plasmid-lcoET3). In addition, since liver-derived sinusoidal endothelial cells (LSECs) are the native site of FVIII production in the body, we also performed parallel studies in human (h)LSECs). Results PLCs and hLSECs can both be transduced (LV-lcoET3) with very high efficiency and produce high levels of biologically active FVIII. Surprisingly, both cell types were largely refractory to CRISPR/Cas9-mediated knockin of the lcoET3 fVIII transgene in the AAVS1 genome locus. However, successful insertion of an RFP reporter into this locus using an identical procedure suggests the failure to achieve knockin of the lcoET3 expression cassette at this site is likely a function of its large size. Importantly, using plasmids, alone or to introduce the CRISPR/Cas9 "machinery", resulted in dramatic upregulation of TLR 3, TLR 7, and BiP in PLCs, compromising their unique immune-inertness. Discussion Although we did not achieve our primary objective, our results validate the utility of both PLCs and hLSECs as cell-based delivery vehicles for a fVIII transgene, and they highlight the hurdles that remain to be overcome before primary human cells can be gene-edited with sufficient efficiency for use in cell-based gene therapy to treat HA.
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Affiliation(s)
- Ritu M. Ramamurthy
- Fetal Research and Therapy Program, Wake Forest Institute for Regenerative Medicine, Winston Salem, NC, United States
| | - Martin Rodriguez
- Fetal Research and Therapy Program, Wake Forest Institute for Regenerative Medicine, Winston Salem, NC, United States
| | - Hannah C. Ainsworth
- Department of Biostatistics and Data Sciences Wake Forest School of Medicine, Winston Salem, NC, United States
| | - Jordan Shields
- Department of Pediatrics, Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Emory University, Atlanta, GA, United States
| | - Diane Meares
- Department of Medicine, Hematology and Oncology, Wake Forest School of Medicine, Winston Salem, NC, United States
| | - Colin Bishop
- Fetal Research and Therapy Program, Wake Forest Institute for Regenerative Medicine, Winston Salem, NC, United States
| | - Andrew Farland
- Department of Medicine, Hematology and Oncology, Wake Forest School of Medicine, Winston Salem, NC, United States
| | - Carl D. Langefeld
- Department of Biostatistics and Data Sciences Wake Forest School of Medicine, Winston Salem, NC, United States
| | - Anthony Atala
- Fetal Research and Therapy Program, Wake Forest Institute for Regenerative Medicine, Winston Salem, NC, United States
| | - Christopher B. Doering
- Department of Pediatrics, Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Emory University, Atlanta, GA, United States
| | - H. Trent Spencer
- Department of Pediatrics, Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Emory University, Atlanta, GA, United States
| | - Christopher D. Porada
- Fetal Research and Therapy Program, Wake Forest Institute for Regenerative Medicine, Winston Salem, NC, United States
| | - Graça Almeida-Porada
- Fetal Research and Therapy Program, Wake Forest Institute for Regenerative Medicine, Winston Salem, NC, United States
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Bijlani S, Pang KM, Sivanandam V, Singh A, Chatterjee S. The Role of Recombinant AAV in Precise Genome Editing. Front Genome Ed 2022; 3:799722. [PMID: 35098210 PMCID: PMC8793687 DOI: 10.3389/fgeed.2021.799722] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 12/14/2021] [Indexed: 12/14/2022] Open
Abstract
The replication-defective, non-pathogenic, nearly ubiquitous single-stranded adeno-associated viruses (AAVs) have gained importance since their discovery about 50 years ago. Their unique life cycle and virus-cell interactions have led to the development of recombinant AAVs as ideal genetic medicine tools that have evolved into effective commercialized gene therapies. A distinctive property of AAVs is their ability to edit the genome precisely. In contrast to all current genome editing platforms, AAV exclusively utilizes the high-fidelity homologous recombination (HR) pathway and does not require exogenous nucleases for prior cleavage of genomic DNA. Together, this leads to a highly precise editing outcome that preserves genomic integrity without incorporation of indel mutations or viral sequences at the target site while also obviating the possibility of off-target genotoxicity. The stem cell-derived AAV (AAVHSCs) were found to mediate precise and efficient HR with high on-target accuracy and at high efficiencies. AAVHSC editing occurs efficiently in post-mitotic cells and tissues in vivo. Additionally, AAV also has the advantage of an intrinsic delivery mechanism. Thus, this distinctive genome editing platform holds tremendous promise for the correction of disease-associated mutations without adding to the mutational burden. This review will focus on the unique properties of direct AAV-mediated genome editing and their potential mechanisms of action.
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