Biology subjects

Lushington, C.

Publications and source records attributed to Lushington, C..

3 recordsLinked to original sources

bioRxiv2026

Engineered trophoblast organoids recapitulate molecular and functional features of preeclampsia

Preeclampsia is a major pregnancy complication driven by placental dysfunction, yet research is limited by reliance on patient-derived tissues and models that do not fully capture human disease. Here, we develop a genetically engineered human trophoblast organoid model of preeclampsia that can be generated without access to placental tissue. Using a CRISPR-based Prime Integrase strategy, we engineered induced trophoblast stem cells to express the preeclampsia-associated soluble fms-like tyrosine kinase-1 (sFlt-1) exon 15a isoform. Engineered organoids showed a transcriptional shift towards primary preeclamptic placentae and developed several features of disease. These included reduced PlGF, increased IL-6 and soluble endoglin, oxidative stress, impaired growth and an elevated sFlt-1/PlGF ratio comparable to primary preeclamptic trophoblast organoids. These broader changes were not reproduced by adding recombinant human sFlt-1 to control organoids. Conditioned media from engineered organoids impaired endothelial network formation, demonstrating a functional effect of the altered trophoblast secretome. Treatment with sulfasalazine and metformin also restored angiogenic balance and organoid growth. Together, these findings establish a tractable human model that reproduces molecular and functional features of preeclampsia and provides a platform to study disease mechanisms and test potential therapies.

cell biology↗

bioRxiv2024

Enhancing gRNA Transcript levels by Reducing the Scaffold Poly-T Tract for Optimal SpCas9- and SaCas9-mediated Gene Editing

Ensuring sufficient gRNA transcript levels is critical for obtaining optimal CRISPR-Cas9 gene editing efficiency. The standard gRNA scaffold contains a sequence of four thymine nucleotides (4T), which is known to inhibit transcription from Pol III promoters such as the U6 promoter. Our study showed that using standard plasmid transfection protocols, the presence of these 4Ts did not significantly affect editing efficiency, as most of the gRNAs tested (55 gRNAs) achieved near-perfect editing outcomes. We observed that gRNAs with lower activity were T-rich and had reduced gRNA transcript levels. However, this issue can be effectively resolved by increasing transcript levels, which can be readily achieved by shortening the 4T sequences. In this study, we demonstrated this by modifying the sequences to 3TC. Although the 3TC scaffold modification did not improve editing efficiency for already efficient gRNAs when high vector quantities were available, it proved highly beneficial under conditions of limited vector availability, where the 3TC scaffold yielded higher editing efficiency. Additionally, we demonstrated that the 3TC scaffold is compatible with SpCas9 high-fidelity variants and ABEmax base editing, enhancing their editing efficiency. Another commonly used natural Cas9 variant, SaCas9, also benefited from the 3TC scaffold sequence modification, which increased gRNA transcription and subsequently improved editing activity. This modification was applied to the EDIT-101 therapeutic strategy, where it demonstrated marked improvements in performance. This study highlights the importance of shortening the 4T sequences in the gRNA scaffold to optimize gRNA transcript expression for enhanced CRISPR-Cas9 gene editing efficiency. This optimization is particularly important for therapeutic applications, where the quantity of vector is often limited, ensuring more effective and optimal outcomes.

molecular biology↗

bioRxiv2021

Optimized nickase- and nuclease-based prime editing in human and mouse cells

Precise genomic modification using prime editing (PE) holds enormous potential for research and clinical applications. Currently, the delivery of PE components to mammalian cell lines requires multiple plasmid vectors. To overcome this limitation, we generated all-in-one prime editing (PEA1) constructs that carry all the components required for PE, along with a selection marker. We tested these constructs (with selection) in HEK293T, K562, HeLa and mouse embryonic stem (ES) cells. We discovered that PE efficiency in HEK293T cells was much higher than previously observed, reaching up to 95% (mean 67%). The efficiency in K562 and HeLa cells, however, remained low. To improve PE efficiency in K562 and HeLa, we generated a nuclease prime editor and tested this system in these cell lines as well as mouse ES cells. PE-nuclease greatly increased prime editing initiation, however, installation of the intended edits was often accompanied by extra insertions derived from the repair template. Finally, we show that zygotic injection of the nuclease prime editor can generate correct modifications in mouse fetuses with up to 100% efficiency. In summary, PE-nuclease and the PEA1 plasmids provide new tools to generate intended edits with high efficiency.

molecular biology↗