Biology subjects

Toh, W. H.

Publications and source records attributed to Toh, W. H..

7 recordsLinked to original sources

bioRxiv2026

FALCON: Closed-Loop Multi-Objective Optimization of Lipid Nanoparticles for Cell-Selective mRNA Delivery

Efficient, cell type-selective delivery of genetic payloads remains a central challenge in the development of gene and cell therapies. Lipid nanoparticles (LNPs) offer a versatile delivery platform, but their optimization is hindered by reliance on brute-force screening methods that are laborious, resource-intensive, and focus on single targets. Here, we present FALCON (Framework for Active Learning-driven Compositional Optimization of Nanoparticles), a closed-loop pipeline that leverages iterative screening, surrogate modeling, and multi-objective optimization to accelerate LNP compositional design. In B cell-targeted validation experiments, FALCON-optimized LNPs achieved a 1.8-fold increase in splenic B cell transfection in vivo compared with reference compositions. When optimized for selectivity, FALCON LNPs displayed an 84-fold improvement in selective transfection of splenic B cells over off-target liver populations and enabled spleen-tropic behavior across factorial panels of varying ionizable and helper lipid chemistries. In vaccine studies, these LNPs induced higher IgG2c antibody titers and a more Th1-biased immune profile. FALCON was also deployed to optimize LNPs for myeloid cell-selective delivery, achieving enhanced in vivo selectivity following systemic administration both across and within spleen and liver compartments. Our results establish FALCON as a useful tool for data-driven design of LNP compositions for precision gene delivery.

bioengineering↗

bioRxiv2026

Engineering age-adaptive mRNA lipid nanoparticle cancer vaccines via reprogramming systemic gene expression

Lipid nanoparticle (LNP)-based mRNA vaccines have transformed cancer immunotherapy, yet their efficacy in older individuals, who represent the majority of cancer patients, remains poorly understood. Here, we uncover a critical and previously underappreciated barrier to mRNA LNP cancer vaccine performance in aged hosts: impaired systemic transgene expression. Using the SM-102 mRNA LNPs as a benchmark formulation, we show that while local immune activation and antigen presentation at the injection site and draining lymph nodes remain largely intact with age, transgene expression in peripheral organs, including the liver, lungs, and spleen, is markedly reduced. This deficit limits the magnitude and durability of CD8 and CD4 T cell responses and substantially compromises tumour control. Transcriptomic profiling further reveals that attenuated transgene expression parallels broad attenuation of antigen processing, presentation, and activation pathways in immune cells from aged animals, implicating impaired systemic mRNA translation as a central driver of the downstream immune defects and antitumour efficacy loss. Building on these insights, we identify a rationally selected LNP formulation that reestablishes distal antigen expression across age groups as an engineering strategy to revive T cell immunity, achieving full rescue of therapeutic efficacy in aged mice without additional intervention. Together, these findings establish systemic mRNA translation as a tuneable lever of vaccine performance and highlight that optimizing LNP formulations to sustain systemic transgene expression across age groups may enable next-generation, age-adaptive mRNA vaccines for cancer and other diseases of aging.

bioengineering↗

bioRxiv2025

Crosslinking of Lipid Nanoparticles Enhances the Delivery Efficiency and Efficacy of mRNA Vaccines

Lipid nanoparticles (LNPs) have enabled the effective delivery of RNA therapeutics and mRNA vaccines. However, their broader applications are limited by the suboptimal stability and endosomal escape efficiency. Here, we present an easy-to-adopt post-assembly crosslinking approach to enhance the structural and functional stability of mRNA LNPs. By leveraging a series of cholesterol derivatives and crosslinking methods, we induce crosslinks of the lipid components following mRNA LNP assembly to form the crosslinked LNPs (cLNPs). We systematically evaluated crosslinking parameters and identified optimal conditions that enhance both the physical stability and transfection efficiency of cLNPs. Our findings demonstrate that cLNPs exhibit improved structural integrity under storage and lyophilization conditions, as well as increased extracellular stability and endosomal escape efficiency, resulting in improved performance of mRNA LNPs both in vitro and in vivo. This crosslinking strategy represents a critical advance in LNP engineering, enabling more resilient LNPs and broadening the applicability of LNP-based therapies for gene therapy and vaccine delivery. Our work lays the foundation for developing next-generation LNPs with superior stability and delivery efficiency, broadening the impact of RNA therapeutics and vaccines.

bioengineering↗

bioRxiv2023

Machine Learning Elucidates Design Features of Plasmid DNA Lipid Nanoparticles for Cell Type-Preferential Transfection

For cell and gene therapies to become more broadly accessible, it is critical to develop and optimize non-viral cell type-preferential gene carriers such as lipid nanoparticles (LNPs). Despite the effectiveness of high throughput screening (HTS) approaches in expediting LNP discovery, they are often costly, labor-intensive, and often do not provide actionable LNP design rules that focus screening efforts on the most relevant chemical and formulation parameters. Here we employed a machine learning (ML) workflow using well-curated plasmid DNA LNP transfection datasets across six cell types to maximize chemical insights from HTS studies and has achieved predictions with 5-9% error on average depending on cell type. By applying Shapley additive explanations to our ML models, we unveiled composition-function relationships dictating cell type-preferential LNP transfection efficiency. Notably, we identified consistent LNP composition parameters that enhance in vitro transfection efficiency across diverse cell types, such as ionizable to helper lipid ratios near 1:1 or 10:1 and the incorporation of cationic/zwitterionic helper lipids. In addition, several parameters were found to modulate cell type-preferentiality, including the ionizable and helper lipid total molar percentage, N/P ratio, cholesterol to PEGylated lipid ratio, and the chemical identity of the helper lipid. This study leverages HTS of compositionally diverse LNP libraries and ML analysis to understand the interactions between lipid components in LNP formulations; and offers fundamental insights that contribute to the establishment of unique sets of LNP compositions tailored for cell type-preferential transfection.

bioengineering↗

bioRxiv2022

Expression and functional evaluation of recombinant human ABO blood group antigen cleaving glycoside hydrolases α-N-acetylgalactosaminidase, α-galactosidase, and endo-β-galactosidase produced in Escherichia coli

Blood transfusions are an integral component of healthcare; however, availability of viable blood is limited by patient-donor blood type specificity, which contributes to seasonal shortages as well as shortages worldwide, especially in developing countries, and during pandemics or natural disasters. Attempts to increase blood supply with commercial incentives have raised ethical concerns, and current proposed artificial blood substitutes are unable to fully replicate the function of native red blood cells (RBCs). In this study, we explore the potential strategy of alleviating blood shortages through enzymatic conversion of A, B, and AB blood types to blood type O. In theory, this process eliminates ABO patient-donor incompatibility, which increases the supply of universal donor blood. Three glycoside hydrolases, -N-acetylgalactosaminidase, -galactosidase, and endo-{beta}-galactosidase, were selected to act as molecular scissors to cleave terminal residues on A and B RBC surface antigens and catalyze the conversion process. These enzymes were recombinantly expressed in BL21(DE3) Escherichia coli and purified through nickel ion affinity chromatography. A combination of colorimetric substrate assays, thin-layer chromatography, and mass spectroscopy were utilized to evaluate enzyme functionality. Enzyme efficiency was modeled using Michaelis-Menten kinetics. Partial enzymatic A-to-O blood type conversion on porcine red blood cells was observed with slide agglutination tests. Results confirm recombinant enzyme-mediated blood type conversion as a potential strategy for alleviating blood shortages.

biochemistry↗

bioRxiv2021

Identification of Immunodominant T-lymphocyte Epitope Peptides in HPV 1, 2 and 3 L1 Protein for Novel Cutaneous Wart Vaccine

BackgroundCommon warts and flat warts are caused by the human papillomavirus (HPV). Peak incidence of wart infection occurs in schoolchildren aged 12-16, where prevalence can be as high as 20%. Traditional treatments aimed at destruction of wart tissue have low clearance rates and high recurrence rates. Occasional reports have even shown warts becoming malignant and progressing into verrucous carcinoma. Current licensed HPV vaccines largely target higher-risk oncogenic HPV types, but do not provide coverage of low-risk types associated with warts. To date, little attention has been given to the development of effective, anti-viral wart treatments. ObjectiveThis study aims to identify immunodominant T-lymphocyte epitopes from the L1 major capsid protein of HPV 1, 2 and 3, a foundational step in bioengineering a peptide-based vaccine for warts. MethodsCytotoxic T-cell and helper T-cell epitopes were predicted using an array of immunoinformatic tools against a reference panel of frequently observed MHC-I and MHC-II alleles. Predicted peptides were ranked based on IC50 and IFN-{gamma} Inducer Scores, respectively, and top performing epitopes were synthesized and subjected to in vitro screening by IFN-{gamma} enzyme-linked immunosorbent spot assay (ELISpot). Independent trials were conducted using PBMCs of healthy volunteers. Final chosen peptides were fused with flexible GS linkers in silico to design a novel polypeptide vaccine. ResultsSeven immunodominant peptides screened from 44 predicted peptides were included in the vaccine design, selected to elicit specific immune responses across MHC class I and class II, and across HPV types. Evaluation of the vaccines properties suggest that the vaccine is stable, non-allergenic, and provides near complete global population coverage (>99%). Solubility prediction and rare codon analysis indicate that the DNA sequence encoding the vaccine is suitable for high level expression in Escherichia coli. ConclusionsIn sum, this study demonstrates the potential and lays the framework for the development of a peptide-based vaccine against warts.

immunology↗

bioRxiv2021

The Effects of Phenolic Compounds Isolated from Chinese Herbal Medicine Rhodiola Rosea on Preventing Photoaging of Keratinocytes

Among the many health benefits Chinese herbal medicine (CHM) presents, anti-aging is of special interest (Shen, Jiang, Yang, Wang, & Zhu, 2017; Zhao & Luo, 2017). Reported to possess anti-aging effects, the CHM Rhodiola rosea L., known colloquially as the "golden root", has been widely incorporated in various drinks, daily supplements, and even cosmetics. This study investigates the effects of commercial R. rosea extracts and natural R. rosea roots on preventing UV-induced photoaging of the skin and correlates such effects with the composition of active ingredients in the extracts. To simulate the photoaging process, drug treated HaCaT cells were exposed to UVA and UVB radiation. The pharmacological anti-aging effects of R. rosea extracts were evaluated qualitatively and quantitatively through confocal immunofluorescence images with {gamma}-H2A.X marker and telomerase activity assay (Telo TAGGG Telomerase PCR-ELISA). Preparatory thin layer chromatography and high-performance liquid chromatography were performed to isolate and quantify active ingredients. Cultured HaCaT cells showed morphological change after exposure to both UVA (>15.0 J) and UVB (>2000 mJ). The photoaging of keratinocytes was rescued by pretreating cells with R. rosea extracts as well as salidroside and rosavin active ingredients (P < 0.05). R. rosea-treated cells were characterized by increased telomerase activity and fewer {gamma}-H2A.X foci compared to that of the control. Extracts with better preventative effects contained higher salidroside and rosavin content. The findings in this study reaffirm R. roseas efficacy as an anti-aging remedy and provide a basis for CHMs integration into the mainstream of global healthcare.

biochemistry↗