Imaging of Light-Enhanced Extracellular Vesicle-Mediated Delivery of Oxaliplatin to Colorectal Cancer Cells via Laser Ablation, Inductively Coupled Plasma Mass Spectrometry

Extracellular vesicles (EVs) are lipid bilayer structures released by all cells that mediate cell-to-cell communication via the transfer of bioactive cargo. Because of the natural origin of EVs, their efficient uptake by recipient cells, capacity to stabilize and transport biomolecules and their potential for cell/tissue targeting and preferential uptake by cancer cells, they have enormous potential for bioengineering into improved and targeted drug delivery systems. In this work, we investigated the use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) as a tool to measure the loading of platinum-based chemotherapeutic agents. The EV loading of oxaliplatin via co-incubation was demonstrated, and LA-ICP-MS imaging showed greater efficiency of delivery to colorectal cancer cells compared to free oxaliplatin, leading to enhanced cytotoxic effect. Further, the impact of EV co-loading with a porphyrin (C5SHU, known as 'C5') photosensitizer on oxaliplatin delivery was assessed. Fluorescence analysis using nano-flow cytometry showed dose-dependent EV loading as well as a trend towards the loading of larger particles. Exposure of OXA-C5-EV-treated colorectal cancer cells to light indicated that delivery was enhanced by both light exposure and porphyrins, with a synergistic effect on cell viability observed between oxaliplatin, EVs and light exposure after the delivery of the co-loaded EVs. In summary, this work demonstrates the utility of LA-ICP-MS and mass spectrometry imaging in assessing the loading efficiency and cellular delivery of platinum-based therapeutics, which would also be suitable for agents containing other elements, confirms that EVs are more efficient at delivery compared to free drugs, and describes the use of light exposure in optimizing delivery and therapeutic effects of EV-mediated drug delivery both in combination and independently of porphyrin-based photosensitizers.

University student-led public engagement event: increasing audience diversity and impact in a non-science space

There is a wealth of innovation in microbiology outreach events globally, including in the setting where the public engagement is hosted. Previous data indicate an underrepresentation of marginalized ethnic groups attending UK science-based public engagement events. This project engaged our student cohort, encompassing a diverse range of ethnic groups, to create an integrated art and science event within an existing series of adult education evenings. The study's objectives were to increase the proportion of visitors from marginalized ethnic groups and to gain a greater understanding of the impact of the event on the visitors' reported science capital. The participants' demographics, links to our students and University, and detailed impact on participants' science capital of the event were determined through analysis of exit questionnaires. There was an increase in the proportion of marginalized ethnic group visitors compared to similar previous events. A higher proportion of visitors from marginalized ethnic groups had links with our students and University compared to white/white British visitors. Elements of the exit questionnaire were mapped to the science capital framework and participants' science capital was determined. Both ethnically marginalized participants and white/white British visitors showed an increase in science capital, specifically dimensions of science-related social capital and science-related cultural capital, after the event. In conclusion, our study suggests that a student-led blended art and science public engagement can increase the ethnic diversity of those attending and can contribute towards creating more inclusive public engagement events.

MALDI and Trace Metal Analysis in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) remains one of the most prevalent causes of blindness throughout the world. Key to prevention of AMD is furthering the understanding of its pathology. In recent years, both the proteins within the innate immune system and essential and non-essential metals have been implicated in the pathology of AMD. Herein, a multidisciplinary and multimodal methodology has been taken to further our understanding of the role of the innate immune proteins and the essential metals within mouse ocular tissue.

Quantitative Investigation of Terbinafine Hydrochloride Absorption into a Living Skin Equivalent Model by MALDI-MSI

The combination of microspotting of analytical and internal standards, matrix sublimation, and recently developed software for quantitative mass spectrometry imaging has been used to develop a high-resolution method for the determination of terbinafine hydrochloride in the epidermal region of a full thickness living skin equivalent model. A quantitative assessment of the effect of the addition of the penetration enhancer (dimethyl isosorbide (DMI)) to the delivery vehicle has also been performed, and data have been compared to those obtained from LC-MS/MS measurements of homogenates of isolated epidermal tissue. At 10% DMI, the levels of signal detected for the drug in the epidermis were 0.20 ± 0.072 mg/g tissue for QMSI and 0.28 ± 0.040 mg/g tissue for LC-MS/MS at 50% DMI 0.69 ± 0.23 mg/g tissue for QMSI and 0.66 ± 0.057 mg/g tissue for LC-MS/MS. Comparison of means and standard deviations indicates no significant difference between the values obtained by the two methods.

The metabolism of 4-bromoaniline in the bile-cannulated rat: application of ICPMS ((79/81)Br), HPLC-ICPMS & HPLC-oaTOFMS

1. An excretion balance study was performed following i.p. administration of 4-bromoaniline (50 mg kg⁻¹) to bile-cannulated rats, using bromine-detected (^79/81Br) ICPMS for quantification. Approximately 90% of the dose was recovered in urine (68.9 ± 3.6%) and bile (21.4 ± 1.4%) by 48 h post-administration.

2. HPLC-ICPMS (^79/81Br) was used to selectively detect and profile the major urinary and biliary-excreted metabolites and determined that the 0–12 h urine contained at least 21 brominated metabolites with 19 bromine-containing peaks observed in the 6–12 h bile samples.

3. The urinary and biliary metabolites were subsequently profiled using HPLC-oaTOFMS. By exploiting the distinctive bromine isotope pattern ca. 60 brominated metabolites were detected in the urine in negative electrospray ionisation (ESI) mode while bile contained ca. 21.

4. While a large number of bromine-containing metabolites were detected, the profiles were dominated by a few major components with the bulk of the 4-bromoaniline-related material in urine accounted for by 4-bromoanaline O-sulfate (∼75% of the total by ICPMS, 84% by TOFMS). In bile a hydroxylated N-acetyl compound was the major metabolite detected, forming some ∼65% of the 4-bromoaniline-related material by ICPMS (37% by TOFMS).

Structural basis for SH2D1A mutations in X-linked lymphoproliferative disease

X-linked lymphoproliferative disease (XLP) is a rare and severe immune deficiency, characterized by abnormal immune responses to the Epstein-Barr virus. Recently, the gene responsible for XLP, SH2D1A, has been identified and shown to code for a small cytoplasmic protein with an SH2 domain that interacts with SLAM and 2B4, two receptorial molecules involved in signal transduction in T and NK cells, respectively. A variety of SH2D1A gene mutations have been reported thus far in XLP males. Here we describe a single-strand conformation polymorphism assay for mutation analysis in XLP. Four novel patients with SH2D1A mutations are described. These mutants, and the others previously reported in the literature, have been included in a Registry (SH2D1Abase) that is fully accessible on the World Wide Web. A three-dimensional model of the SH2 domain of the SH2D1A protein has been developed, based on homology with other SH2 domains. The structural consequences of disease-causing SH2D1A mutations are discussed.

DNA CpG methylation inhibits binding of NF-kappa B proteins to the HIV-1 long terminal repeat cognate DNA motifs

The regulation of cellular or viral gene expression is directly influenced by the pattern of methylated cytosine residues localized in the DNA of enhancer/promoter sequences. The mechanism of transcriptional silencing has been explained on the basis of either an indirect model, in which densely methylated DNA is recognized by proteins that may displace crucial transcription factors, or a direct model, in which binding of a single transcription protein is prevented by the presence of a methylated CpG dinucleotide localized in a sensitive region of a DNA motif. In this study, we have determined that methylation of the core CpG dinucleotide located within the NF-kappa B repeated motifs of the human immunodeficiency virus type 1 (HIV-1) long terminal repeat can inhibit the binding of the NF-kappa B protein complex from crude nuclear extracts or from purified bovine spleen and specifically inhibit the binding of recombinant p50 protein. We have used the electrophoretic mobility shift assay (EMSA) and DNaseI footprinting analysis to demonstrate that binding of the NF-kappa B proteins to their cognate motifs can be inhibited via the direct model proposed for methylation-mediated inhibition of DNA-protein interaction.