Biology subjects

Martel, R.

Publications and source records attributed to Martel, R..

3 recordsLinked to original sources

bioRxiv2026

Iterative Extracellular Vesicle Protein Co-Expression Biomarker Refinement for Preoperative Classification of Histopathological Growth Patterns in Colorectal Liver Metastasis Patients

Preoperative triage of colorectal liver metastases (CRCLM) by histopathological growth pattern (HGP)--angiogenesis-dependent desmoplastic (dHGP) and vessel co-opting replacement (rHGP)--could guide anti-angiogenic therapy, yet HGP scoring requires resected tissue. We present an extracellular vesicle (EV) inner and outer protein (EVPio) co-expression assay and iterative biomarker refinement for plasma-based HGP classification. We established a minimal, high-throughput plasma pre-processing workflow (low-speed centrifugation and 0.45 m filtration) with comparable EVPio assay performance to size-exclusion chromatography. We established an EV biomarker selection template with growing cohorts--feasibility (n = 3), pilot (n = 9), discovery (n = 67)--ranking candidate protein pairs by signal quality (SNR, CV), redundancy (inter-correlation/orthogonality), and HGP separation (effect size, significance, ROC). This process reduced an initial 19x18 capture/detection set to a focused 9x9 panel (81 co-expression pairs). In a 58-patient CRCLM subset (22 dHGP, 14 rHGP, 22 mixed), three pairs achieved high signal quality with significant differential expression across HGPs. A three-feature linear discriminant model yielded 75.9% cross-validated accuracy (AUC 0.77) for classifying pure dHGP vs. non-dHGP. The results show that co-expression signatures capture defining features of HGP biology while revealing heterogeneity. The proposed EV biomarker refinement template is generalizable and our results show that co-expression signatures capture defining features of HGP biology supporting efforts towards clinically actionable, HGP-driven therapeutic guidance.

bioengineering↗

bioRxiv2023

Effect of sample preprocessing and extraction methods on the physical and molecular profiles of extracellular vesicles

Extracellular vesicles (EVs) are nanometric lipid vesicles that shuttle cargo between cells. Their analysis could shed light on health and disease conditions, but EVs must first be preserved, extracted and often pre-concentrated. Here we firstly compare plasma preservation agents, and secondly, using both plasma and cell supernatant, four EV-extraction methods including (i) ultracen-trifugation (UC), (ii) size exclusion chromatography (SEC), (iii) centrifugal filtration (LoDF), and (iv) accousto-sorting (AcS). We benchmarked them by characterizing integrity, size-distribution, concentration, purity and the expression profiles for nine proteins of EVs, as well as overall throughput, time-to-result and cost. We found that the difference between EDTA and citrate anticoagulants vary with the extraction method. In our hands, ultracentrifugation produced a high yield of EVs with low contamination; SEC is low-cost, fast, and easy to implement, but the purity of EVs is lower; LoDF and AcS are both compatible with process automation, small volume requirement, and rapid processing times. When using plasma, the LoDF was susceptible to clogging and sample contamination, while the AcS featured high purity but a lower yield of extraction. Analysis of protein profiles suggest that extraction methods extract different sub-population of EVs. Our study highlights the strength and weakness of sample preprocessing methods, and the variability in concentration, purity, and EV expression profiles of the extracted EVs. Pre-analytical parameters such as collection or pre-processing protocols must be considered as part of the entire process in order to address EV diversity and their use as clinically actionable indicators.

bioengineering↗

bioRxiv2022

Extracellular Vesicle Antibody Microarray for Multiplexed Inner and Outer Protein Analysis

Proteins are found both outside and inside of extracellular vesicles (EVs) and govern the properties and functions of EVs, while also constituting a signature of the cell of origin and of biological function and disease. Outer proteins on EVs can be directly bound by antibodies to either enrich EVs, or probe the expression of a protein on EVs, including in a combinatorial manner. However, co-profiling of inner proteins remains challenging. Here, we present the high-throughput, multiplexed analysis of extracellular vesicle inner and outer proteins (EVPio). We describe the optimization of fixation and heat-induced protein epitope retrieval for EVs, along with oligo-barcoded antibodies and branched DNA signal amplification for sensitive, multiplexed and high-throughput assays. We captured 4 subpopulations of EVs from colorectal cancer cell lines HT29 and SW403 based on EpCAM, CD9, CD63 and CD81 expression, and quantified the co-expression of 8 outer (integrins and tetraspanins) and 4 inner (heat shock, endosomal and inner leaflet) proteins. The differences in co-expression patterns were consistent with the literature and known biological function. In conclusion, EVPio analysis can simultaneously detect multiple inner and outer proteins in EVs immobilized on a surface, opening the way to extensive combinatorial protein profiles for both discovery and clinical translation.

bioengineering↗