Identification of Surfactant Impact on a Monoclonal Antibody Characterization via HPLC-Separation Based and Biophysical Methods.

PURPOSE OR OBJECTIVE: Surfactants, including polysorbates and poloxamers, play a crucial role in the formulation of therapeutic proteins by acting as solubilizing and stabilizing agents. They help prevent protein aggregation and adsorption, thereby enhancing the stability of drug substance and products., However, it is important to note that utilizing high concentrations of surfactants in protein formulations can present significant analytical challenges, which can ultimately affect the product characterization. METHODS: In our study, we specifically investigated the impact of elevated surfactant concentrations on the characterization of monoclonal antibodies. We employed various analytical techniques including size-exclusion chromatography (SEC), capillary electrophoresis (CE-SDS), a cell based functional assay, and biophysical characterization. RESULTS: The findings of our study indicate that higher levels of Polysorbate 80 (PS-80) have adverse effects on the measured purity, biological activity, and biophysical characterization of biologic samples. Specifically, the elevated levels of PS-80 cause analytical interferences, which can significantly impact the accuracy and reliability of analytical studies. CONCLUSIONS: Our study results highlight a significant risk in analytical investigations, especially in studies involving the isolation and characterization of impurities. It is important to be cautious of surfactant concentrations, as they can become more concentrated during common sample manipulations like buffer exchange. Indeed, the research presented in this work emphasizes the necessity to evaluate the impact on analytical assays when there are substantial alternations in the matrix composition. By doing so, valuable insights can be gained regarding potential challenges associated with assay development and characterization of biologics with complex formulations.

Colocalization of protein and microRNA markers reveals unique extracellular vesicle subpopulations for early cancer detection.

Extracellular vesicles (EVs) play important roles in cell-cell communication but are highly heterogeneous, and each vesicle has dimensions smaller than 200 nm with very limited amounts of cargos encapsulated. The technique of NanOstirBar (NOB)-EnabLed Single Particle Analysis (NOBEL-SPA) reported in the present work permits rapid inspection of single EV with high confidence by confocal fluorescence microscopy, thus enables colocalization assessment for selected protein and microRNA (miRNA) markers in the EVs produced by various cell lines, or present in clinical sera samples. EV subpopulations marked by the colocalization of unique protein and miRNA combinations were discovered to be able to detect early-stage (stage I or II) breast cancer (BC). NOBEL-SPA can be adapted to analyze other types of cargo molecules or other small submicron biological particles. Study of the sorting of specific cargos to heterogeneous vesicles under different physiological conditions can help discover distinct vesicle subpopulations valuable in clinical examination and therapeutics development and gain better understanding of their biogenesis.

Colocalization of Protein and microRNA Markers Reveals Unique Extracellular Vesicle Sub-Populations for Early Cancer Detection.

Extracellular vesicles (EVs) play important roles in cell-cell communication but they are highly heterogeneous, and each vesicle has dimensions smaller than 200 nm thus encapsulates very limited amounts of cargos. We report the technique of NanOstirBar (NOB)-EnabLed Single Particle Analysis (NOBEL-SPA) that utilizes NOBs, which are superparamagnetic nanorods easily handled by a magnet or a rotating magnetic field, to act as isolated "islands" for EV immobilization and cargo confinement. NOBEL-SPA permits rapid inspection of single EV with high confidence by confocal fluorescence microscopy, and can assess the colocalization of selected protein/microRNA (miRNA) pairs in the EVs produced by various cell lines or present in clinical sera samples. Specific EV sub-populations marked by the colocalization of unique protein and miRNA combinations have been revealed by the present work, which can differentiate the EVs by their cells or origin, as well as to detect early-stage breast cancer (BC). We believe NOBEL-SPA can be expanded to analyze the co-localization of other types of cargo molecules, and will be a powerful tool to study EV cargo loading and functions under different physiological conditions, and help discover distinct EV subgroups valuable in clinical examination and therapeutics development.

Cancer-cell-secreted extracellular vesicles suppress insulin secretion through miR-122 to impair systemic glucose homeostasis and contribute to tumour growth.

Epidemiological studies demonstrate an association between breast cancer (BC) and systemic dysregulation of glucose metabolism. However, how BC influences glucose homeostasis remains unknown. We show that BC-derived extracellular vesicles (EVs) suppress pancreatic insulin secretion to impair glucose homeostasis. EV-encapsulated miR-122 targets PKM in ß-cells to suppress glycolysis and ATP-dependent insulin exocytosis. Mice receiving high-miR-122 EVs or bearing BC tumours exhibit suppressed insulin secretion, enhanced endogenous glucose production, impaired glucose tolerance and fasting hyperglycaemia. These effects contribute to tumour growth and are abolished by inhibiting EV secretion or miR-122, restoring PKM in ß-cells or supplementing insulin. Compared with non-cancer controls, patients with BC have higher levels of circulating EV-encapsulated miR-122 and fasting glucose concentrations but lower fasting insulin; miR-122 levels are positively associated with glucose and negatively associated with insulin. Therefore, EV-mediated impairment of whole-body glycaemic control may contribute to tumour progression and incidence of type 2 diabetes in some patients with BC.

Calibration-free analysis of surface proteins on single extracellular vesicles enabled by DNA nanostructure.

Extracellular vesicles (EVs) are essential intercellular communicators that are of increasing interest as diagnostic biomarkers. Exploring their biological functions and clinical values, however, remains challenging due to their small sizes and high heterogeneity. Herein, we report an ultrasensitive method that employs target-initiated construction of DNA nanostructure to detect single EVs with an input as low as 100 vesicles/µL. Taking advantage of both DNA nanostructure labeling and EV membrane staining, the method can also permit calibration-free analysis of the protein profiles among different EV samples, leading to clear EV differentiation by their cell of origin. Moreover, this method allows co-localization of dual protein markers on the same EV, and the increased number of EVs carrying dual tumor proteins present in human serum could differentiate cancer patients at the early developmental stage from healthy controls. Our results demonstrate the great potential of this single-EV visualization method in non-invasive detection of the EV-based protein biomarkers for cancer diagnosis and treatment monitoring.

Physical and chemical template-blocking strategies in the exponential amplification reaction of circulating microRNAs.

The detection of circulating miRNA through isothermal amplification wields many attractive advantages over traditional methods, such as reverse transcription RT-qPCR. However, it is challenging to control the background signal produced in the absence of target, which severely hampers applications of such methods for detecting low abundance targets in complex biological samples. In the present work, we employed both the cobalt oxyhydroxide (CoOOH) nanoflakes and the chemical modification of hexanediol to block non-specific template elongation in exponential amplification reaction (EXPAR). Adsorption by the CoOOH nanoflakes and the hexanediol modification at the 3' end effectively prevented no-target polymerization on the template itself and thus greatly improved the performance of EXPAR, detecting as low as 10 aM of several miRNA targets, including miR-16, miR-21, and miR-122, with the fluorescent DNA staining dye of SYBR Gold™. Little to no cross-reactivity was observed from the interfering strands present in 10-fold excess. Besides contributing to background reduction, the CoOOH nanoflakes strongly adsorbed nucleic acids and isolated them from a complex sample matrix, thus permitting successful detection of the target miRNA in the serum. We expect that simple but sensitive template-blocking EXPAR could be a valuable tool to help with the discovery and validation of miRNA markers in biospecimens. Graphical abstract.

Analysis of circulating non-coding RNAs in a non-invasive and cost-effective manner.

Non-coding RNAs (ncRNAs) participate in regulation of gene expression, and are highly relevant to pathological development. They are found to be stably present in diverse body fluids, including those in the circulatory system, which can be sampled non-invasively for clinical tests. Thus, circulating ncRNAs have great potential to be disease biomarkers. However, tremendous efforts are desired to discover and utilize ncRNAs as biomarkers in clinical diagnosis, calling for technological advancement in analysis of circulating ncRNAs in biospecimens. Hence, this review summarizes the recent developments in this area, highlighting the works devoted to cancer diagnosis and prognosis. Three main directions are focused: 1) Extraction and purification of ncRNAs from body fluids; 2) Quantification of the purified circulating ncRNAs; and 3) Microfluidic platforms for integration of both steps to enable point-of-care diagnostics. These technologies have laid a solid foundation to move forward the applications of circulating ncRNAs in disease diagnosis and cure.

A Single Extracellular Vesicle (EV) Flow Cytometry Approach to Reveal EV Heterogeneity.

Extracellular vesicles (EVs) actively participate in intercellular communication and pathological processes. Studying the molecular signatures of EVs is key to reveal their biological functions and clinical values, which, however, is greatly hindered by their sub-100 nm dimensions, the low quantities of biomolecules each EV carries, and the large population heterogeneity. Now, single-EV flow cytometry analysis is introduced to realize single EV counting and phenotyping in a conventional flow cytometer for the first time, enabled by target-initiated engineering (TIE) of DNA nanostructures on each EV. By illuminating multiple markers on single EVs, statistically significant differences are revealed among the molecular signatures of EVs originating from several breast cancer cell lines, and the cancer cell-derived EVs among the heterogeneous EV populations are successfully recognized. Thus, our approach holds great potential for various biological and biomedical applications.