Posters

Cells release extracellular vesicles (EVs) of different sizes and intracellular origin. Due to their heterogenicity, the isolation of the target EV population from a mixture of supernatant-derived particles can be challenging. Anion exchange chromatography (AEX) exploits the negative charge on EV surface molecules for binding to the positively charged solid phase. CIMmultus® EV, an AEX chromatography monolith column, can separate EVs in subpopulations based on charge and offers insight into the heterogenicity of particles. Besides the availability of preparative tools for separation, combining multiple orthogonal and complementary characterization tools is crucial for defining the EV product of interest. In this work, we used a multiple-detector PATfix® system for the analysis of CIMmultus EV-fractionated samples. Samples were analyzed for the presence of EV-related tetraspanins using the fluorescence detector. PATfix MALS 3609 detector was used for the analysis of particle-containing samples and calculation of particle sizes.

New development in the modern biotechnology increased the need for plasmid DNA (pDNA) with sizes above 10 kbp (large pDNA), but their chromatographic purification is often challenging due to low process yields and column clogging. There are 
indirect proofs that open circular (OC) pDNA isoform is the main troublemaker due to its physical entrapment within the narrow channels of chromatographic media. Increasing the channel size of chromatographic support should decrease the negative 
impact and improve the chromatographic performance. The aim of the study was to use novel Convective Interaction Media® (CIM®) monolith chromatographic columns with large, 6 µm channels, for analytical and preparative separation of pDNA. The effect of supercoiled (SC), OC and linear (LIN) pDNA isoforms on chromatographic performance was thoroughly evaluated.

Sample displacement chromatography (SDC) is a chromatographic technique that utilizes differences in relative binding affinities of components in a sample mixture under chromatographic conditions. Here, we use SDC approach with CIM® C4 HLD monoliths under hydrophobic interaction chromatography (HIC) conditions to separate plasmid DNA (pDNA) isoforms under overloading conditions, where supercoiled (SC) isoform acts as a displacer of open circular (OC) or linear isoform. High purity of SC isoform is beneficial for use of plasmids as vaccines, transfecting agents for production of gene therapy viral vectors, or as starting material for linearization prior to IVT reaction in production of mRNA vaccines.

Agarose gel electrophoresis (AGE) analysis is an important method for monitoring of plasmid DNA (pDNA) quality, with ability to separate pDNA isoforms (sc, oc, lin, multimer). Plasmid linearization can be monitored for purposes of producing starting material for mRNA production. Electrophoretic conditions and, more importantly, matrix used for sample dilution before gel loading can affect analytical results. We have observed that purified linear pDNA shows an additional band in AGE analysis of the sample in water medium, which can lead to misinterpretation of results. 

Extracellular vesicles (EV) are lipid bound products secreted by cells. Among them, exosomes have great potential for clinical applications. Animal and human-derived components used in cell culture, such as fetal bovine serum (FBS), naturally contain exosomes that can cross-contaminate the desired product. In order to study exosomes derived from cells of interest, multiple producers have come up with exosome-depleted FBS (EV (-) FBS) generated using different approaches. In this work we evaluated commercially available EV (-) FBS supplements for residual exosome content and tested their performance in upstream exosome production process. The analysis was performed with PATfix high pressure liquid chromatography system using PATfix size exclusion (SEC) analytical method.

Optimizing processing steps in sc pDNA isolation is critical for obtaining good process yields as well as high product purity. PATfix platform with convective chromatography media (e.g. monolith) offers a rapid analytical method to characterize complex biomolecular mixtures and gives immediate feedback during process development. E coli lysis represents such a challenging step, where multiple critical quality attributes need to be identified and critical processing parameters optimized. This approach leads to better yields and product purity, allowing for simplified downstream steps. A new PATfix analytical platform presented here uses CIMac pDNA column, to separate and characterize plasmid from impurities, allowing for easy optimization of key parameters such as RNA removal.

Removal of host cell DNA is essential for all human-injectable biologics. This poster shows a method for achieving low host cell levels in preparations of exosomes. Purified exosome samples were prepared with anion exchange chromatography (AEC) and pre-treated with tangetial flow filtration (TFF) and nuclease treatment. Results are compared with an experimental control using TFF and size exclusion chromatohraphy (SEC).

The steps in purification process are illustrated by analytical size exclusion chromatography (SEC) on PATfix system with in-line UV, MALS and fluorescence detectors and by staining with Picogreen reagent. This technique visualizes sample composition by size, UV, light scattering and fluorescent properties.

Exosomes fulfill a critical role as communicators among cells, with targeting and message content depending on their surface receptors and payload. This makes them obvious candidates for an extensive range of diagnostic, therapeutic applications and a need for a fast, robust and scalable purification procedure.

CIMmultus™ monolithic columns are designed to meet the special fractionation needs of very large biologics like exosomes.

We show examples of exosome purification from cell culture with CORNERSTONE Exosome Process Development Pack and analysis of exosomal vesicle populations by Image stream flow cytometry.

This poster shows how Multi-Angle Light Scattering detector and Fluorescence detector couppled to PATfix analytical system can be used to track extracellular vesicles through purification process. Samples were analyzed by analytical size exclusion chromatography (SEC). On SEC cell culture components diffuze into pores of chromatographic media and are separated (mostly) based on size. Particles larger than the media pore size are excluded in the void peak. This peak represents extracellular vesicles including apoptosomes, microvesicles and exosomes as well as cell debris and aggregates.

CIM® chromatographic monoliths enable high 1) productivity of pDNA downstream process (DSP) due to high dynamic binding capacity for pDNA in small elution volumes and short chromatographic runs; 2) high resolution power due to convective-based mass transfer.

Sample displacement mode utilizes different relative binding affinities of components in a sample mixture and separates pDNA isoforms under overloading conditions - where sc pDNA isoform acts as a displacer of oc or linear pDNA isoform.

Preparative scale chromatographic separation of open-circular (oc) from supercoiled (sc) plasmid DNA (pDNA) isoforms has been already established on CIM® C4 with high ligand density (C4 HLD) monolithic columns with sample loading in 3.0 M ammonium sulphate (AS). The process requires high molarity of AS, increasing the overall cost of the process. Sample displacement chromatography (SDC) can be used as an alternative to decrease the AS concentration required during loading onto hydrophobic chromatographic supports. This study compares three chromatographic monoliths with different hydrophobic ligands on the surface (C4 HLD, pyridine and histamine) for the purification of different pDNA vectors in SD mode.

Since plasmid DNA (pDNA) as a pharmaceutical product has stringent requirements of purity and efficacy, one or more chromatographic steps are often used in the downstream processing train. High ligand density butyl-modified (C4 HLD) monolithic support is currently used in a polishing step of a pDNA purification process (1) and is mainly focused to supercoiled (sc) pDNA isoform separation from the open circular (oc) and linear pDNA isoform as well as for removal of remaining gDNA and RNA. The goal of the study was to compare the productivities of two variations of the polishing chromatographic process employing monoliths – classical bind-elute (BE) versus recently described (2) sample displacement purification (SDP). Classical purification requires high concentration of ammonium sulphate (AS) during loading step and elution is then achieved by descending AS gradient. SDP utilises different relative binding affinities of components in a sample mixture and separates pDNA isoforms under overloading conditions, where sc pDNA isoform acts as a displacer of oc or linear pDNA isoform.

Exosomes are nano-sized vesicles that are released by many different cell types. They are involved in the transport of a wide range of signalling molecules, including mRNA, microRNA and proteins. Exosomes have been found into body fluids and multiple roles have been ascribed to exosomes, in particular in cell signalling where it has been demonstrated their correlation to disease progression and their overexpression as specific tumour cell biomarkers, suggesting their important role in their diagnosis.

This initial screening oriented towards the separation of exosomes from a cell culture supernatant, has been developed by BIA Separations in collaboration with Exosomics Siena. Exosomes used for this study were cultivated in two different cell lines, MeWo and LNCap, and, after the harvesting, a relatively pure target molecule was obtained after several centrifugations, filtrations and batch affinity capture step with a commercial purification kit. In order to speed-up the process and bring current DSP on a higher level, a novel purification approach based on chromatography, using CIM® monolithic columns was investigated. Monolithic supports represent a new generation of chromatographic media. Due to their large inner channel diameters and enhanced mass transfer characteristics, methacrylate monoliths offer efficient and fast separation of large biomolecules like vescicles, pDNA, viruses and monoclonal antibodies. High binding capacity, good product recovery and resolution are also benefits of monoliths. Different samples, (Standard batch purified exosomes, Culture supernatant filtered, Culture supernatant non-filtered), derived from MeWo and LNCap culture media,, were screened. QA, SO3, DEAE and OH CIM 1mL tube - 6μm pore size were screened. CIM® QA - 6μm pores was chosen.

One of the major requirements for pharmaceutical-grade pDNA is its high homogeneity, being mostly in supercoiled (sc) isoform. Chromatographic separation of sc pDNA from open coiled (oc) or linear isoform is challenging due to their similar interactions with the chromatographic phases. Promising separation efficiency of pDNA isoforms was proven on recently developed histamine modified monolithic chromatographic column in descending ammonium sulfate gradient. The aim of the study was to further optimise the chromatographic conditions for sample analysis, where all three isoforms would be baseline separated.

Monolith chromatography media coupled with metal affinity ligands proved superior to the conventional particle-based matrix as a plasmid DNA (pDNA) purification platform. By harnessing the differential affinity of pDNA, RNA. Host cell proteins and endotoxin to copper ions in the solution a majority of endotoxin (90%) was removed from the alkaline cell lysate using CuCl2-induced precipitation. RNA and remaining endotoxin were subsequently processed by copper immobilized metal affinity column employing either monolith or particle-based matrix where both RNA and endotoxin were removed below detection limit with almost complete recovery of pDNA in the monolith was found to have several advantages in terms of handling feedstocks crowded with RNA in a concentration-independent manner and exhibiting flowrate-independent dynamic binding capacity for RNA. This enabled monolith-based process to be conducted at high feed concentration and flow rate. Resulting in pDNA vaccine purification at a high yield and purity and the process conditions investigated, the use of monolith column gave at least three fold higher productivity for recovery of purified pDNA as compared to the particle- based column, demonstrating its potential as a more rapid and economical platform for pDNA vaccine purification.

The present study describes a new methodology to quantify and monitor the quality of supercoiled (sc) plasmid DHA (pDLIA), using a monolithic column based on anion-exchange chromatography. This analytical method with UV detection allows distinguishing the plasmid isoforms by a NaCl stepwise gradient. The selectivity, Linearity, accuracy, reproducibility and repeatability of the method have been evaluated, and the lower quantification and detection limits were also established. The validation was performed according to the guidelines, being demonstrated that the method is precise and accurate for a sc plasmid concentration up to 200 µg/mL. The main advance achieved by using this monolithic method is the possibility to quantify the sc plasmid in a sample containing other plasmid topologies, in a 4 minutes experiment. This work also intends to evaluate the possibility to assess the sc pDNA present in more complex samples, allowing the control of the samples recovered from different bioprocess steps.

Application of plasmid DNA for gene therapy and vaccination has gained huge interest in last two decades. Topological homogeneity and impurity content are crucial for therapeutic usage of pDNA. Major influence on achieving regulatory demands in pDNA production has downstream processing and in order to get optimal purity different purification techniques have to be included. It was demonstrated that methacrylate monoliths can be used for efficient purification process of plasmid DNA. High dynamic binding capacities and high flow rates of methacrylate monolith enabled excelent purity and productivity.

Application of plasmid DNA for gene therapy and vaccination has gained substantial interest in the last two decades. Topological homogeneity and impurity content are crucial for therapeutic usage of pDNA. Downstream processing has major influence on achieving regulatory demands in pDNA production and in order to get optimal purity different purification techniques have to be applied. It was demonstrated that methacrylate monoliths can be used for efficient purification process of plasmid DNA. High dynamic binding capacities and high flow rates of methacrylate monolith enable excellent purity and productivity.

Anion-exchange chromatography is fundamental in downstream processing of plasmids both as a process and analytical technique. CIM anion-exchange monolithic columns have already been successfully used for the industrial scale purification of pharmaceutical grade small plasmid DNA [1].

In this work we report about the use of the newly developed monolithic analytical column intended for plasmid DNA determination in terms of its analytical performance. Higher degree of sensitivity, precision and accuracy is necessary in order to determine the quality of clinical grade DNA intended for therapeutic use. Plasmids purified from Escherichia coli fermentation exist predominantly in the supercoiled form (SC) the other two topoisomers present in the final product are mostly the open circular (OC) and linear forms [2]. Different chromatographic conditions were tested and the separation was optimized in terms of buffer and pH selection as well as in terms of gradient slope and column length. The results were compared to the results obtained with established analytical methods.

Gene therapy has already shown some great results in treatment and cure of some monogene diseases, such as diabetes. While the use of genetically modified viruses raises safety concerns, synthetic formulations of genes inserted in plasmids are regarded as safer. At present, most clinical trials involve plasmids smaller than 10 kb. However, the concern that regulation of the functioning of the gene is ensured together with the expectation of the progression of gene therapy to multigene disfunctions, like cancer or complex nevrodegenerative disfunctions (Alzheimer disease), will require the production of larger plasmids [1].