Lidija Filipović - Secondment from UBFC to VHIR

As part of the EXPAND-EV project, Lidija Filipovic spent a month at the Vall d’Hebron Institute of Research (VHIR), where she had the opportunity to work on engineering cell lines to produce fluorescent extracellular vesicles (EVs). The main focus was to optimize an immunoaffinity-based purification method and test how well it performs across different types of cell lines. She also compared this method to size-exclusion chromatography (SEC), which is more commonly used.

One of the key ideas behind this secondment was to establish the most efficient and reproducible EV purification workflow that could be shared across the entire consortium, allowing everyone to follow the same protocol and get consistent results.

During her time there, Lidija learned how to grow cancer cell lines under FBS-free conditions and collect conditioned media for EV isolation. She used a combination of fluorescence microscopy, confocal microscopy, and flow cytometry to check transfection efficiency and confirm that the constructs were being expressed properly and that fluorescent EVs were being released.

After collecting the media, she processed it using tangential flow filtration (TFF) to remove larger particles and concentrated it with AMICON filters. She then split the samples to compare the SEC method with the immunoaffinity-based approach. At the same time, she also worked on producing a nanobody that targets the ALFA-tag, using E. coli and IPTG induction to express the protein.

This experience helped her build on her existing knowledge of EVs and protein purification. It was especially valuable to work hands-on with different techniques and see how fluorescent labeling can simplify optimization and analysis.