Extracellular vesicle depletion and UGCG overexpression mitigate the cell density effect in HEK293 cell culture transfection.

"Declaration of interests The authors declare no competing interests."

"This research was supported by grant PID2022-139019OB-I00 (Plan General del Conocimiento, Ministerio de Ciencia e Innovación, Gobierno de España). The research group Enginyeria de Bioprocessos i Biocatàlisi Aplicada ENG4BIO is recognized as 2021 SGR 00143 by Departament de Recerca i Universitats de la Generalitat de Catalunya. The authors would like to thank Dr. Amine Kamen (McGill University, Montreal, Canada) for providing the HEK293SF-3F6 cells and Dr. Ernest Milián Gonzalez (VCN Biosciences, Sant Cugat, Spain) for his generous contribution with the adenoviral stocks and qPCR validations. Technical help from Marc García Trujillo is highly appreciated. Support from José Amable Bernabé from the Institute of Material Science of Barcelona (ICMAB-CSIC, Barcelona Spain) with particle tracking techniques and the help of Martí de Cabo and Dr. Meritxell Vendrell from the Microscopy Service from the Universitat Autònoma de Barcelona (Barcelona, Spain) in the performance of electron and confocal microscopy analysis are very much appreciated. The authors would also like to show their gratitude to Inmaculada Jorge and Jesús Vázquez for the proteomic identification carried out at Centro Nacional de Investigaciones Cardiovasculares (CNIC, Madrid, Spain)."