Ultracentrifugation (UC) has long been considered the "gold standard" for extracellular vesicle (EV) isolation. However, due to its drawbacks such as high cost of an ultracentrifuge and rotors, time-c Show more
Ultracentrifugation (UC) has long been considered the "gold standard" for extracellular vesicle (EV) isolation. However, due to its drawbacks such as high cost of an ultracentrifuge and rotors, time-consuming and labor-intensive protocol, low yield considering initial biofluid volume and low throughput, development of new EV isolation approaches is still ongoing. Here we compare three methods for isolating the most studied EV subtype, small extracellular vesicles (sEVs), from human plasma: ultracentrifugation (UC), express asymmetric depth filtration (ExADFi), and anti-CD9 immunoaffinity capture (AS-CD9) with focus on their Raman and proteomic profiles. For all three methods, purity and quality of the sEV isolation were assessed based on the level of contamination of the sEV fraction with major plasma proteins such as albumin and apolipoproteins (APOA1, APOH, APOA4, APOC2, APOC1, and APOC4). UC showed the highest ratio of protein to nanoparticle concentration. AS-CD9 and ExADFi provided comparable to UC purity and levels of non-vesicular contaminants with AS-CD9 requiring minimal time and labor. ExADFi showed characteristics including purity of the sEV samples, yield, and isolation time that is between the UC and AS-CD9 methods. Raman spectroscopy provided more details about characteristics of the isolated sEVs and confirmed differences observed in the proteomic profiles. The findings demonstrate that the AS-CD9 and ExADFi methods could be appropriate substitutes of the classical UC-based isolation method and be chosen depending on the final requirements and use of the purified sEVs such as further functional and biomarker studies. Show less
Although it is well known that chromosomes are non-randomly organized during interphase, it is not completely clear whether higher-order chromatin structure is transmitted from mother to daughter cell Show more
Although it is well known that chromosomes are non-randomly organized during interphase, it is not completely clear whether higher-order chromatin structure is transmitted from mother to daughter cells. Therefore, we addressed the question of how chromatin is rearranged during interphase and whether heterochromatin pattern is transmitted after mitosis. We additionally tested the similarity of chromatin arrangement in sister interphase nuclei. We noticed a very active cell rotation during interphase, especially when histone hyperacetylation was induced or transcription was inhibited. This natural phenomenon can influence the analysis of nuclear arrangement. Using photoconversion of Dendra2-tagged core histone H4 we showed that the distribution of chromatin in daughter interphase nuclei differed from that in mother cells. Similarly, the nuclear distribution of heterochromatin protein 1β (HP1β) was not completely identical in mother and daughter cells. However, identity between mother and daughter cells was in many cases evidenced by nucleolar composition. Moreover, morphology of nucleoli, HP1β protein, Cajal bodies, chromosome territories, and gene transcripts were identical in sister cell nuclei. We conclude that the arrangement of interphase chromatin is not transmitted through mitosis, but the nuclear pattern is identical in naturally synchronized sister cells. It is also necessary to take into account the possibility that cell rotation and the degree of chromatin condensation during functionally specific cell cycle phases might influence our view of nuclear architecture. Show less