Affiliations: [a] Center for Theoretical and Applied Neuro-Oncology, University of California, San Diego, CA, USA | [b] Department of Neurosurgery, University of California, Los Angeles, CA, USA | [c] Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China
Correspondence:
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Corresponding author: Clark C. Chen, Center for Theoretical and Applied Neuro-Oncology, University of California, San Diego, CA, USA. Tel.: +1 858 246 0674; Fax: +1 858 534 8899; E-mail:clarkchen@ucsd.edu
Note: [1] These authors shared responsibility as senior authors.
Abstract: BACKGROUND: Tumor specific genetic material can be detected in
extracellular vesicles (EVs) isolated from blood, cerebrospinal fluid (CSF),
and other biofluids of glioblastoma patients. As such, EVs have emerged as a
promising platform for biomarker discovery. However, the optimal procedure
to transport clinical EV samples remains poorly characterized. METHODS: We examined the stability of EVs isolated from CSF of
glioblastoma patients that were stored under different conditions. EV
recovery was determined by Nanoparticle tracking analysis, and qRT-PCR was
performed to determine the levels of miRNAs. RESULTS: CSF EVs that were lyophilized and stored at room
temperature (RT) for seven days exhibited a 37-43% reduction in EV
number. This reduction was further associated with decreased abundance of
representative miRNAs. In contrast, the EV number and morphology remained
largely unchanged if CSF were stored at RT. Total RNA and representative
miRNA levels were well-preserved under this condition for up to seven days.
A single cycle of freezing and thawing did not significantly alter EV
number, morphology, RNA content, or miRNA levels. However, incremental
decreases in these parameters were observed after two cycles of freezing and
thawing. CONCLUSIONS: These results suggest that EVs in CSF are stable at RT
for at least seven days. Repeated cycles of freezing/thawing should be
avoided to minimize experimental artifacts.
