Table 2.
Comparison of three forms of liquid biopsies, including sEVs, ctDNA, and CTC.
| sEVs | ctDNA | CTC | |
|---|---|---|---|
| Origination | Liver tumor cells | Dying tumor cells | Live solid tumor |
| Required sample volume | ≤1 ml plasma | 5–10 ml blood | 5–60 ml blood |
| Sample storage | Plasma: −80 °C for years | Whole blood: ≤96 h | Whole blood: ≤96 h, a few hours for viable cells |
| Counting & DNA amount | 108-1011/ml plasma; 5–200 ng/ml plasma | 10–400 ng/ml plasma | 1-100 cells/7.5 ml blood; ~10 pg/cell |
| Integrity of DNA | Medium: >10k bp [343] | Low: 100–300 bp [375,376] | High: intact DNA |
| DNA analysis | Yes | Yes | Yes |
| RNA analysis | Yes | No | Yes |
| Proteomics analysis | Yes | No | Yes, but not at single cell level |
| Lipidomic analysis | Yes | No | Yes, but not at single cell level |
| FDA approved assays | Not available | Available | Available |