Liquid Biomarker Flashcards
what is a liquid biopsy
Sampling and analysis of non-solid biological tissue, primarily blood. It is a minimally invasive technology for detection Of molecular biomarkers. Representative Of the tissue/s from which it has spread.
examples of liquids used for liquid biopsy (6 points)
blood, plasma, CSF, urine, amniotic fluid, saliva
Types of material we can find circulating in blood (7 points )
Circulating endothelial cells (CEC), Extracellular micro-vesicle (exosomes), metabolites, disseminated tumour cells (DTCs),cell free nucleotide, tumour educated platelets (TEPs), circulating tumour cells (CTCs)
what are the 2 types of tube used in liquid biopsy
EDTA,citrate
cell-free DNA tubes
properties of EDTA, citrate tubes
contain anticoagulant to prevent clotting
Logistics and storage of EDTA, citrate
Onsite centrifugation within six hours of collection to isolate plasma and avoid white cell apoptosis. if not possible sample can be stored at 4 degrees Celsius for up to a week
Properties of cell free DNA tubes
Contain a stabiliser to prevent release of gDNA from white blood and haemolysis of red blood cells
Logistics and storage of cell free DNA tube
Samples can be stored for 6-14 days at 6-37 degree Celsius
speed, time and temperature at which you centrifuge for liquid biopsies
15 minutes
2000 xg
4 degrees Celsius
order of content from top to bottom after centrifugation for liquid biopsies and percentages of each content
Plasma 55%
less than 1% buffy coat
45% haematocrit
Which content contains cfDNA and exosomes
plasma
which content contains WBC and CTCs
buffy coat
which content contains RBC
Haematocrit
what are circulating tumour cells (CTC)
- Cells that have detached from a tumour and travel through the bloodstream
to other parts Of the body- single cells or clusters. - Marker for tumour growth and negative cancer prognosis and treatment
response.
why can we isolate tumour cells
We can isolate circulating tumour cells because they are CD45 negative EpCAM positive And CK a positive