To assess intra individual biological variability of serum cartilage specific biomarker Coll2-1 and define the best standardized conditions for blood sampling in clinical trials.
Blood samples were taken from 116 subjects with diagnosed knee osteoarthritis (OA) at a single timepoint as well as from 15 healthy subjects under various conditions, including fasting condition, sampling time, sampling season, physical activity, blood treatment and type of blood collection tube. Type II collagen-specific biomarker Coll2-1 was measured using ELISA on all collected samples.
There was no significant difference on Coll2-1 values between samples collected at any of the five sampling times (p=0.85) or at any of the sampling days measured (p=0.58). None of the sampling parameters tested had a significant impact on Coll2-1 value (clotting time, clotting temperature and temperature of blood centrifugation (p=0.93), type of tube: p=0.38) when all data from healthy subjects were pooled (n=631 samples). On the contrary, differences were found in between subjects (p<0.001) and subjects with knee OA had a significantly higher Coll2-1 concentration then healthy subjects (p<0.001).
Coll2-1 assay is a biomarker of osteoarthritis that is sufficiently robust for use during OA clinical trials. Coll2-1 measurement is not affected by subject specific conditions such as fasting, resting state, circadian rhythm, seasonality, nor by sampling process factors such as type of dry tube, clotting patterns and centrifugation temperature.