Evaluation of DNA extracted from residual blood clots after serological testing

DNA quality is of paramount importance for molecular biology research. This study aimed to assess the DNA extracted from residual blood clots after serological testing, focusing on the impact of blood clot segments, extraction kits, temporary storage durations (TSDs), and thawing methods on DNA quality. We divided the residual blood clot column (BCC) from healthy donors into three segments and utilized two different extraction kits. The BCCs were subjected to four TSDs at 4°C (7 days, 10 days, 1 month, and 2 months) and three thawing methods (4°C, room temperature, and 37°C). We found that the TIANamp Blood Clot DNA Kit yielded consistently high-quality DNA from each segment with stable A260/280 and A260/230 ratios. The DNA yield showed a strong positive correlation with leukocyte concentration, and a satisfactory median DNA yield of 28.79 μg/g BCC was obtained across all segments. DNA integrity, as measured by the DNA integrity number and DNA fragment peak size, decreased with increasing TSD at 4°C, with a notable decrease after 10 days of storage. Thawing at 37°C resulted in the lowest DNA fragment peak size. In conclusion, BCC could be an ideal DNA source with satisfactory yield and purity. A prolonged TSD at 4°C leads to an obvious decrease in DNA integrity, and thawing the frozen BCC at 37°C decreases DNA fragment sizes. To maintain DNA integrity, BCCs should be cryopreserved as soon as possible after short TSDs at 4°C and thawed at 4°C.