Differential extraction: a comparison of SpermX and Sampletype i-sep DL-MB

Abstract

Differential extraction is a modified extraction that was developed in 1985 to separate male DNA (sperm cells) from female DNA (epithelial cells) in mixed samples. This process presents challenges such as the loss of male spermatozoa cells and the potential for epithelial cell carryover. Recent advancements in DNA analysis kits have improved separation during the differential extraction process. In this project, Biotype’s Sampletype i-sep® DL-MB and InnoGenomic’s SpermXTM kits were compared to a variation of the Qiagen DNA Investigator Kit to determine cell separation efficiency and sensitivity. Ease of use and processing time were also taken into consideration. Mixed samples at semen concentrations of neat, 1:10, and 1:100 dilutions were created and extracted according to the kit protocols and quantified with Quantifiler TrioTM. Results obtained from triplicate testing show that SpermXTM is highly effective at isolating the sperm fraction from neat and 1:10 sperm samples. SpermXTM yielded an average of 0.75 ng/μl compared to 0.22 ng/μl for neat and 0.12 ng/μl compared to 0.041 ng/μl for 1:10, when correlated with i-sep® DL-MB. Conversely, the i-sep® method outperforms SpermXTM in extracting DNA from the epithelial fraction. Notably, the DNA quantities from SpermXTM at 1:100 dilution were similar to those from i-sep® at the same dilution (0.031 ng/μl and 0.028 ng/μl), and both methods surpassed the Qiagen DNA Investigator Kit. Future applications for SpermXTM and i-sep® DL-MB would be to develop a way for the protocols to be automated or for the kits to be used in cold cases.