How can one of the most important forensic investigative procedures be so flawed? Currently, the analysis of sexual assault kits is tedious and requires skilled technicians, yet still fails to recover large amounts of DNA evidence. InnoGenomics plans to change this by giving laboratories a scalable sperm extraction solution to help make the sexual assault kit processing fully automated, while preserving the integrity of samples.
In the conventional methodology, the initial sample is eluted off the collection media and into a centrifuge tube. Digestion of the epithelial cells leaves behind a solution with suspended sperm cells and epithelial DNA. The sperm cells are centrifuged into a pellet, and a technician must decant the liquid fraction of the sample away from the pellet, wash the pellet numerous times to reduce epithelial DNA carryover, then digest the sperm pellet.
In doing so, even the most skilled technicians can remove up to 60% of the male DNA present in the sample. In a sample with a low concentration of male DNA, this can mean the difference between justice and an inconclusive test.
To solve these issues of sample loss and inefficiency, InnoGenomics teamed up with Hamilton Company, a leading global manufacturer in automated liquid handling workstations and sample management systems. The result is SpermTrap.
Now in beta, SpermTrap is available to our testing partners in a manual or automated version. With a basket-in-tube centrifuge system, the sample can be digested with the basket in a lowered position. Pull and twist-lock the basket up, and then centrifuge the entire device. The sample will run through InnoGenomics’ specialized matrix material filter, which is designed to catch and hold sperm. The solution of digested epithelial cells washes through the material and collects in the lower tube.
The liquid fraction on the bottom can then be collected and processed—without compromising any of the sperm locked within the matrix. This method removes a significant source of error: the pipette. A new tube is quickly added to the bottom, and the trapped sperm pellet can then be digested and spun down into its own solution.
Using this method with InnoGenomics’ specialized sperm filter, SpermTrap can retain up to 92% of the male DNA, a more than 20% increase over conventional extractions. Further, the device carries over less than .05% of the female DNA from the media within the sperm fraction. Even in highly mixed samples with low levels of male DNA, SpermTrap outperforms other methods.
But more importantly, SpermTrap increases a laboratory manager’s ability to automate the process completely. And, while considering an upgrade to the fully automated sexual assault kit processing system, labs can try the manual version of SpermTrap to prove the concept directly. The manual version requires no upgrade, as it’s compatible with tools and workflows common in today’s forensics labs.
To carry out the process manually, technicians can use the SpermTrap system in most tabletop centrifuge machines. For users who want to fully automate the process, the SpermTrap system is fully compatible with Hamilton’s AutoLys SAE Star. Automating the last remaining manual steps can greatly increase efficiency.
InnoGenomics will host a SpermTrap training workshop in spring 2019. If your lab is interested in either attending the workshop or becoming a beta tester for SpermTrap, send your inquiries to InnoGenomics at [email protected]. SpermTrap is set to enter the market in early 2019.