August 2019

Transfecting Beyond the Germline Just Got Easier

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CRISPR-Cas9 is a fast and accurate tool for adding, removing or modifying genetic material at specific locations in the genome. The technology allows researchers to more easily alter DNA sequences and modify gene function than traditional gene editing techniques. It accomplishes this by exploiting the functionality of a bacterial immune system to cut DNA at targeted locations. The DNA repair machinery of the cell is then used to add/delete genetic material or even replace segments with customized DNA sequences. This gives researchers control over which genes are ultimately expressed in plants, animals and humans.

Most in vivo CRISPR edits are done to somatic cells, meaning they are cells other than egg and sperm cells. Any changes in gene expression that occur will be limited to just that organism. Edits made to germline cells (egg/sperm), however, are passed on to subsequent generations. The problem with editing germline cells is that microinjection is the current standard method. Microinjecting CRISPR directly into eggs or embryos frequently causes significant cell damage or death. Microinjections also take an inordinate amount of time and effort for offering such a low rate of successful delivery.

Researchers at the USDA, working closely with Phoreus Biotech, recently discovered an innovative way around this problem. By using branched amphipathic peptide capsules (BAPC) as a nanocarrier, they were able to microinject insects in the abdomen near ovaries to produce heritable germline gene editing in subsequent generations without causing cell death. This marks a significant advance in the ability to deliver CRISPR products and could completely revolutionize the application and usefulness of the technology in insects. Further research is being conducted to determine if BAPC-delivered CRISPR can be fed to adult insects and successfully make their way into embryos.