Human T-cells Reprogrammed for Therapeutic Purposes with CRISPR-Cas9, Researchers Say

Joana Carvalho, PhD avatar

by Joana Carvalho, PhD |

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A team of scientists from the University of California San Francisco has developed an innovative technique to genetically engineer genes involved in the body’s immune response. This new approach has the potential to revolutionize the way autoimmune diseases, such as lupus, rheumatoid arthritis, cancer, and HIV are treated. 

The findings are described in the study, “Reprogramming human T cell function and specificity with non-viral genome targeting,” published recently in Nature.

Scientists have been trying to genetically reprogram human T-cells — the killers in our immune system —  for therapeutic purposes for decades.

However, standard techniques involved the use of virus to deliver genetically modified genes to specific regions within the cell’s genome. Besides being highly unspecific, expensive, and time-consuming, this technique also required the introduction of toxic viruses inside cells, which could cause serious damage.

Now, researchers may have found a better alternative — using the genome-targeting system CRISPR-Cas9 that does not rely on toxic virus to deliver genes, allowing fast and efficient insertion of large DNA sequences into specific regions of the T-cell’s genome without compromising their viability and immune function.

“This new technology creates an opportunity to speed development and testing of therapeutic strategies in lupus by offering researchers new ways to modify particular genes that contribute to the disease,” Gerald Nepom, MD, PhD, said in a press release. Nepom is co-chair of the Lupus Research Alliance Scientific Advisory Board and Director of the Immune Tolerance Network (ITN).

With this technique, researchers now are able to introduce single or several genetic modifications at once into one specific region of interest within the cell’s genome.

In this study, investigators first used cells from patients with an autoimmune disease caused by mutations in the IL2RA gene, which encodes for interleukin 2 receptor alpha, a protein receptor involved in the regulation of immune tolerance.

By correcting these mutations, they were able to improve cell-signaling, demonstrating that CRISPR-Cas9 could be used to correct single mutations within a gene.

They then used the same approach to insert a large DNA sequence encoding a modified T-cell receptor (TCR) designed to redirect T-cells toward the cancerous substances. The T-cells containing the genetically engineered TCR were able to detect tumor proteins and trigger an anti-tumor immune response both in lab-grown cells and in animal models.

Altogether, these findings provide strong preclinical evidence that non-viral genome targeting is a versatile technique that can be used to genetically manipulate human immune cells for therapeutic purposes. Moreover, it is able to do so in a fast and efficient way, without compromising T-cells’ viability.

“Our therapeutic gene editing in human T cells is a process that takes only a short time from target selection to production of the genetically modified T cell product. In approximately one week, novel gRNAs and DNA repair templates can be designed, synthesized, and the DNA integrated into primary human T cells that remain viable, expandable, and functional,” researchers wrote.

Going forward, investigators note there are still a lot of challenges that need to be overcome to bring this type of gene-editing tool to the clinic.

“Much work remains to be done to improve our understanding of endogenous T cell circuitry if we are going to create synthetic circuits,” they said.