Engineers harness focused ultrasound to revolutionize CRISPR's capabilities to treat countless diseases.
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3 Dec, 2024
4 min read
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USC biomedical engineers have harnessed focused ultrasound to improve CRISPR, a revolutionary tool that enables the DNA in living organisms to be modified. Credit: Wang Lab and Pepper Workshop.
Thanks to the revolutionary advancements in CRISPR technology, medical specialists are on the verge of transforming how we approach the treatment and prevention of some of the most challenging genetic disorders and diseases.
CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) is a Nobel Prize-winning gene-editing tool that scientists are already using extensively to cut and modify DNA sequences, enabling them to activate or deactivate genes and even insert new DNA to correct genetic abnormalities. By harnessing the power of the Cas9 enzyme, CRISPR can alter DNA with unmatched precision.
Engineers from the USC Alfred E. Mann Department of Biomedical Engineering have now developed an update to the tool that will make CRISPR even more effective through the use of focused ultrasound. The new toolkit will enable precise targeting of CRISPR gene editing to the specific regions that need treatment. The research team is already working to apply this finding to improve their approach to cancer immunotherapy.
“CRISPR is revolutionary,” Dwight C. and Hildagarde E. Baum Chair in Biomedical Engineering Peter Yingxiao Wang said, “You can do genome or epigenome editing right in the cell nucleus — so that essentially, you can treat genetically-related diseases. But we are pushing it one step further to make it controllable. Instead of continuously editing the genome, we can now control it to be activated at a specific location and at a specific time using a non-invasive remote-controlled ultrasound wave. That’s the breakthrough.”
Wang and his lab have established themselves as leaders in the revolutionary field of focused ultrasound, significantly advancing cancer immunotherapy through the use of engineered Chimeric Antigen Receptor (CAR) T-cells. These powerful immune cells are isolated from patients and engineered to enhance their ability to target cancer. By employing ultrasound waves, Wang and his team can precisely govern these CAR T-cells, enabling them to zero in on tumor cells while protecting healthy tissue from damage.
In their latest study, the researchers illustrate the transformative potential of combining focused ultrasound with CRISPR technology, showing how this synergy can effectively work to eradicate cancer cells in mouse models. Wang emphasized that this innovative tool holds the promise of addressing a wide spectrum of genetic disorders, diseases, and autoimmune conditions, making it a game-changer in modern medicine.
“This is the first study that provides a very comprehensive, ultrasound-controllable CRISPR toolbox to knock out, activate, or silence a specific gene,” Assistant Professor of Biomedical Engineering Longwei Liu said. “Combining that with immunotherapy, we showed enhanced tumor treatment in mice.”
Wang noted that a significant drawback of CRISPR technology is its continuous gene-editing activity once activated and introduced into the body.
“With a continuous expression, this will lead to the immunogenicity in humans because a human body will recognize the Cas9 positive cells and attack these kinds of cells,” Liu said
“Of course, that would trigger unwanted features. If it’s continuously working, sometimes you want to stop it, but you can’t. In our controllable system, you can flip it on and off whenever you want. So that’s the beauty of the system – providing another layer or controllability, and therefore precision,” Wang said.
However, researchers are addressing this challenge using focused ultrasound, which employs ultrasound waves to induce a temperature change at specific sites where the CRISPR protein needs to be activated. For example, this site might be a tumor where CRISPR needs to alter the DNA of cancerous cells to enhance their vulnerability to CAR T-cell-based immunotherapy.
“So essentially, you connect the ultrasound wave through the temperature change to the production of the CRISPR molecule,” Wang said. “As soon as you turn it on, the CRISPR molecule will start to do its job wherever you want it. Then, after a certain time, it will start to decay by itself, it will be shut down for a period, and then you can turn it on again whenever you want.”
In their cancer-fighting research, the team effectively employed focused ultrasound-enabled CRISPR to hone in on telomeres—those vital DNA-protein structures at chromosome ends thatthat serve to safeguard chromosome integrity and limit cellular division.
“The telomere has many, many repeats, and we use CRISPR, guided by ultrasound, to cut this telomere so that it will trigger the chromosome to be cut off at two ends,” Wang said. “Because they have a repeatable sequence, they will all be cut, and therefore, the tumor cell can no longer repair itself. It’s all broken. The cell will then undergo apoptosis and die.”
Wang explained that the cells would initiate cytokine production—proteins secreted by immune cells that serve as signals to draw other immune cells to the area to target the already-dying tumor cells. The research team’s approach enhances the cancer-fighting effect by introducing their SynNotch CAR T-cells—engineered to specifically target cancer cells that express a protein called CD19 (which is activated by the CRISPR tool), thereby minimizing damage to healthy cells. Wang noted that the tumor surface functions as a training ground for these CAR T-cells.
“And following their training, these SynNotch CAR T-cells will start to produce a CAR receptor on the surface to target the whole population of the tumor,” Wang said. “With those three factors together, we reach really high efficiency for tumor cleaning.”
The team has shown promising laboratory results by utilizing the focused ultrasound CRISPR tool alongside CAR T-cell technology.
“The result was surprisingly good,” Wang said. “In all the mice, the tumor was not only slowing in growth but it also got cleared — the tumor essentially decayed and disappeared. So, these are very encouraging results.”
Journal reference:
- Yiqian Wu, Ziliang Huang, Yahan Liu, Peixiang He, Yuxuan Wang, Liyanran Yan, Xinhui Wang, Shanzi Gao, Xintao Zhou, Chi Woo Yoon, Kun Sun, Yinglin Situ, Phuong Ho, Yushun Zeng, Zhou Yuan, Linshan Zhu, Qifa Zhou, Yunde Zhao, Thomas Liu, Gabriel A. Kwong, Shu Chien, Longwei Liu & Yingxiao Wang. Ultrasound Control of Genomic Regulatory Toolboxes for Cancer Immunotherapy. Nature Communications, 2024; DOI: 10.1038/s41467-024-54477-7
