Scientists use CRISPR gene-editing technology to remove HIV virus from humanised mice

Scientists using CRISPR gene-editing technology have removed HIV DNA from three different animals, including a “humanised” variant of mice that had human immune cells transplanted into them and had been infected with the virus.

In the study, published today in the journal Molecular Therapy, the team genetically inactivated HIV-1 in humanised transgenic mice. Scientists were able to reduce the RNA expression of viral genes by roughly 60 to 95%.

The team, which was made up of scientists from the Lewis Katz School of Medicine at Temple University (LKSOM) and the University of Pittsburgh, used an animal model where latent HIV-1 infection was housed in humanised mice implanted with human immune cells, including T cells the HIV-1 virus.

“These animals carry latent HIV in the genomes of human T cells, where the virus can escape detection,” said Wenhui Hu, associate professor in the Center for Metabolic Disease Research and the Department of Pathology.

However, following a single treatment with CRISPR viral fragments were successfully removed from the infected human cells embedded in mouse tissues and organs.

Scientists tested their system in mice acutely infected with EcoHIV, the mouse equivalent of human HIV-1.

In 96% of mice infected with EcoHIV excision using the CRISPR technique worked effectively, providing the first evidence for HIV-1 eradication by prophylactic treatment with a CRISPR/Cas9 system.

“During acute infection, HIV actively replicates,” said Kamel Khalili, Laura H. Carnell professor and Chair of the Department of Neuroscience, Director of the Center for Neurovirology, and director of the Comprehensive NeuroAIDS Center at LKSOMDr.

“With EcoHIV mice, we were able to investigate the ability of the CRISPR strategy to block viral replication and potentially prevent systemic infection.”

Image courtesy of Ian Slaymaker, Broad Institute.

The scientists’ work builds on a previous proof-of-concept study that the team published in 2016, in which they used transgenic rat and mouse models with HIV-1 DNA incorporated into the genome of every tissue of the animals’ bodies.

In that study they demonstrated that their strategy could delete the targeted fragments of HIV-1 from the genome in most tissues in the experimental animals.

“Our new study is more comprehensive,” said Hu. “We confirmed the data from our previous work and have improved the efficiency of our gene editing strategy. We also show that the strategy is effective in two additional mouse models, one representing acute infection in mouse cells and the other representing chronic, or latent, infection in human cells.”

From here, the scientists want to repeat their study first in primates before, eventually, testing CRISPR’s ability to remove HIV-1 DNA in human clinical trials.

“The next stage would be to repeat the study in primates, a more suitable animal model where HIV infection induces disease, in order to further demonstrate elimination of HIV-1 DNA in latently infected T cells and other sanctuary sites for HIV-1, including brain cells,” said Khalili.

“Our eventual goal is a clinical trial in human patients.”

Gene-edited stem cells raise hopes for arthritis vaccine

Scientists have successfully edited mice stem cells to combat arthritis-related inflammation, in research that could one day lead to a human vaccine to treat the chronic condition.

The edited stem cells are part of an emerging group known as SMART cells (stem cells modified for autonomous regenerative therapy) and are designed to develop into cartilage cells that have the ability to produce a type of anti-inflammatory drug known as a biologic.

This means that – at least in theory – they would not only replace lost cartilage but also continually protect joints and the surrounding tissue from the damage normally associated with chronic inflammation.

As a result, they could offer a dramatic improvement over conventional arthritis treatments, which target a molecule in the immune system known as TNF-alpha (tumour necrosis factor-alpha) responsible for producing inflammation. These drugs can be very effective at combating arthritis but as they impact on the entire immune system, can also produce some unwanted and often extremely unpleasant side-effects.

Study lead author Dr Farshid Guilak explains the research to Jim Dryden of Washington University BioMed Radio

The research, which has been published today in the journal Stem Cell Reports, was conducted by a network of US scientists from Washington University School of Medicine, Shriners Hospitals for Children, Duke University and Cytex Therapeutics.

The scientists hope to develop the research into a sophisticated vaccine that would allow highly targeted treatment of arthritis.

“Our goal is to package the rewired stem cells as a vaccine for arthritis, which would deliver an anti-inflammatory drug to an arthritic joint but only when it is needed,” said study lead author Dr Farshid Guilak, a professor of orthopedic surgery at Washington University School of Medicine.

“We want to use our gene-editing technology as a way to deliver targeted therapy in response to localized inflammation in a joint, as opposed to current drug therapies that can interfere with the inflammatory response through the entire body.

“If this strategy proves to be successful, the engineered cells only would block inflammation when inflammatory signals are released, such as during an arthritic flare in that joint.”

A conceptual depiction of the edited stem cell, which was modified using CRISPR technology. Image courtesy of Ella Marushchenko

The SMART cells were developed by growing mice stem cells in a test tube and then editing them using CRISPR gene editing technology to change the way the stem cells responded to inflammation. They were then able to grow the modified stem cells in cartilage tissue-producing cells, which they found were protected from inflammation that would normally impact on non-edited cartilage tissue.

Having achieved this vital first stage, the researchers plan to attempt to first replicate the achievement in animals, before moving on to research in humans with a goal of producing a vaccine or other therapy that can be used on patients.

They also believe the approach could be used for cell types, and therefore different medical conditions.

“We believe this strategy also may work for other systems that depend on a feedback loop. In diabetes, for example, it’s possible we could make stem cells that would sense glucose and turn on insulin in response,” explained Guilak.

“We are using pluripotent stem cells, so we can make them into any cell type, and with CRISPR, we can remove or insert genes that have the potential to treat many types of disorders.”