Genetic Alteration of Individual Animal Cells

Scientists at ETH Zurich have devised a technique for genetically modifying individual cells separately within animals. This innovation streamlines the research process, eliminating the need for numerous animal experiments. By applying this novel approach, the scientists have pinpointed genes linked to a severe, rare genetic disorder.

Typically, investigating the genetic origins of diseases involves deactivating a single gene in animals and observing the resulting effects on the organism. However, for numerous diseases, the pathology is influenced by multiple genes, complicating the task of identifying each gene’s contribution to the disease. This complexity has traditionally required conducting multiple animal experiments, each targeting a specific gene modification.

Under the leadership of Randall Platt, a Professor of Biological Engineering at the Department of Biosystems Science and Engineering at ETH Zurich in Basel, researchers have introduced a groundbreaking approach that promises to streamline and expedite animal-based research.

They employ the CRISPR-Cas gene-editing tool to simultaneously introduce several dozen gene modifications into the cells of a single animal, creating a mosaic-like pattern. Although each cell is modified with just one gene alteration, different cells within an organ undergo distinct modifications. This technique enables precise analysis of individual cells, facilitating in-depth exploration of the ramifications of genetic changes.

Altering animal cells genetically: First time in adult animals

The researchers at ETH Zurich have, for the first time, applied this method to adult animals, specifically adult mice. They detail their achievement in the latest edition of Nature. Prior to this, scientists had primarily employed a similar technique on cells cultured in a laboratory or animal embryos.

The researchers employed the adeno-associated virus (AAV) to guide mouse cells in deactivating specific genes with CRISPR-Cas gene editing. This delivery method can effectively target any organ. They designed the viruses so that each virus particle carried instructions to deactivate a specific gene.

The mice were then exposed to a mixture of these viruses, each with distinct gene deactivation instructions. Consequently, various genes within the cells of a single organ were deactivated. The researchers chose the brain as the focus of this study.

To conduct their experiment on mice, the researchers honed in on 29 genes from this particular chromosomal region that exhibit activity within the mouse brain. They proceeded to manipulate one of these 29 genes within each individual mouse brain cell and subsequently assessed the RNA profiles of these brain cells.

Their investigation unveiled that three of these genes play a pivotal role in the malfunction of brain cells. Furthermore, they identified patterns in the mouse cells that bear resemblance to those associated with conditions like schizophrenia and autism spectrum disorders. One of these genes was known, while the other two were less studied.

António Santinha, the lead author of the study and a doctoral student in Platt’s group, noted, “Identifying genes with abnormal activity in a disease can guide drug development.”

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The methodology is also well-suited for examining various other genetic disorders. According to Santinha, In many congenital diseases, multiple genes play a role, not just one, Santinha says.

“This is also the case with mental illnesses such as schizophrenia. Our technique now lets us study such diseases and their genetic causes directly in fully grown animals.” Furthermore, there is potential to expand the number of genes modified in each experiment from the current 29 to several hundred.

One significant advantage is the ability to conduct these analyses in living organisms, as cellular behavior differs between cultures and within living organisms, as noted by Santinha. Additionally, the researchers can conveniently administer the adeno-associated viruses (AAVs) through intravenous injection into the animals’ bloodstream.

Multiple AAVs with distinct functional characteristics are available, and for this particular study, researchers employed a virus that penetrates the animals’ brains. Santinha explains, “Depending on the specific investigative focus, AAVs targeting other organs could also be used.”

ETH Zurich has submitted a patent application for this technology, and the researchers intend to incorporate it into a spin-off venture they are establishing.

Altering animal cells genetically: Disrupting the Genome

CRISPR perturbation involves mosaic-like genome editing using CRISPR-Cas tools. This approach is transforming life sciences research by gathering ample data. It could accelerate complex disease research.

Another ETH Zurich research team recently demonstrated CRISPR perturbation in organoids. Organoids are microtissue spheroids grown from stem cells, closely mimicking the structure of real organs, essentially serving as miniature organs. They provide an animal-free research approach that complements animal-based research.They could reduce the need for animal testing.

Read the original article on sciencedaily.

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