Scientists Discover Game-Changing Therapy to Combat High Cholesterol

Scientists have discovered a potential new treatment for familial hypercholesterolemia, inspired by signs seen in the Mona Lisa.

Using human stem cells, they found compounds that lower cholesterol without relying on the usual pathways, providing a fresh approach to treating the condition.

A Hidden Clue in the Mona Lisa

Leonardo da Vinci’s Mona Lisa is one of the most famous paintings in the world. However, what many people don’t know is that it may also hold a clue to a medical condition called familial hypercholesterolemia (FH). Experts believe that the subtle fat deposits visible on her hands, known as xanthomas, could be early evidence of this genetic disorder.

FH is an inherited condition that raises the risk of heart disease by causing dangerously high levels of LDL, or “bad” cholesterol, in the blood. Under normal circumstances, a protein called the low-density lipoprotein receptor (LDLR) helps remove cholesterol from the bloodstream by transporting it into liver cells for breakdown. In individuals with FH, mutations in the LDLR gene impair this process, making it difficult for the liver to clear cholesterol effectively. As a result, cholesterol levels remain high, increasing the risk of cardiovascular problems. According to the American Heart Association, approximately 1 in 200 adults carry the FH mutation.

Patients with high cholesterol are often prescribed statins. Statins work to lower cholesterol by increasing levels of the LDLR; however, the effectiveness of statins varies greatly across the population, and patients with homozygous mutations in FH are resistant to statin treatment because their LDLR gene is mutated.

Searching for New Therapeutic Solutions

Researchers at the Medical University of South Carolina (MUSC) are working to discover new therapeutics. In work published in Communications Biology, they report the development of a novel system to screen for new therapeutic compounds that reduce the secretion of apolipoprotein B (apoB), the main protein component of the LDL particle, from liver cells. By screening the South Carolina Compound Collection (SC³), a collection of approximately 130,000 compounds, they found a class of molecules that lowered the secretion of apoB and reduced cholesterol levels. These molecules have the potential to offer a new treatment regimen for patients with FH.

A Unique Approach to Drug Discovery

“Our approach is the original way of doing pharmacology – trying to find drugs that can fix the disease without knowing how it fixes it,” explained Stephen Duncan, D.Phil., professor and SmartState Endowed Chair in the Department of Regenerative Medicine and Cell Biology at MUSC. “You model the disease, and then you can screen drugs to find out which ones work. Then you can work out retrospectively how the drug functions.”

“The nice thing about that is you are starting off by knowing the drug can actually fix the problem you hope to fix,” added Duncan.

Creating a Human Cell Model for Screening

To identify potential new therapeutics, Duncan and his research team – led by Ray (Jui-Tung) Liu, Ph.D., a postdoctoral scholar, and Caren Doueiry, a graduate student, lead authors for this study – created human liver-like cells from induced pluripotent stem cells (iPSCs). iPSCs are artificial stem cells derived from skin cells or blood cells. This technique allowed the team to produce large numbers of cells to screen a large library of chemical compounds. Using this model system, the team found a unique class of compounds that showed promise in treating FH.

“We found that apoB levels go way down when we give the cells the drug,” said Duncan. “Cholesterol levels go down. Triglyceride levels go down.”

Testing Promising Compounds in Mice

The team then tried testing these compounds in a preclinical mouse model. Surprisingly, however, these compounds were ineffective in the mouse. Further examination of mouse liver cells showed that the mouse cells were resistant to these compounds, highlighting a key difference between a human cell model and a mouse model.

To overcome this hurdle, the Duncan Lab, in partnership with Yecuris, used Avatar mice – mice that have been engineered to grow a liver from human cells, rather than mouse cells.

“We used a humanized mouse model – a mouse with ‘your’ liver in it,” explained Duncan.

This humanized mouse model is a powerful tool; the presence of the human-derived liver recapitulates the lipid profile seen in patients, and therefore represents a model to test new therapeutics in a complex system. The compounds identified in the iPSC screen were also effective in this complex animal model.

A New Path for FH Treatment

In summary, the Duncan Lab created a powerful system to model complex diseases and test for new therapeutic compounds. The team identified a novel class of compounds that effectively lowered cholesterol, triglycerides, and apoB. Importantly, these drugs work independently of the LDLR pathway, which is targeted by traditional therapies, and offer a novel therapy for patients with FH.

“Showing that you can use these human stem cells as a system to model disease, complete a drug discovery process, and find a drug that could potentially be used to treat a patient – that is the epitome of personalized medicine,” said Duncan. “This shows there is a very feasible way to do drug discovery using a human system.”

The Road Ahead in Drug Discovery

While this work is promising, there is still work to do.

“Finding what the drug target is and showing the mechanism of action is an absolute a priority,” he added.

Learning how the drug works is a critical next step and could identify other important proteins that could be targeted with other drugs. Another key question is how these compounds interact with conventional therapy, such as statins. Combining these drugs could have a powerful effect on lowering cholesterol by lowering both the cholesterol being made and the cholesterol circulating in the body.

Reference: “A human iPSC-derived hepatocyte screen identifies compounds that inhibit production of Apolipoprotein B” by Jui-Tung Liu, Caren Doueiry, Yu-lin Jiang, Josef Blaszkiewicz, Mary Paige Lamprecht, James A. Heslop, Yuri K. Peterson, Juliana Debrito Carten, Paula Traktman, Yang Yuan, Salman R. Khetani, Waleed O. Twal and Stephen A. Duncan, 24 April 2023, Communications Biology.
DOI: 10.1038/s42003-023-04739-9

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