DNA-Based Therapy Reduces LDL Cholesterol by 47 Percent in Preclinical Trials

Researchers from the University of Barcelona and the University of Oregon have developed an experimental DNA-based therapy that significantly lowers low-density lipoprotein (LDL) cholesterol levels in preclinical models. By targeting the PCSK9 protein, which regulates the body's ability to clear cholesterol from the bloodstream, the team achieved a 47 percent reduction in cholesterol levels in transgenic mice following a single injection. The findings, published in the journal Biochemical Pharmacology, offer a potential new pathway for cardiovascular treatment that operates independently of traditional statin medications.

The study centers on the use of polypurine reverse Hoogsteen (PPRH) hairpins, which are specialized, single-stranded DNA molecules. These molecules are engineered to bind to specific gene sequences, effectively interfering with the transcription process that produces the PCSK9 protein. By suppressing this protein, the therapy increases the availability of LDL receptors on cell surfaces, allowing the body to more efficiently remove circulating cholesterol. This mechanism represents a shift from conventional pharmacological approaches, aiming to address the root cause of cholesterol accumulation at the genetic level.

At the heart of this experimental therapy is the use of PPRHs, which function as therapeutic oligonucleotides. These molecules are designed to recognize and bind to polypyrimidine sequences within the PCSK9 gene. According to Professor Carles J. Ciudad of the University of Barcelona, the binding process is highly specific. One arm of each PPRH chain attaches to exons 9 and 12 of the PCSK9 gene through Watson-Crick bonds, which disrupts the activity of RNA polymerase or prevents transcription factors from initiating the gene expression process.

This targeted interference effectively reduces the production of PCSK9 RNA and the subsequent synthesis of the protein itself. By lowering the levels of this protein, the therapy prevents the degradation of LDL receptors, which are essential for capturing and clearing LDL cholesterol from the blood. The researchers tested two specific PPRH variants, designated HpE9 and HpE12, both of which demonstrated significant efficacy in human liver cell cultures, with HpE12 reducing PCSK9 protein levels by 87 percent.

To evaluate the therapy in a living system, the research team utilized transgenic mice engineered to express the human PCSK9 gene. The administration of a single injection of the HpE12 molecule yielded notable results, with plasma PCSK9 levels dropping by 50 percent and total cholesterol levels falling by 47 percent within three days of treatment. These findings suggest that the PPRH-based approach is capable of producing a rapid and substantial physiological response in a controlled environment.

Professor Verònica Noé, who co-led the study, highlighted the consistency of these results across both cellular and animal models. The ability to achieve such significant reductions in cholesterol with a single dose underscores the potential potency of this gene-silencing technique. While these results are promising, the researchers emphasize that the current data is limited to preclinical models, and further investigation is required to establish the safety and efficacy of the treatment for human patients.

Targeting PCSK9 is not a new concept in cardiovascular medicine, as the protein has been a primary focus for drug development over the last decade. Current therapies, such as monoclonal antibodies like evolocumab and alirocumab, as well as siRNA-based medications like inclisiran, are already used to manage high cholesterol. These existing treatments work by either binding to the protein or preventing its production, but they often require regular, recurring administration.

The research team posits that their PPRH-based approach offers distinct practical advantages over these established methods. They highlight the relatively low cost of synthesizing these DNA molecules, their inherent stability, and a low likelihood of triggering an unwanted immune response in the body. Furthermore, the researchers suggest that this method avoids the common side effects associated with statin therapy, such as myopathies, which can limit patient adherence to traditional cholesterol-lowering regimens.

Despite the success observed in the laboratory and in transgenic mice, the transition to human clinical trials remains a significant hurdle. The researchers acknowledge that extensive testing is necessary to ensure that the PPRH molecules do not cause off-target effects or unintended genetic interference. The development of a delivery system that can safely and effectively transport these DNA molecules to the liver in human patients will be a critical focus of future research efforts.

If subsequent studies confirm that the therapy is safe and effective in humans, it could provide a versatile new tool for managing hypercholesterolemia. The ability to modulate cholesterol levels through a single, stable, and cost-effective injection could potentially improve long-term outcomes for patients at risk of atherosclerosis and heart disease. The project, supported by the Spanish Ministry of Science, Innovation and Universities and the U.S. National Institutes of Health, continues to explore the therapeutic potential of these polypurine hairpins.