Potential of Methylene Blue to Shield Lungs During Major Heart Surgeries: New Research

Recent scientific research indicates that methylene blue, a medication already approved for various medical conditions, may offer protective benefits for the lungs during complex cardiac surgeries involving circulatory arrest and hypothermia. These procedures, such as aortic arch repairs, require temporarily stopping blood flow and cooling the body to safeguard vital organs, but they pose significant risk of lung damage, particularly acute lung injury (ALI). ALI affects over one-third of patients undergoing such surgeries and can lead to prolonged ventilation, extended hospital stays, and even fatalities.

The injury mechanism involves sudden reoxygenation of the lungs, which triggers inflammation and oxidative stress, damaging lung tissues. Currently, there are no specific treatments to prevent or reduce ALI post-surgery.

A groundbreaking study conducted in China explored whether methylene blue could mitigate lung damage in this context. Known for treating methemoglobinemia and carbon monoxide poisoning, methylene blue also exhibits anti-inflammatory and antioxidant properties. Researchers utilized a rat model simulating human-like circulatory arrest procedures. Some rats received methylene blue injections before surgery, while others did not, and additional groups were tested with compounds affecting molecular pathways related to inflammation and oxidative stress.

Post-surgery evaluations revealed that rats treated with methylene blue experienced significantly less lung injury, with lower inflammation, preserved tissue structure, and more stable blood oxygen and pH levels. Lung tissues from untreated rats showed inflammation, tissue thickening, and cell death, whereas those treated with methylene blue displayed fewer signs of damage.

The study also demonstrated that methylene blue modulates immune responses by reducing inflammatory markers and shifting immune cells towards tissue repair. It decreases reactive oxygen species (ROS), balancing the oxidative environment in the lungs. Importantly, methylene blue inhibits activation of the NLRP3 inflammasome, a protein complex involved in cell death and inflammation, thereby reducing further tissue damage.

According to the lead author, the safety profile and existing clinical use of methylene blue make it a promising candidate for repurposing to improve surgical outcomes. The research indicates that its antioxidant and immune-regulatory effects are key to its protective role.

While these findings are preliminary and based on animal models, they pave the way for future clinical trials. Further studies will explore optimal dosing, timing, and efficacy in patients with underlying health issues common among cardiac surgery candidates. If confirmed in humans, methylene blue could be a cost-effective strategy to prevent lung complications, enhance recovery, and increase survival rates in patients undergoing major heart surgeries.

Source: https://medicalxpress.com/news/2025-05-methylene-blue-lungs-complex-heart.html