In this study, researchers have established a new way to capture the detailed biomechanical properties of heart tissue. The high-resolution optical technique fills an important technology gap necessary to develop and test therapies that might eventually be used to heal heart damage after a heart attack. The study published in the journal Biomedical Optics Express.

Heart attacks occur when a blood clot prevents the coronary artery from delivering oxygen-rich blood to the heart. This blockage deprives the heart muscle of oxygen and within a short time causes permanent damage in the form of scarred tissue. This damage takes away energy from the beating heart and affects how well it can contract to pump blood.

Researchers report results from studies in mice showing that a high-resolution technique known as optical coherence elastography (OCE) can be used to compare the mechanical properties of healthy tissue and tissue scarred by an induced heart attack. The researchers plan to use the technique to evaluate the effectiveness of therapies aimed at reversing damage to heart tissue.

Regenerating heart tissue

The researchers turned to OCE, a technique developed in Larin's lab, to see if it might be useful for observing how well experimental therapies worked in mouse models. OCE is based on the biomedical imaging technique optical coherence tomography (OCT), which can provide high resolution images of the microstructures of tissue.

However, rather than obtaining structural information, OCE uses the principles of OCT to create high-resolution maps of tissue mechanics. OCE is ideal for observing the tissue mechanics in mouse hearts because it has the resolution necessary to detect whether the boundary between healthy and scarred tissue moves in response to therapy.

Performing OCE requires mechanical waves to be inducted in the tissue. Much like a stone dropped into water causes a pattern of waves, tissue exposed to a small mechanical force will exhibit a specific pattern of waves propagating through it. "Because of the small size and delicate nature of the mouse heart, we had to make special equipment to generate very small perturbations on the tissue," said Larin.

Examining tissue after a heart attack

The researchers tested their imaging approach in tissue samples from mice. After an induced heart attack, the mice developed scarring that would be similar to that caused by a heart attack in people. Researchers observed the damaged tissue was showing directionally of the wave propagation compared to healthy tissue. This observation indicated that the muscle fibers in the damaged area were more disorganized than healthy tissue.

They also saw differences in tissue stiffness between healthy and damaged tissue using OCE. Further study involves that they need to use the technique to examine regenerated heart tissue to help us find a therapy that can benefit the millions of people worldwide who have experienced a heart attack.