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This three-dimensional model of a left heart ventricle was engineered with a nanofiber scaffold seeded with heart cells. It could be used to study diseases, test drugs and develop patient-specific treatments for heart conditions such as arrhythmia. (Credit: Luke MacQueen and Michael Rosnach/Harvard University)

Researchers have bioengineered a three-dimensional model of a human left heart ventricle that could be used to study diseases, test drugs, and develop patient-specific treatments for heart conditions such as arrhythmia.

The researchers exposed the tissue to isoproterenol, a drug similar to adrenaline, and measured as the beat-rate increased just as it would in human and rat hearts. The researchers also poked holes in the ventricle to mimic a myocardial infarction, and studied the effect of the heart attack in a petri dish that resulted.

The tissue is engineered with a nanofiber scaffold seeded with human heart cells. The scaffold acts like a 3D template, guiding the cells and their assembly into ventricle chambers that beat in vitro. This allows researchers to study heart function using many of the same tools used in the clinic, including pressure-volume loops and ultrasound.

The key to building a functional ventricle is recreating the tissue’s unique structure. In native hearts, parallel myocardial fibers act as a scaffold, guiding brick-shaped heart cells to align and assemble end-to-end, forming a hollow, cone-shaped structure. When the heart beats, the cells expand and contract like an accordion.

To recreate that scaffold, the researchers used a nanofiber production platform known as pull spinning. The fiber travels in a spiral trajectory and solidifies before detaching from the bristle and moving toward a collector. To make the ventricle, the researchers used a combination of biodegradable polyester and gelatin fibers that were collected on a rotating collector shaped like a bullet. Because the collector is spinning, all of the fibers align in the same direction.

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