Image: The flexible tissue scaffold unfolds from a glass pipette with a tip one millimeter wide (Photo courtesy of Miles Montgomery).
An innovative, elastic shape-memory scaffold can be used for minimally invasive delivery of functional tissues, according to a new study.
Researchers at the University of Toronto (Canada), the Hospital for Sick Children (Toronto, Canada), and other institutions used the citrate-based biodegradable polymer poly(octamethylene maleate (anhydride) citrate (POMaC) to microfabricate a latticed scaffold that can be used for functional delivery of various tissues. Both scaffold and tissue patches up to 1×1 cm can be delivered by injection through an orifice as small as 1 mm, unfurling to their initial shape without affecting viability and function.
In a subcutaneous syngeneic rat model, injection of cardiac patches was found to be equivalent to open surgery when comparing vascularization, macrophage recruitment, and cell survival. The cardiomyocyte patches significantly improved cardiac function following an induced myocardial infarction (MI), when compared with the untreated controls. The researchers also successfully achieved delivery of human cell-derived patches to the epicardium, aorta, and liver in a porcine model. The study was published on August 14, 2017, in Nature Materials.
“The shape-memory effect is based on physical properties, not chemical ones. The unfolding process doesn't require additional injections, and won't be affected by the local conditions within the body,” said senior author professor of biomedical engineering Milica Radisic, PhD, of the University of Toronto. “You could customize this platform, adding growth factors or other drugs that would encourage tissue regeneration. We think it would significantly improve quality of life.”
“At the beginning it was a real challenge; there was no template to base my design on, and nothing I tried was working. But I took these failures as an indication that I was working on a problem worth solving,” said Miles Montgomery, a PhD candidate at the University of Toronto. “When we saw that the lab-grown cardiac tissue was functional and not affected by the injection process, that was very exciting. Heart cells are extremely sensitive, so if we can do it with them, we can likely do it with other tissues as well.”
University of Toronto
Hospital for Sick Children