Tha-thump. Tha-thump. It’s magical and slightly unsettling to see that intimate beating of our hearts replicated in a petri dish. For biomedical engineer Nenad Bursac, it’s just part of his job.
Before becoming a professor at Duke, Bursac spent years cultivating heart muscle cells in glassware, coaxing them to not just stay alive but pulse like the real thing. “The first time I saw them beating, I was so excited I jumped up and down,” Bursac said. He had a vision that these strips of quivering tissue could be used to treat heart attacks. A “cardio patch,” he calls it.
Testing in rats showed promise, and pigs also responded well. Now, there are teams in Germany and Japan testing a similar approach in clinical trials with real people. Bursac doesn’t mind the competition: “My life’s mission is to save at least one person,” he said. “That’s what I signed up for. I’ll try everything I can.”
That includes a new approach Bursac is spearheading at Duke: gene therapy. He envisions delivering genetic instructions to injured hearts so they can regain function by building more sodium channels. This protein machinery guides salt ions across cellular membranes, orchestrating the electrical and mechanical cycles of heart muscles. Introducing more sodium channels to damaged heart tissue kicks it back into gear.
It’s an elegant solution. Instead of open-heart surgeries and heart transplants, this gene therapy could be just a single shot delivered to failing hearts.
But there’s a catch. Sodium channels are made of relatively big proteins, which have correspondingly large genetic instructions. Too long, in fact, to fit in the benign viruses currently used to deliver gene therapies to cells in the body.
Bursac’s workaround somehow sounds even more like science fiction than everything he’s done so far. Bacteria have sodium channels, too, but they are much smaller than ours, so Bursac has been reengineering bacterial sodium channels for use in human tissue. His lab has tested them on the cardio patches – a fine-tuned testing platform now – as well as in various animal models. The results are promising, and Bursac is itching to take this into clinical trials in the hopes of saving that one person.
The potential impact is much more than one person, of course. Cardiovascular issues are the leading cause of death worldwide, with a lack of treatments that restore healthy tissue function after injury. But with the steady drumbeat of work by researchers like Bursac, hope glitters on the horizon. Tha-thump. Tha-thump.
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