Marcelo Muñoz was waiting in line at a festival food truck, eyeing a batch of fried churros, when inspiration struck – an idea so sweet it could mark a seismic shift in the future of coronary artery disease treatment.

A pharmacist and chemist in the Bio-Engineering and Therapeutic Solutions (BEaTS) Laboratory at the Ottawa Heart Institute, Muñoz (PhD) and BEaTS director Emilio Alarcón, PhD, had spent weeks with their team exploring new ways to make bypass surgery procedures safer and more efficient using bioengineered materials.

“We’d been trying to figure out how to create blood vessels for use inside the body quickly and reliably,” he recounted. “That churro machine was the spark we needed that showed a possible path forward.”

As dough was extruded from a machine, Muñoz observed how it wrapped perfectly around a central rod to form a hollow cylinder before being dropped in bubbling oil, crisping into a golden, cinnamon sugar-coated tube.

“I thought – why not do something similar for a blood vessel,” he said.

That churro-stand moment became a turning point. In the years since, Muñoz, Alarcón, and the BEaTS team have worked to miniaturize the process and adapt it using biopolymers – naturally derived or engineered materials that are safe for use inside the body.Churros are deep-fried dough pastries, typically coated in sugar and often served with chocolate or caramel dipping sauce.

Affectionately dubbed The Churro Project among colleagues, Muñoz’s idea is now the basis for a bold new device designed to fabricate vascular grafts directly inside the human body – potentially eliminating the need for open-chest surgery.

Their concept was recently detailed in the peer-reviewed journal Advanced Materials Technologies.

The need for innovation

Each year, thousands of patients in Canada undergo coronary artery bypass graft (CABG) surgery.

The standard procedure involves removing a healthy blood vessel from elsewhere in the patient’s body and grafting it onto the heart to bypass blocked arteries. It’s like making a detour around a road that’s closed.

But CABG surgery isn’t perfect. Sometimes it’s hard for doctors to find the right kind of blood vessel to use, and the grafts (replacement blood vessels) can fail over time.

Marc Ruel, MD, head of minimally invasive cardiac surgery at the Ottawa Heart Institute, estimates about 80–90 per cent of his CABG patients have ideal vessels for grafting. But for the remaining 10–20 per cent – often older adults or individuals with diabetes – the available vessels are suboptimal, potentially affecting how long the surgical outcome remains effective or successful over time.

At the Heart Institute, Ruel and his team perform about 1,000 CABG procedures annually, meaning 100 to 200 patients may face increased risk due to less-than-ideal grafts.Nationwide, with about 25,000 CABG surgeries performed annually in Canada, this means that between 2,500 and 5,000 patients may undergo surgery using less-than-optimal conduits – highlighting a clear need for innovation in this field.

“These people try to manage their condition with medication or stents,” said Ruel. “But for many, especially those with diabetes, bypass surgery is still the most effective option.”

The risks of CABG extend beyond graft availability.

As Ruel explained, traditional CABG procedures often require “cracking open” the chest through a sternotomy – an incision that splits the breastbone. While newer, minimally invasive techniques aim to avoid this step, sternotomies remain common and are associated with longer recovery times and higher complication rates.

A miniature breakthrough with enormous potential

Their innovation centres on a device no larger than a thumb.

As described in Miniaturized Devices for On-the-Spot Generation of Small-Diameter Vascular Grafts, the nozzle of the device can extrude a synthetic vascular graft from a liquid biopolymer in real time.

As the polymer passes through the nozzle – imagine gelatin squeezing through the tip of a glue gun – it forms a tube with fibres aligned in a circular pattern, closely mimicking the natural structure of blood vessels.

To cure the polymer into a solid tube, the team uses a small optical fibre to shine blue light on the material as it exits the nozzle. It’s like how dentists use a special light to harden a filling, but on a much smaller and more precise scale.

Under the leadership of international visiting student Manuel Calderon, the team also developed a “landing pad” that can attach to the inside of the aorta. This pad could further enable doctors to perform CABG surgery with just a small incision, a technique the Ottawa Heart institute has pioneered on the global scene.

From food truck to the OR

Though the research is still in its early stages, the implications are significant.

Muñoz and his team envision a future where the device is deployed via catheter, like how TAVI (transcatheter aortic valve implantation) transformed valve replacement. Once in place, surgeons in the OR could effectively “print” a new blood vessel directly onto the heart.

For now, the work remains preclinical. The team has tested the nozzle in lab settings, assessing how well the material holds up, how it interacts with blood, and whether it supports the growth of new blood vessels – all with promising results.

The current material – gelatin methacrylate – was chosen for its affordability and responsiveness to light, making it ideal for rapid prototyping. But it’s not the final solution. The team plans to shift toward peptide-based biomaterials that encourage cell growth and long-term integration into the body.

Muñoz and his colleagues in the BEaTS Laboratory believe that with further testing, better materials, and the right support, their device could one day offer a minimally invasive lifeline to patients who currently have no surgical option.