New Biomaterial for Preventing Uncontrolled Bleeding

Image highlighting the injectability of the biomaterial through a catheter. The biomaterial can maintain its shape upon injection, only becoming liquid after a force is applied. Inset is a zoomed image of the STB extruded from the catheter tip.

To treat an aneurysm, gastrointestinal bleeding or other forms of uncontrolled hemorrhaging, clinicians often use tiny metallic coils, which can be permanently inserted into a blood vessel to prevent further bleeding. But such coils come with limitations. Patients on blood thinning medications or who cannot form blood clots for other reasons can experience dangerous break-through bleeding, with rebleeding occurring in as many as 47 percent of patients. To find a better solution, bioengineers from Brigham and Women’s Hospital, led by Ali Khademhosseini, PhD, collaborated with Rahmi Oklu MD, PhD, FSIR, a clinician who is an interventional radiologist (previously at Massachusetts General Hospital, now at Mayo Clinic). Khademhosseini and Oklu’s team develop a rapidly deployable hydrogel that can hold its shape within a blood vessel to prevent bleeding, even in those who cannot form blood clots. The newly developed agent is described in a paper published in Science Translational Medicine Nov. 16.

“This work is an example of how bioengineering can help address the challenges that clinicians and patients face,” said Khademhosseini. “Our work thus far has been in the lab, but we are on a translational path to bring this new biomaterial for embolization to the clinic to improve patient care.”

The new agent, known as a shear-thinning biomaterial (STB), has a consistency similar to toothpaste and is made up of both gelatin – which gives it gel like properties – and nanoparticles. Using a catheter, the material can be flowed into a blood vessel but is able to maintain its shape once inside the vessel, obstructing the vessel or aneurysm without relying on the formation of a blood clot. Mechanical testing in the lab was initially performed and monitored the STB’s changes over time to optimize the material’s properties in animal models. The team then tested the STB in both rodent and porcine models, the latter of which have blood vessels of similar dimensions to human blood vessels.

Some of the beneficial properties of the STB include its ability to withstand pressure within the blood vessel, remain at the site of injection and naturally degrade over time. In addition, the team found that the material attracted cells to migrate and deposit themselves at the site of the STB, helping to block the vessel. The individual component materials that make up the STB have been previously used in humans making their subsequent regulatory process and clinical use easier.

As a next step, the team hopes to begin clinical trials to test the safety and efficacy of the STB for use in humans.