Researchers at McGill University developed a tough hydrogel that can resist mechanical forces found in the body. However, the material still provides a friendly environment for encapsulated cells to grow and enables the deep perfusion of blood and other tissue fluids. The injectable biomaterial may be useful in repairing tissues that experience constant mechanical stress, such as the heart, skeletal muscles and vocal cords.
“People recovering from heart damage often face a long and tricky journey. Healing is challenging because of the constant movement tissues must withstand as the heart beats. The same is true for vocal cords. Until now there was no injectable material strong enough for the job,” said Guangyu Bao, one of the lead developers of the new material, in a McGill announcement. “The results are promising, and we hope that one day the new hydrogel will be used as an implant to restore the voice of people with damaged vocal cords, for example laryngeal cancer survivors.”
Injectable biomaterials are at the forefront of regenerative medicine, with the potential for minimally invasive delivery through a needle, and regenerative efficacy that is achieved with encapsulated cells, drugs, or growth factors. A key factor in the design and performance of such materials is their porosity. High porosity allows blood to permeate the material, keeping encapsulated cells alive, and allows secreted or loaded growth factors or drugs to escape the gel and mediate therapeutic effects in surrounding tissues.
However, high porosity can impact the mechanical strength of the biomaterial, meaning it does not last for extended periods within the target tissues. This is a big challenge in particularly dynamic tissues, such as muscle or vocal cords, where constant movement contributes to stresses and wear that cause the biomaterial bolus to degrade.
This newest hydrogel injectable contains a double-network of crosslinked fibers, which is essentially two intertwined interpenetrating networks that help to increase the gel strength but maintain the required porosity for regenerative medical applications.
To test the strength of the material, the researchers placed it in a device designed to mimic the biomechanical forces experienced by the vocal cords during speech. The device vibrated at 120 times a second for over six million cycles, and the gel material was still largely intact afterwards, whereas other gel formulations were destroyed by the mechanical disruption.
“We were incredibly excited to see it worked perfectly in our test. Before our work, no injectable hydrogels possessed both high porosity and toughness at the same time. To solve this issue, we introduced a pore-forming polymer to our formula,” said Guangyu Bao.
“Our work highlights the synergy of materials science, mechanical engineering and bioengineering in creating novel biomaterials with unprecedented performance. We are looking forward to translating them into the clinic,” added Professor Jianyu Li, another researcher involved in the study.
See a video demonstration of the mechanical testing rig below.
Via: McGill University