A hydrogel that firmly adheres to cartilage and meniscus

EPFL researchers have developed a hydrogel, composed of nearly 90% water, which naturally adheres to soft tissues such as cartilage and meniscus. If the hydrogel carries repair cells, it could help heal the damaged tissue.

Some types of body tissues, such as cartilage and meniscus, have little or no blood supply and are unable to heal if they are damaged. A promising solution to this problem is to inject a hydrogel loaded with repair cells or drugs into the damaged area in the hope of stimulating tissue regeneration.

However, commercial hydrogels do not remain put after being applied to the area to be treated because of the pressure exerted by body movements and the flow of body fluids. Doctors therefore use special membranes to hold the hydrogel in place, but these membranes are secured using sutures that perforate the very tissue that the hydrogel is supposed to heal.

Two EPFL research groups, led by Dominique Pioletti and Pierre-Etienne Bourban, created a biocompatible hydrogel that adheres naturally to soft tissues such as cartilage and meniscus. Their hydrogel, composed of nearly 90% water, can withstand mechanical stresses and significant deformation, eliminating the need for a separate binding process. Their research was published in Applied materials and interfaces ACS.

"Our hydrogel is ten times more adhesive than the bioadhesives currently available on the market, such as fibrin," says Pioletti, head of the biomechanical orthopedics laboratory at the School of Engineers. EPFL. "And thanks to its high water content, our hydrogel is very similar in nature to the natural tissue that it is designed to cure."

Dual network composite hydrogel

The new hydrogel is actually a composite material consisting of a dual array matrix and a fiber optic network. This structure preserves the strong adhesive capacity of the material by mitigating the impact of mechanical stresses. "The dual-network structure distributes the mechanical energy entering the hydrogel, so the material shows an improvement in adhesion when it is compressed or stretched," Pioletti explains. "In hydrogels lacking these damping mechanisms, mechanical stresses focus on the interface between the hydrogel and the tissue and the hydrogel dissipates quite easily."

Co-author of the article, Martin Broome, who heads the Department of Oral and Maxillofacial Surgery at the University Hospital Lausanne (CHUV), is convinced that this type of hydrogel could make a real difference. "If we rely on the outstanding adhesive properties of the hydrogel, this could open the door to a large number of potential applications.One day, for example, it could be used instead of metallic materials like the titanium to fix bone fractures, may no longer need to use complex sutures on some types of soft tissue. "

In its current form, the hydrogel developed at EPFL can adhere to several tissue types. The next step for researchers will be to adapt it to specific applications. "Now that our material has demonstrated superior mechanical properties, we will be working on loading with different agents that could help heal the patient's cartilage or meniscus," Pioletti concludes.

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More information:
Peyman Karami et al. Dual-network composite hydrogels to improve adhesion to biological surfaces, Applied materials and interfaces ACS (2018). DOI: 10.1021 / acsami.8b10735