Advances in technology may soon be able to better heal injuries to the arms and legs that often occur when participating in sports. Researchers have developed 3D-printed artificial tissues that may be more effective in treating injured bone and cartilage in the knees, ankles and elbows, and other sites that are typically damaged in sports-related injuries.
An osteochondral injury is one that damages the smooth surface on the end of bones or the articular cartilage (chondro), and the bone (osteo) that lies beneath it. Articular cartilage is limited in its ability to self-repair, and strategies are needed for the regeneration of damaged cartilage and underlying subchondral bone tissue. New approaches based on suitable scaffolds, made of appropriate engineered biomaterials, have been investigated. These include the combination of biodegradable polymers and bioactive ceramics in various composite structures. A complex process, osteochondral tissue engineering requires overall, a unique composition and organization of the scaffold that combines specific biological properties and mechanical requirements.
Until recently, it has been difficult to reproduce osteochondral tissue in the lab even though recent developments in 3D printing research have led to various scaffold designs and techniques for engineering osteochondral tissue. However, the simultaneous incorporation of multiple types of gradients within the same construct have remained a challenge.
But now scientists have reported their first success in using 3D technology, to engineer scaffolds that replicate the physical characteristics of osteochondral tissue. Bone injuries range widely in scope, from tiny cracks to pieces that will actually break off. In addition to the pain and disability, osteochondral injuries can also lead to subsequent arthritis. The current team has also developed what they believe will eventually be a suitable material for implantation.
“Athletes are disproportionately affected by these injuries, but they can affect everybody,” said the paper’s lead author Sean Bittner, a third-year bioengineering graduate student at Rice University in Houston, Texas, in a statement. “I think this will be a powerful tool to help people with common sports injuries.”
They note that the key to success is the ability to mimic tissue that can gradually transition from chondral tissue at the surface to osteo tissue underneath. The Biomaterials Lab at Rice printed a scaffold using custom mixtures of a polymer for chondral tissue and a ceramic for the osteo tissue that contains imbedded pores to allow the patient’s own cells and blood vessels to infiltrate the implant. This process, if successful, will eventually allow the composite to become part of the natural bone and cartilage.
The final product is a “dual” porosity/ceramic content gradient scaffold that was produced with a multimaterial extrusion 3D printing system for osteochondral tissue engineering. These scaffolds are designed to better address the simultaneous gradients in architecture and mineralization that are part of normal osteochondral tissue, the authors note in their paper.
“For the most part, the composition will be the same from patient to patient,” Bittner said. “There’s porosity included so vasculature can grow in from the native bone. We don’t have to fabricate the blood vessels ourselves.”
Their next steps will involve figuring out how to print an osteochondral implant that will specifically match the patient and one that will also allow the porous implant to grow into and mesh with the bone and cartilage.