Fixing Cartilage with 3D Printing and Stem Cells

The quest to mend damaged cartilage has led scientists to explore the power of 3D printing and stem cells. This isn't just about printing ink on paper. It's about using a special kind of ink made from natural materials and living cells. The goal is to repair cartilage, the smooth, white tissue that covers the ends of bones in joints. When this tissue gets damaged, it can lead to pain and stiffness, making simple movements difficult. To tackle this, researchers turned to embryonic-derived mesenchymal stem cells, or ES-MSCs. These are special cells that can turn into different types of cells, including those that make up cartilage. They mixed these cells with a bioink made from fibrin, a protein involved in blood clotting. This bioink can be printed using a special 3D printer. The printer scans the surface of the damaged cartilage and prints the bioink directly into the defect. This process is called in situ bioprinting. The researchers used a fancy bioprinting system with multiple tools and six axes of movement. This allowed them to precisely map and print within the cartilage defects. They tested different bioink formulations, including one with nanocellulose and another with nanocellulose and hyaluronic acid. These additions improved the print quality and helped the cells grow into cartilage-like tissue. After printing, the bioink gels were hardened and cultured in a special medium for up to eight weeks. The researchers checked the printed constructs for cell survival, strength, and the presence of cartilage-specific genes and proteins. They found that the printed constructs got stronger over time, with mechanical properties improving from 30 to 50 kPa after three weeks to about 150 kPa after eight weeks. The cells also showed signs of turning into cartilage cells, with increased expression of chondrogenic genes and positive staining for cartilage-specific markers. This research shows that it's possible to combine stem cells with printable bioinks and a advanced bioprinting system to repair cartilage damage. However, there's still a long way to go before this technology can be used in humans. More research is needed to ensure the safety and effectiveness of this approach. But the potential is there, and it's an exciting area of research in the field of regenerative medicine.