Degenerative joint diseases like arthritis affect millions of people around the world, and range in severity from somewhat annoying to severely debilitating. While scientists have been trying for decades to create cartilage in the lab, it’s proved to be difficult, especially when it comes to the complex, load-bearing cartilage in the knee. So it’s quite a breakthrough that Indian researchers have managed to develop cartilage that is molecularly similar to that in the knee, using 3D bioprinting.
The research team, led by Professor Sourabh Ghosh from the Department of Textile Technology at the Indian Institute of Technology (IIT) Delhi, 3D printed the cartilage using a bioink made up of silk proteins along with cartilage stem cells derived from bone marrow. The chemical composition of the bioink supports both cell growth and long-term cell survival, and has remained physically stable for up to six weeks. The research was published in a study entitled “Elucidating role of silk-gelatin bioink to recapitulate articular cartilage differentiation in 3D bioprinted constructs,” which you can access here.
“This is the first study from India where any 3D bioprinted tissue has been developed in a lab,” said Shikha Chawla, first author of the paper.
“The silk protein has different amino acids that closely resemble the amino acids present in human tissues,” said Ghosh. “Just like cells are surrounded by proteins inside our body, the cells in the engineered cartilage are also surrounded by bioink that has a similar composition.”
The sponge-like, load-bearing cartilage in the knee is called articular cartilage. So far, most cartilage produced in labs has been transient cartilage, which turns into bone cells and becomes brittle, losing its load-bearing abilities. Through bioprinting, however, the bone marrow-derived stem cells in the bioink gradually convert to chondrocyte-like cells, which are specialized cells that produce and maintain the extracellular matrix of cartilage.
“We have succeeded in stopping this conversion of chondrocyte-like cells or stem cells into bone cells so that they remain as stable articular cartilage,” said Ghosh.
The research team was able to do this by optimizing the composition of the bioink as well as the 3D bioprinting process, and by using a combination of growth factors. The silk/gelatin bioink was optimized in a way that activated two signaling pathways that are responsible for minimizing or stopping the conversion of cartilage into bone-like tissue.
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