Bio 3D printing technology is highly competitive globally. A team of Indian researchers from Indian Institute of Technology (IIT) Delhi and Indian Institute of Technology Kanpur recently made a breakthrough in 3D printing of cartilage, which was then generated by adding thyroid hormones to the bones. This discovery will accelerate the development of bioprinting technology and technology.
There are two ways to form bones. For non-load bearing bones like skulls, mesenchymal stem cells differentiate directly into bone cells. For load-bearing bones such as the femur, stem cells first differentiate into cartilage templates and then undergo more differentiation into osteoblasts over time. So far, attempts to create load-bearing bone using stents have directly differentiated stem cells into bone cells, skipping the naturally occurring cartilage phase in our body. "The efficacy of this skeletal structure has not been confirmed in bearing loads. There is a very poor correlation between bone constructs developed in vitro and in vivo. In addition, the gene expression patterns of these tissue engineered bones are quite different from those of human adults. Professor Sourabh Ghosh of IIT Delhi Textile Technology Department commented.
The team decided to mimic the cartilage step with a 3D bioprinted cartilage scaffold and then treated the cartilage scaffold with thyroid hormone (triiodothyronine or T3) to stimulate the cartilage to differentiate into bone-like cells. Their 3D printed bones show genes and proteins that are similar in expression to genes and proteins found in naturally occurring bone, and the essential cellular signaling pathways for osteogenic differentiation are also upregulated. “When we use different strategies to develop bones, the similarities in limb skeletal development are higher,” Professor Ghosh said.
Cartilage scaffolds provide a suitable substrate for substances that will become the extracellular matrix of bone. Professor Amitabha Bandyopadhyay from IIT's Department of Biological Sciences and Bioengineering in Kanpur explained that “the weight-bearing capacity of bone depends mainly on the quality of the extracellular matrix. In stressed bone, extracellular matrix accounts for 95%, while bone cells account for only 5%. Therefore, if you are trying to create a load-bearing skeletal structure, it is better to have more extracellular matrix. The extracellular matrix of the bone construct formed by the intermediate cartilage process is 10 times higher than the bone formed directly from the stem cells. ”
Stem cells and cartilage take about three weeks to develop, and the cartilage to bone step takes two weeks. Although the study did not study the mechanical properties of 3D printed bones, Professor Ghosh said that their initial tests showed that it was stronger than bones that differentiated directly from stem cells.