Researchers getting closer to artificial cartilage creation
Researchers at the Case Western Reserve University are one step closer to create implantable replacement cartilage. The method allows cartilage to form from patient’s own stem cells without lengthy culture time before the implantation. The technology could solve cartilage problems which occur after sports injuries and accidents, as well as in cases of osteoarthritis which can occur in ears and noses.
The team placed transforming growth factor beta-1 in biodegradable gelatin microspheres throughout the sheet of stem cells instead soaking the sheet into growth factor. The microspheres provide scaffold-like structure and create space between cells once the gelatin beads degrade. These beads degrade at a controllable rate due to exposure to chemicals released by the cells. As the beads degrade, growth factor is released to cells at the interior and exterior of the sheet, providing more uniform cell differentiation into neocartilage.
The rate of microsphere degradation and, therefore, cell differentiation, can be tailored by the degree to which the microsphere are cross-linked. Within the microspheres, the polymer is connected by a varying number of threads. The more of these cross-links exist, the longer it takes for cell secreted enzymes to enter and break down the material.
The researchers tried with 5 different samples – sparsely cross-linked microspheres containing growth factor, highly cross-linked microspheres containing growth factor, sparsely cross-linked microspheres with no growth factor, highly cross-linked microspheres with no growth factor, and a control sample without microspheres.
After 3 weeks in a petri dish, 4 non-control samples were thicker and more resilient compared to the control sheet. The sheet with sparsely cross-linked microspheres grew into the thickest and most resilient neocartilage, with properties similar to articular cartilage (tough cartilage found in the knee).
Although all 4 samples were thicker and more resilient compared to control sample, achieved properties are still not matching the mechanics of native cartilage. Case Western Reserve University researchers are now working on a variety of ways to optimize the process and make replacement cartilage tough enough for practical application.
Unlike other efforts for artificial cartilage creation, the sheets containing microspheres could be used clinically in just a week of two after the start of culturing. Their strength enables handling during early culturing, thus lowering time and costs compared to cases where cartilage has to be fully grown in the lab before handling. The researchers believe that their finding would perform even better once it is placed in the mechanical environment within the body.
For more information, read the paper published in Journal of Controlled Release named: “Engineered cartilage via self-assembled hMSC sheets with incorporated biodegradable gelatin microspheres releasing transforming growth factor-β1”.