Cartilage is a firm nonvascular tissue found in the joints between bones, between the spinal vertebrae, in the ears and nose, and in the bronchial tubes in air ways. Hyaline cartilage is found between the joints and is designed to distribute the load evenly. Chondrocytes are responsible for the production of cartilage as well as other extra cellular matrix components. Due to the lack of the vasculature cartilage has very low regenerative capability. The ability to print chondrocytes and introduce the scaffold into an injured area can help with the regeneration of cartilage. The aim of this project is to design and print a scaffold seeded with mesenchymal stem cells that could potentially be differentiated into chondrocytes.
The chosen bioink will also be printed and undergo rheological testing to determine the physical properties. Finally, the chosen bioink will be seeded with mesenchymal stem cells to determine the viability of the cells after printing. This projected will be limited to computer modelling and in vitro experiments. In vivo testing will not be done for this project.
Objectives
- To develop a cost effective bioink
- To determine rheology and printability
- To mimic the components of native cartilage (mainly collagen and proteoglycans) as best possible
- To verify the biocompatibility of bioink
- To prototype a combination of bioink and scaffold
- To test the elasticity of scaffold
- To analyze the changes in scaffold’s viscosity under shear strain
- To observe cell adhesion, growth, proliferation via electron microscopy
Recommendations
In future work, more testing trails could be done in rheological analysis. CCK-8 kits would help to determine the number of cells for proliferation assay [14]. With the conditions permits, swelling ratio, porosity, degradation, and cellular inoculation efficiency should be observed. To control cell differentiation, add growth factor (such as TGF-β3) in MSC cells seeding, or use chondrocytes cells directly. A longer culture of the constructs provides more information reflecting the condition of cell growth. A computer model and physical model will both be created. Using the custom material feature of Siemens NX, a finite element analysis can be done on the chosen material to determine the theoretical physical properties of the scaffold.
There are many interesting aspects to explore the potential of gelatin-based bio-ink. First, attempting various method of seeding cells will make the difference. For example, doping a cell suspension to aggregate cells [10] for culturing avoids pressure limitation in scaffold printing process. The accuracy of scaffold printing could be enhanced without considering cell viability during printing process. Besides that, the shape of the extrusion needle also affects the cell viability. [41] At low printing speed, coaxial shape has a great performance compared with other shape. In addition, a rounded pores in scaffold are better than the typical lattice pattern in bioprinting. [42] [10] Overall, gelatin has great potential to promote 3d bioprinting when it combined with other techniques.
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