Question

Imagine that you are designing a scaffold for cartilage tissue engineering? Describe the requirements of engineered scaffolds for cartilage tissue engineering application. How would you manufacture that desired scaffold? Briefly explain manufacturing method. You will have to use a proper bioreactor system to increase adaptivity of cartilage scaffold to in vivo conditions. Please define what type of bioreactor you need to use. What are the demands that tissue engineering bioreactors have to meet? Would you prefer static or dynamic cell seeding and why?

Answer 1

The requirements of engineered scaffolds must be suitable for cells; they can be synthetic polymeric as well as biological materials. Collagen is one of the biological material with a good tissue compatibility and having less toxicity mainly without any inflammation and also fibrin is one of them with good biocompatibility that can promote adhesion of chondrocytes but because of unstable rate and weak mechanical property its use is limited in tissue engineering. The synthetic materials required were polymer of lactic acid and poly lactic-co-glycolic acid but the comparative one is polycaprolactone (PCL) but even it has an disadvantage that causes inflammation. The required materials can be processed and modified to satisfy the basic requirements.

The manufacturing method for desired scaffold can be conventional method or rapid prototyping (RP) method i.e., auto graft method, that works with availability of donor tissues. The methods include following (a) microscale and macroscale allows fabrication for function of complex tissue. (b) 3D fabrication of vascular beds allows support of   massive complex formation. (c) Followed by 3D techniques of fabrication gives the possible desired scaffolds. The fabrication techniques includes: 1. 3D printing, 2. Electro spinning, 3. Phase separation, 4. Freeze drying, 5.self assembly, 6. Solvent casting, 7. Material injection.

Bioreactor used is spinner flask; its impeller provides a dynamic flow. Also it expands stem cells for cartilage engineering. This flask increases cell proliferation. Other things also includes rocker platform, perfusion across the surface of a construct.

This prefers to  dynamic cell seeding as it drives hydrostatic and osmotic pressures of shear strains.