Definition and Requirements for Scaffolds Used in Tissue Engineering

3.1 Definition and Requirements for Scaffolds Used in Tissue Engineering:

A scaffold is an artificial three-dimensional frame structure that serves as a mimic of extracellular matrix for cellular adhesion, migration, proliferation, and tissue regeneration in three dimensions.
An ideal scaffold for tissue engineering should possess the following char-acteristics:
1. It is highly biocompatible and does not elicit an immunological or clinically detectable foreign body reaction.
2. It is three-dimensional and capable of regenerating tissue and organs in their normal physiological shape.
3. It is highly porous with an interconnected pore network available for cell growth and nutrient and metabolic waste transport.
4. It has a suitable surface chemistry allowing for cell attachment, migra-tion, proliferation, and differentiation.
5. It has controllable degradation and resorption rates that match the rate of tissue growth in vitro, ex vivo, and in vivo for biodegradable or resorbable materials.
6. It possesses the appropriate mechanical properties which match those of the normal tissue and organs.
7. It has a bioactive surface to encourage faster regeneration of the tissue.

3. 2 Principles of Scaffold Design:

All tissue and organs in the body are three-dimensional structures. In order to repair and regenerate lost or damaged tissue and organs, three-dimensional scaffolds must be designed, fabricated, and utilized to regenerate the tissue similar in both anatomical structure and function to the original tissue or organ to be replaced or repaired. Therefore, certain principles of scaffold design must be established to ensure proper tissue regeneration.

1- Tensegrity Concept:

Ingber proposed an important principle in scaffold design based on the tensegrity concept. The tensegrity concept sounds new, but it is not a brand new concept because it has been used for centuries in the area of civil engineering. The core of this concept is that mechanical forces are evenly dis-tributed on all regions of the entire scaffold. Therefore, stable structures that can bear forces uniformly, such as triangles, pentagons or hexagons, are pre-ferred structures in a scaffold.