CH391L/S13/Cell Scaffolding and Printing

Cell Scaffolding

Cellular scaffolding is used in biomedical engineering to support tissue growth, usually during the process of tissue regeneration or tissue engineering. There are several requirements that the scaffold needs to fulfill in order to be a good support for cells and tissues.

1) The cells need to be able to be placed precisely onto the scaffold. Tissue-specific stem cells need to be placed in the right location onto or into a scaffold or else the cells may develop abnormally.[1] The cells also need to be able to adhere to the scaffold through secretion of extra cellular matrix (ECM) proteins and saccharides.[2]

2) The cells need to be able to survive on the scaffold (the scaffold should be biocompatible). This includes that the scaffold should be able to facilitate cellular signaling by signaling molecules or mechanical ques. One challenge faced by tissue engineers is the lack of known biocompatible scaffolding material with the particular properties needed in applications such as tissue printing and rapid prototyping techniques.[2]

3) The scaffold needs to be rigid enough to support tissues, but porous enough to diffuse oxygen and nutrients to the cells inside. If the scaffold is poorly designed, it could collapse or starve the cells growing inside the scaffold.[2][1]

4) The scaffold should be able to guide the development of new tissues. (Read the Tamjid and solorio papers)

Scaffold Fabrication Methods

These methods for scaffold construction are just a few of the many techniques used in tissue engineering. Other techniques in use but not discussed include: phase-separation,freeze dry and self-assembly scaffold construction.

Electrospinning

An artful picture of electrospinning. Picture taken from www.plantandfood.co

In this process, high voltage is applied to a capillary tube filled with a polymer solution. The polymer is repulsed by the electric field and when the field is intense enough, the polymer solution flies out the end. The solvent evaporates and the polymer hardens into a tangled web. The diameter of the threads can be adjusted anywhere from the nanometer to micrometer range. (Sill paper and Lu paper)

This process is easy and simple and the resulting topography is similar to the ECM. It widely used to engineer scaffolding for tubular tissues, like vascular or urethral, and other tissues. (Sill paper and Lu paper)

This diagram depicts the process of electrospinning [3]

A picture of the end result [4]

iGEM Connection

References

<biblio>

1. jinlee pmid=23355718
2. Derby pmid=23161993
3. Lu pmid=23345979
4. Jirsak Jirsak O. et al.: Polyamic Acid Nanofibers Produced by Needleless Electrospinning. Journal of Nanomaterials, Article ID 842831, 6 pp. (2010)