Tissue Engineering

1) What is tissue engineering and how does it impact on the society?

Tissue engineering is a multidisciplinary field that focuses on the design and manufacturing of a group of cells that work together to perform a controlled and directed function using physical, biological, chemical and engineering processes. Tissue engineering impacts society by potentially allowing for a novel method for tissue regeneration to be utilized in medical settings. Currently, there is a shortage of organs/tissues available for transplant, and tissue engineering has the potential to alleviate this burden on medical services by providing tissues/organs as they are required.

2) As a multi-disciplinary field, how does the life sciences and engineering interact in tissue engineering? Please give a detail explanation and examples.

Tissue engineering is the use of cells, materials, engineering methods, and suitable biochemical and physicochemical factors to improve or replace biological tissues. As tissues requires certain mechanical and structural properties to ensure that the function properly, the use of scaffolding for the formation of new viable tissue for medical purpose is an example of how life sciences and engineering interact in the field of tissue engineering. As cells are the building blocks of tissues, understanding how individual/ groups of cells respond to signals, interact with their environment/ extra cellular matrix, and organize into tissues and organisms requires tissue engineering to have a life science focus so that researchers can manipulate these processes to regenerate damaged tissues or create new ones. In order to engineer tissues, cells need a physical construct on which they can grow in a three-dimensional shape and this structure is the tissue scaffold. The scaffold needs to be made from materials that promote cell adhesion, proliferation and growth and in addition, these scaffolds need to be constructed in an orientation that provides the correct physical/mechanical stimuli to the cells that allows them to develop into the desired tissues. The development of these scaffolding in terms of which materials are biocompatible, if the scaffolding adheres to the biophysical conditions required for the cell growth as well as the manufacturing process of the scaffolds are the reason as to why engineering is required in the tissue engineering field. As a result, life sciences and engineering interact in the fields of tissue engineering by understanding what are and how the cellular processes required to create these tissues work whilst understanding which materials can be used and how they can be manipulated to facilitate the generation of tissues constructs.

3) In an attempt to build a tissue for incorporation into a host body, what major obstacles must be overcome? List and describe some of these obstacles in terms of the biological, biophysics and biomaterials considerations.

In order to build tissue for incorporation into a host body, various obstacles should be considered and overcame. These obstacles include biological ones which arise when ensuring that the cells that are being used as materials are able to grow and develop into the desired tissue. As a result, it should be ensured that the seeding cells are the correct type of cell that will proliferate and differentiate into the desired tissue type. In addition, adequate growth factor and scaffolding should be used to allow for the proliferation of the cells. One challenge for tissue engineering arises due to cell’s requirement for growth factor. Growth factor for the use in tissue constructs implanted into humans has not been by the FDA as it has not been proven that the growth factors will not cause the development of cancer. This is because, once the growth factor is introduced, into the human recipient, there is no mechanism to ensure the growth factor is only effective on the implanted tissue construct while the cells require it for growth, and will not affect the surrounding healthy tissue.

Tissues are complex structures that require cells to differentiate into different cell types cells with a specific function that work together to develop a functional tissue. These cues often come from the ECM and surrounding environment. As a result, another major biological obstacle that should be overcome is understanding all the physical, mechanical, electrical and chemical cues that a cells needs for migration, cell differentiation, proliferate etc. In addition, we need to understand how, when and in what proportions these cues come into play. Furthermore, attempting to build tissues introduces biophysical issues that need to be addressed. The tissue that is being formed must be able to correctly interpret and withstand the physical stresses being placed on the tissue in vivo. In terms of biomaterial considerations, the biomaterial must be dissolvable in vivo, non toxic and absorbable. In addition, the biomaterial should promote cell adhesion and growth.

4) List three application examples for each of the following, and comment on the advantages, disadvantages or limitations.

Autografting is the process of obtaining natural tissue from the patient and using it to rebuild physical structures and then transplanting it onto another location on the same patient where it is required. Examples of this process include skin or bone grafts and fat transfer. The main advantage of autografting is that there