Tissue Engineering is a rapidly growing scientific field focused mainly on developing organ and tissue substitutes by controlling biophysical, biological, and bio mechanical parameters in the lab.
Tissue engineering applies the basic principles and methods of material science, bio engineering, and life sciences towards developing biological substitutes that will maintain, restore or improve tissue functions after being damaged by either diseases or traumatic processes.
Generally, tissue engineering includes combining living cells with a synthetic/natural support or scaffold to come up with a three dimensional tissue that is structurally, functionally, and mechanically similar to or better than the damaged tissue.
The development of such a tissue needs a keen selection of four key elements: scaffold, growth factors, extracellular matrix and cells.
Up to date, Much has been done in the field of tissue engineering, but more work needs to be done in this field.
Steps involved in tissue engineering
Tissue engineering involves various steps, which begin with cell selection, isolation, culturing of primary cells; inducing differentiation to certain phenotype; seeding and cultivating; designing of enough scaffolds, selection of proper materials to be used and how to process them, porosity, inter connectivity, surface characteristics, etc.
The process starts with cell selection
Cell selection is done by extracting solid or liquid tissue.
Fluid tissue, which is blood in most cases, is extracted using centrifugation or apheresis which is easier.
Solid tissue involves more steps, the tissues minced, then trypsin and collagenase enzymes are used to get rid of the extracellular matrix, leaving the cells floating which are also extracted again by centrifugation or apheresis.
Next is Cell isolation and cultivation which is done using the individuals’ autologous cells obtained from the same person’s healthy tissues.
Lately, scientists have been using mesenchymal stem cells from the bone marrow because these cells that can develop into various tissue types.
Other cell types that are used during isolation and cultivation are allogenic (donated from the same species) and heterologous (donated from as different species).
In these cases, sometimes the host’s immune system rejects the cells and there is a possible transmission of diseases from the donor to the host.
In both cases, these are risks that need to be considered.
Then implantation of the extracted cells into artificial structure which can support a three dimensional tissue formation that resembles the extracellular matrix is done
Scaffolds need to meet certain requirements: they should be biocompatible, biodegradable and non-brittle in nature.
The scaffold should also be functionalized with bio molecules while providing nutrients for the cells.
After the tissue is fully developed, its implanted into the living body.
Finally, the tissue is analyzed for performance and compatibility.
Assembly methods in tissue engineering
Tissues are usually assembled in various ways.
Self-assembly – a fabrication technique known as micro masonry is used in self assembling micrometric and sub-micrometric three dimensional units into larger structures – this is the process of encapsulating living cells in polymer cubes.
Liquid-based template assembly – This is whereby a liquid or air surface established by Faraday waves is used as a template for the formation of the three dimensional network.
Additive manufacturing – This is the three dimensional printing of models of organs.
Several layers of living cells are then deposited on a gel medium or a sugar matrix which then slowly develop into three dimensional structures, a good example is when endothelial cells are printed in ring sets and then they are incubated and fused into tubes.
This can be used to grow organs like the liver and kidneys in the near future.
Scaffolding- This is regenerating a similar tissue from a host or a donors’ body
Advantages of Tissue Engineering
– Tissue engineering has very many advantages, from potentially helping people to conquer illnesses and disease or illness to curing extreme and moderate arthritis in patients.
– Tissue engineering also has the ability to prolong our lives by making general quality of our body cells much better.
– Burn victims can also benefit greatly from this venture because tissue engineering can regenerate and restore burned skin.
The restored skin is artificial but very similar to living skin.
By now, scientists are trying to come up with a proper working lung.
But, we lack the proper technology and equipment, but with time, tissue engineers be able to develop any body organs which will one day save millions of lives per year.
Building organs will make organ transplant unnecessary and an individual who needs an organ will not have to be on that organ waiting list waiting for the needed organ.
Disadvantages Tissue Engineering
The disadvantages of tissue engineering are fewer than the advantages.
One disadvantage is the possible existence of hidden diseases in the base tissue.
There is a possibility of transmitting hidden diseases while reconstructing a tissue matter, something that scientists are trying their best to prevent; however, these diseases are not easily noticed with or current technology.
Another disadvantage is a lot of ethical issues
Those who are against tissue engineering are always bringing up these ethical issues.
Hopefully, these issues won’t slow down the growth of tissue engineering.
Tissue engineering has a nice approach of guiding, promoting, and enhancing the ability of tissues to regenerate, assisting to recover functionality and shape of body parts where one cannot heal naturally
In fact, promising advances have been made over the last few years in different area which include bones, heart, cartilage, and pancreas.
Furthermore, Tissue Engineering is transforming how we study human pathophysiology and physiology, resulting to a huge impact on the innovation new therapies.
These 3D models can fill the gap between animal models, 2d models and biomedical research.
But still more research is needed tissue engineering, especially on choosing the material since it appears to the main issue.
More efforts should be geared towards the getting the best out of synthetic scaffolds, because they can be custom made depending on the custom needs and applications.
Tissue Engineering changes very rapidly, so expect more opportunities and solutions from this discipline which surely changes year-by-year.