Cells have been cultured, or grown, outside the body for many years, but the possibility of growing complex, 3-D tissues – which is literally reproducing the design and function of human tissue – is a recent development. This filed of tissue engineering sounds exciting, but I am going to see what it offers modern medicine. This is the Tissue Engineering Process – from the cell culture and tissue formation in the laboratory to delivery by the surgeon to the patient Potential use of tissue engineering is best seen with chronic leg ulcers Elderly or diabetic patients get sores on their legs that refuse to heal.
These cause constant pain and discomfort. Cause by a failure of natural healing to ‘kick -in’ and natural biological signals that are given off by the body to start healing are missing. We can use tissue engineering to create a ‘living bandage’ This will provide the biological signals needed to start the healing and the healing process gets a ‘jump start.’ Old ladies and men are now happy! 🙂 Sounds easy, but its not! How do you make a tissue – engineered living bandage of skin? Well, the typical elements are one or more types of living cell from a human donor, or the patient himself.
Cells are held on a material support made from a polymer This support will form a structure on which the cells will grow, this will eventually form an ‘engineered tissue’ that the surgeon can use on the patient. For the ulcers I mentioned earlier. It will be something like a simple sheet of tissue. Other requirements such as those for a blood vessel may demand a tube. The engineered product contains several components and requires a manufacturing process that includes the culture of living cells, together with fabrication techniques necessary to produce a 3-D tissue structure.
When damage and then bleeding occurs, the normal healing process takes place in the three following stages: Blood clotting – this happens in minutes. It helps to seal the wound. Platelets, as part of blood clotting, release chemokines, cytokines and growth factors. These chemical messengers in the form of small proteins that are produced by a cell and affect the behavior of other cells. Attract immune cells (within minutes/hours) which help prevent infection in the wound These events, over a longer period of time (hours/days), lead to the formation of new tissues and blood vessels.
In non-healing wounds such as skin ulcers, there is a failure to seal the wound. New blood vessels and tissue do not form and the wound becomes infected easily. The applications of tissue engineering will be far more diverse than has been possible with the non-biological devices. Tissue engineered replacements may ranger from: I. Small Blood vessel replacements II. Bone III. Tendon IV. Ligament and Cartilage repair V. Healing of skin wounds VI. Nerve regeneration (which may help people paralyzed people to walk again, which truly would be a miracle) VII. Repair of problems causing incontinence and impotence VIII. Degenerative problems such as problems in muscle, heart and even the brain.
Picture showing a culture dish containing a square of human skin that has been seeded with epithelial cells, which are forming epidermis. Remarkable new developments in Stem Cell research have helped tissue engineering. What Stem Cells are, are cells in different sorts of tissues of the body. In general, once the cells have become a tissue, they cannot change to become another. E.g. muscle cells cannot become nerve tissues
. However, recent research has shown that even adults contain stem cells, which still manage to retain the ability to form other tissues. It has long been known that cells like these ones could be found in the bone marrow, but, more recently, evidence has come to light that they can be found in other tissues and can even, for example, be harvested from among cells in the fat that is removed during liposuction!