Where does engineered tissue come from?
Engineered tissue is formed by the use of a scaffold (natural or a biodegradable synthetic structure) that usually has human cells implanted prior to the implantation of the scaffold in the patient. The source of cells varies, but the preferred sources are cells derived from the patient (such as bone marrow or muscle biopsy) to avoid any immune response issues by using the patient’s own cells.
What are the potential uses of engineered tissue?
Engineered tissues can in principle replace any hard (cartilage/bone) or soft tissue (skin/veins/arteries/organs) that may be damaged by disease or injury. Note: not all applications have been investigated in the laboratory and the clinically available tissue engineered systems are perhaps limited to about 25 different procedures.
What diseases can be cured by using engineered tissue ?
Tissue engineering can be applied clinically where the natural tissue has been damaged or destroyed.
In the future, it MAY be possible to engineer replacements for any tissue; at this time, the
procedures that are clinically available include:
- Orthopaedic surgery, abdominal surgery
and gastrointestinal surgery.
Are engineered tissues currently used in therapies today?
Tissue engineering is used extensively in clinical procedures today. Probably the world's most
successful tissue engineering work is based on the findings of Dr. Stephen Badylak. He demonstrated
that submucosa derived from porcine small intestine or urinary bladder can be the source of scaffold
material. Over 500,000 patients have been treated with this technology. Other engineered tissues are
being used on an experimental basis; an example is the work of Dr. Anthony Atala who is using engineered
tissues to build bladders for patients who are afflicted with spina bifida.
Can any type of tissue be engineered?
In principle, yes any type of tissue can be engineered. However, one needs to recognize that different tissues have different attributes. As an example, cardiac tissue needs to contract (beat). In this area, there is a team that is led by Dr. William Wagner that is developing a tissue engineered cardiac patch. This is still a laboratory study and would not be available for clinical trials for at least 5 years.
What are scaffolds?
In the context of engineered tissue, a scaffold is a material that can be formed in the shape of tissue that needs to be replaced (as an example a rotator cuff). The scaffold can be biologically derived or a synthesized material. The scaffold material must be biologically compatible for human implantation. The scaffold is typically impregnated (seeded) with a patient’s cells before implantation. Finally the scaffold must be designed to “dissolve” as the cells grow on the scaffold. Typically, in several months, the scaffold has disappeared and has been replaced by new tissue.
What is the difference between engineered tissue and skin from a skin bank?
Skin Banking is a process in which skin is removed from a donor body, tested for suitability as a graft material, packaged, stored, and finally reused as a graft. The process is similar to that for blood banking. Skin grafts can be autografts or allografts.
An autograft is tissue which is remove from and then re-used on the same individual. Auto-skin grafts can be used as a treatment for 2nd and 3rd degree burns and for reconstructive surgery. Skin autografts are permanent replacement grafts and will heal full thickness burn wounds.
Allografts are tissue that is removed from one individual and used on a different individual. Allograft skin is used as a temporary burn wound graft and will be rejected by the recipient, usually within 7-21 days. Until rejection, however, allograft skin will provide many of the functions of healthy skin. Skin allografts will close a wound providing a barrier against infection and fluid loss, decrease pain, and promote healing of underlying tissues. Skin allografts are use as a transitional treatment until autografting can permanently close the burn wound.
What kinds of research have been done with engineered tissue and what still needs to be done?
Tissue engineering is in its infancy. While certain clinical procedures routinely use tissue engineering (an example is rotator cuff repair), there is still a lot of fundamental research in the design of scaffolds that must be followed by extensive clinical trials. This is a rapidly changing scene, so the opportunities for the use of tissue engineering will surely change year-by-year.