Tissue Engineered Bone
Bone tissue engineering is still in the experimental stages. Scientists are experimenting with different methods of bone tissue engineering to find a suitable and successful method to grow replacement bone. Tissue engineered bone will be beneficial to patients with degenerated bones and bones damaged by trauma. Tissue engineered bone will be superior to current surgical methods, which use bone grafts that often fail.
Bone grafts can be obtained from cadaver bone, which requires the patient to be put on immunosuppressive drugs. Bone grafts can also be obtained from healthy bone in the patient that needs the bone graft. This method subjects the patient to a painful surgery and trauma to healthy bone. Man-made materials are sometimes used to replace or repair damaged bone, but these can fail due to stress and do not regenerate like normal bone does.
Tissue engineered bone will function the same as normal healthy bone and will regenerate the same as normal healthy bone does.
Mesenchymal Stem Cells in Bone Tissue Engineering
Stem cells can be harvested from a patient, programmed to grow into bone cells, and expanded in a culture before being injected back into the patient to encourage bone regeneration. The more popular method is to grow the expanded stem cells on a scaffold where they can form into bone before they are surgically implanted into the patient.
The use of mesenchymal stem cells has produced promising results in the laboratory setting. Mesenchymal stem cells, obtained from bone marrow, can be engineered into bone. Bone marrow is not the only place that mesenchymal cells can be found, but bone marrow contains an abundant amount of mesenchymal stem cells. Mesenchymal stem cells easily convert to osteoblasts, the cells that create bone formation. Mesenchymal stem cells are harvested from a patient in a fairly simple and quick procedure done under general anesthesia which does not require a long recovery time. Stem cells used in this way are called autologous, meaning the cells are harvested from the same patient on whom they will be used.
Mesenchymal stem cells are seeded into a biodegradable porous scaffold built in the shape of the desired replacement bone. Growth stimulating substances are added to the cells to encourage bone tissue growth. The mesenchymal stem cells expand and grow into healthy bone tissue and are implanted into the patient.
Some scientists have conducted research that has shown that increased bone formation from the mesenchymal cells can be obtained by adding the growth stimulators before the cells are seeded into the scaffold. The growth stimulators are removed before the cells are seeded onto the scaffold. Not only did research show this method increased bone formation, it brought the hormone levels in the tissue engineered bone down to the normal hormone levels found in natural bone by the time the bone was implanted.
Synthetic Oxygen Carriers
Lack of oxygen supply has been an obstacle in growing engineered tissue in the laboratory. Lack of oxygen to the growing bone cells causes some of the cells to die. Nadav Kimelman, at the Hebrew University of Jerusalem’s Faculty of Dental Medicine, has come up with a method to increase oxygen supply to encourage increased and faster bone growth. Kimelman injected synthetic oxygen carriers into the scaffold, which successfully increased the speed and amount of growth of the tissue engineered bone.