one, the healing process begins. As long as most of the bony substance is not lost, stem cells should be able to make new bone and promote healing. If, however, a significant portion of the broken bone is lost, a large gap may result. This can happen if the bone crumbled, or broke into several pieces and went through the skin.
Under these circumstances, the gap must be filled with matrix, or conductive material, to house stem cells. There are several types of substances that may be used for this purpose.
Bone grafts are often used as matrix material. There are two types of bone grafts.
Autograft. A bone graft can be obtained from the patient. This type of graft is called an autograft. Many different bones can be used to supply the graft. Grafts are most commonly taken from the iliac crest, which is part of the pelvis.
Harvesting a bone graft requires an additional incision during the operation to treat the injury. This makes the surgery take longer and can cause increased pain or risk of infection after the operation. Although autografts have been used with good results, some people may experience pain at the donor site for some time.
Allograft. One alternative to taking the bone graft from the patient is called an allograft, which is cadaver bone. An allograft is typically acquired through a bone bank. Like other organs, bone tissue can be donated upon death.
The use of allografts has grown because it avoids the risk of pain at the donor site. There are risks and benefits for both types of bone grafts, which your surgeon will discuss with you.
Artificial Matrix Material
Man-made materials, such as calcium phosphate, may also be used to fill a large void between bone ends. When treated properly, calcium phosphate can form material that closely resembles bone. It contains holes that are the right size for stem cells to enter and develop into mature cells.
Both calcium phosphate and cadaver bone eliminate the pain and other risks involved with having extra surgery to harvest an autograft.
Growth factors are found inside bone in low concentrations, and in other parts of your body. They can be produced in higher concentrations through genetic engineering.
A lot of work is being done using genetic engineering to help with medical problems. Genetic engineering has made great improvements in making bone heal faster and better.
Genetic engineering can produce large quantities of a needed element in its pure form. During the genetic engineering process, signals inside a cell are altered in order to change the cell's function. To help with bone healing, cells can be turned into factories that produce growth factor proteins.
Growth Factor Proteins and Bone Healing
Growth factor proteins play an important role in the healing process. They call stem cells to the injury site. This is called chemoattraction. The stem cells are drawn to the injured area where they develop into "repair" cells.
Chemoattraction works only when there is a good blood supply around the injured area. If there is not good blood flow, the proteins cannot attract stem cells, or provide them with a way to travel to the area where they are needed.
Bone Morphogenetic Proteins
Many types of proteins aid in bone healing and can be produced with genetic engineering. The most powerful of these are bone morphogenetic proteins (BMPs). These synthetic proteins also help with muscle, tendon, and cartilage healing. Discovered during the 1960s, BMPs today are produced in large enough quantities to effectively speed the healing of damaged bone, especially in fractures that have a difficult time healing.
Of all the types of cells, stem cells have the greatest potential for promoting healing. As discussed above, stem cells are immature cells that are influenced by their surroundings. When brought to an injury site, a stem cell can develop into the kind of cell needed to help in healing - bone, muscle, ligament, and cartilage.
Because of the healing capabilities of stem cells, doctors have developed ways to bring stem cells to an injury site faster and in greater numbers. The fir