• Question: how does the bone actually repair itself ?

    Asked by cammynkyle to Alastair on 13 Jun 2010 in Categories: .
    • Photo: Alastair Sloan

      Alastair Sloan answered on 13 Jun 2010:

      Good question. It repairs itself because it is not a static tissue, but is continually remodelling itself. Two cell types are always working together to keep breaking down bone and making new bone. Cells called OSTEOBLASTS make bone and cells called OSTEOCLASTS break down bone. When bone in damaged this process is just speeded up and more focussed. After bone is damaged, a large number of immature cells called PROGENITOR cells arrive a the site of damage through the bloodstream or from the bone marrow. They get there by following chemical signals released at the area of damage – a sort of emergency homing beacon. When the progenitor cells get to the site of damage, they specialise and become bone making cells (osteoblasts) or bone breaking cells (osteoclasts). The osteoclasts remove the damaged tissue and the osteoblasts make new bone to replace that which is lost. All this is controlled by bioactive proteins called growth factors and cytokines so that the process is very carefully controlled and monitored. They also make sure that new blood vessels are formed around the new bone so that nutrients from the blood can keep the new bone healthy

Comments

  • Photo: Keith

    Keith commented on :

    I agree with Alastair’s comments. You might also like to know that several diseases affect communication between the cells responsible for bone repair, and have helped us to understand the disease better. One in Paget’s disease, where there is an overgrowth of poorly-structured bone. This illustrates one important way in which we can work out how the body functions normally – by investigating what happen when things go wrong.

  • Photo: Alastair

    Alastair commented on :

    Keith’s right – another good example is good old gum disease, or periodontal disease to give it it’s correct clinical term. People with gum disease can lose their teeth as the bone of teh tooth socket gets eaten away. Why? because the inflammation casued by the infection actually stimulates more of the bone eating cells which breaks down the bone and there are not enough of the bone forming cells to make new bone so the patient loses bone.