There are very few tissues in the body capable of completely regenerating themselves without leaving a scar – the skeleton is one of them. However, the regenerative potential has limitations. Bone loss of more than just a couple centimeters,impacts the body to the point that regeneration cannot occur without treatment using a bone graft and/or bone-growth agents. The best bone graft is recovered from the patients themselves, but this is not possible in most cases. For instance, a soldier who has multiple sites of skeletal damage from an explosion will not have enough healthy bone available for the graft. To help the body heal without using a bone graft, bone morphogenetic proteins (BMPs) have been used. Unfortunately, these powerful agents have known side-effects; including a risk of inducing cancer and causing unwanted bone growth.
The Kacena Lab at the Indiana University School of Medicine is trying a different tactic to help the body heal. We are stimulating a cell found throughout the body, known as a megakaryocyte (MK). These cells make platelets which are widely known for their blood clotting abilities. What is less known about platelets is that they also contain growth factors which set the stage for healing nearly all wounds, including fractures. To stimulate these MK cells we use a growth factor called thrombopoietin (TPO). This is different than using BMPs which primarily stimulate bone forming cells; we are attempting to use TPO to stimulate the activity of MKs that will, in turn, stimulate many cell types in the body that perform many functions. Think of repairing a house after a natural disaster. BMPs focus on rebuilding the walls. But, TPO focuses on more aspects of repair such as removing damaged parts (bone pieces, dead tissue), repairing the plumbing (the blood vessels), and rebuilding the walls.
written by Paul
Carragee EJ, Hurwitz EL, Weiner BK. A critical review of recombinant human bone morphogenetic protein-2 trials in spinal surgery: emerging safety concerns and lessons learned. Spine J. 2011;11(6):471-491.
Carragee EJ, Chu G, Rohatgi R, et al. Cancer risk after use of recombinant bone morphogenetic protein-2 for spinal arthrodesis. J Bone Joint Surg Am. 2013;95(17):1537-1545.
