Insulin-like growth factor 1 (IGF-1) is already used therapeutically in patients, but not as an aid to fracture repair. Its potential to do this in cases of impaired fracture healing was explored in a mouse model.1 Mice with an induced fracture of the tibia were treated with either IGF-1 alone or IGF-1 plus a transplant of mesenchymal stem cells (MSCs) obtained from bone marrow, or given no treatment.
Mice in both groups showed increased callus volumes compared with controls and there was an increase in new bone at the endosteal and periosteal surfaces. Mice receiving the combination treatment showed a trend towards higher callus volumes and bone deposition, which produced a functional improvement as it enhanced the biomechanical properties of the callus. However, the differences between the groups did not reach significance.
Studies involving histology and in-situ hybridization experiments showed that the increase in callus volume was likely to be due to an acceleration of endochondral ossification.
Editor's comment: The results of MSC transplants on fracture repair have been variable. This study in mice is notable as it explores the delivery of a trophic factor, IGF-1, along with MSCs, which produces a synergistic effect. However, the IGF-1 group alone had a significant response, which begs the question of whether cell therapy will be of additional value. Larger studies to explore this concept are required.
References
- Myers TJ, Yan Y, Granero-Molto F, Weis JA, Longobardi L, Li T et al. Systemically delivered insulin-like growth factor-I enhances mesenchymal stem cell-dependent fracture healing. Growth Factors 2012; e-pub ahead of print 4 May 2012; 10.3109/08977194.2012.683188. [DOI] [PMC free article] [PubMed] [Google Scholar]
