Applications of Exogenous Mesenchymal Stem Cells and Low Intensity Pulsed Ultrasound Enhance Fracture Healing in Rat Model

The present study aimed to investigate the effects of combined treatment of exogenous mesenchymal stem cells (MSCs) and low intensity pulsed ultrasound (LIPUS) on fracture healing by comparing LIPUS-MSC, MSC and control (CTL) groups. Radiography and quantitative callus width/area demonstrated that the MSC-LIPUS group had the best healing, MSC group the second and CTL group the poorest with significant differences among each at different time points. Micro-CT data supported that MSC-LIPUS had the highest bone volume/tissue volume. Histomorphometry showed a significantly faster remodeling in late phase in MSC-LIPUS and MSC groups. These indicated that the combined treatment of MSCs and LIPUS was beneficial to fracture healing. Regenerative power and homing ability of MSCs were shown by promotion in fracture healing and locally found green fluorescent protein (GFP)-labeled MSCs at fracture calluses. This evidence reflects that co-treatment of MSCs and LIPUS may be developed as an intervention for delayed union or nonunion.