Genetically Modified Mesenchymal Stem Cells Promote Spinal Fusion through Polarized Macrophages

MSCs were genetically modified to overexpress placental growth factor, and its effects on macrophage proliferation and polarization were analyzed in vitro in a transwell co-culture system, as well as in vivo in a mouse model for spinal fusion, for which the cells were bilaterally injected into paravertebral muscles of the mouse lumbar spine.