Induction of insulin-like growth factors expression in dog mandibles by β-TCP

To understand the usefulness of β-TCP for development of biomaterials implants, β-TCP was implanted into bone defects of dog mandibles, and gene expression profiles were examined using DNA microarray. An implant drill was used to make bone defects in Beagle dog mandibles, and then β-TCP was filled into bone defects. Total RNA was isolated from all specimens, and mRNA levels were analyzed using Affymetrix GeneChip. Higher mRNA levels of insulin-like growth factors, IGF1 and IGF2, were observed in β-TCP-implanted samples compared with controls. The enhancement of IGF1 and IGF2 mRNA levels by β-TCP was confirmed by RT-PCR and real-time RT-PCR. Immunohistochemical staining revealed increased IGF1 and IGF2 protein expression in β-TCP-implanted bone. Taken together, the stimulation of IGF1 and IGF2 expression by β-TCP might be a mechanism of accelerating bone formation.