Effects of thymosin β4 on the bone formation of calvarial defects in rats.

Abstract: Purpose: This study aimed to evaluate the effects of thymosin β4 (TB4) on bone formation. Methods: A 5mm diameter bone defect was created in the skulls of Wistar rats. Two types of experimental models were prepared: one with atelocollagen sponges used to fill the bone defect and one without. In each experimental model, bone formation in calvarial defects was compared between the group receiving synthetic partial peptides of TB4 intraperitoneally (TB group) and the control group, which received an equivalent amount of phosphate-buffered saline. Calvarial defect sections collected on postoperative days 5, 10, and 20 were analyzed, and the area of newly formed bone was measured. Furthermore, the sections on postoprerative day 5 were immunostained with anti-osterix antibody and the osterix-positive cells were counted. The total RNA extracted from granulation tissue obtained on postoperative day 10 was analyzed using reverse transcriptase–polymerase chain reaction (RT–PCR). Results: In both models, with or without atelocollagen sponges, new bone formation was significantly greater in the TB4 group than in the control group. In some TB4 group individuals, the entire bone defect region of diameter 5mm was almost covered with newly formed bone by postoperative day 20. Immunostaining revealed a significant number of osterix-positive cells in the TB4 group. On postoperative day 10, the expression levels of bone-related genes were analyzed by RT–PCR, which showed no statistically significant differences between the two groups. Conclusion: The osteogenesis-promoting effects of TB4 observed in critical-sized defects could be of practical use in bone regeneration therapy. [Copyright &y& Elsevier]