Single-dose local administration of parathyroid hormone (1-34, PTH) with -tricalcium phosphate/collagen (-TCP/COL) enhances bone defect healing in ovariectomized rats

Parathyroid hormone (1-34, PTH) combined -tricalcium phosphate (-TCP) achieves stable bone regeneration without cell transplantation in previous studies. Recently, with the development of tissue engineering slow release technology, PTH used locally to promote bone defect healing become possible. This study by virtue of collagen with a combination of drugs and has a slow release properties, and investigated bone regeneration by -TCP/collagen (-TCP/COL) with the single local administration of PTH. After the creation of a rodent critical-sized femoral metaphyseal bone defect, -TCP/COL was prepared by mixing sieved granules of -TCP and atelocollagen for medical use, then -TCP/COL with dripped PTH solution (1.0 mu g) was implanted into the defect of OVX rats until death at 4 and 8weeks. The defected area in distal femurs of rats was harvested for evaluation by histology, micro-CT, and biomechanics. The results of our study show that single-dose local administration of PTH combined local usage of -TCP/COL can increase the healing of defects in OVX rats. Furthermore, treatments with single-dose local administration of PTH and -TCP/COL showed a stronger effect on accelerating the local bone formation than -TCP/COL used alone. The results from our study demonstrate that combination of single-dose local administration of PTH and -TCP/COL had an additive effect on local bone formation in osteoporosis rats.