Segmental Bone Reconstruction by Octacalcium Phosphate Collagen Composites with Teriparatide

Impact statement Octacalcium phosphate and collagen composite (OCPcol) is a bone regenerative material that has been recently commercialized in Japan. Teriparatide (TPTD) is a recombinant form of parathyroid hormone, and is used for the treatment of osteoporosis. It was investigated whether single-dose local administration of OCPcol with TPTD can repair a canine segmental bone defect, which was supposed to be an intractable bone defect. Compared with OCPcol, hydroxyapatite, and collagen composite (HAPcol) with TPTD, or HAPcol, because OCPcol with TPTD quickly enhanced bone regeneration and bridged the defect, it would be a candidate for the repair of intractable bone defect. Octacalcium phosphate and collagen composite (OCPcol) demonstrated superior bone regeneration and has been commercialized recently in Japan. Teriparatide (TPTD) is a bioactive recombinant form of parathyroid hormone that is approved for osteoporosis treatment. Because mandibular bone reconstruction after segmental resection is a key clinical problem, it was examined whether single-dose local administration of OCPcol with TPTD can affect recovery after this procedure. OCPcol was prepared, and a commercially available hydroxyapatite and collagen composite (HAPcol) was used as a control. A 15 mm length segmental bone defect was made in the mandibular region of male beagle dogs. The experimental animals were divided in four groups. OCPcol treated with TPTD (OCPcol + TPTD), OCPcol, HAPcol treated with TPTD (HAPcol + TPTD), or HAPcol was implanted into the defect. The radiopaque areas of the implanted site were measured and statistically analyzed, and histological examination was performed after 6 months. The value of radiopaque area in total region of OCPcol + TPTD was highest (90.8 +/- 7.3 mm(2)), followed in order by OCPcol (49.3 +/- 21.8 mm(2)), HAPcol + TPTD (10.6 +/- 2.3 mm(2)), and HAPcol (6.4 +/- 2.3 mm(2)), and that of OCPcol + TPTD was significantly higher than that of HAPcol + TPTD or HAPcol. All segmented mandibles of OCPcol + TPTD and a part of those of OCPcol were bridged with newly formed bone, whereas no bone bridges were observed in HAPcol + TPTD or HAPcol. These results suggested that OCPcol treated with TPTD enabled bone reconstruction after segmental mandibular resection more than other three groups.