Bone regeneration by freeze-dried composite of octacalcium phosphate collagen and teriparatide

Octacalcium phosphate collagen composite for periodontal regeneration in a canine one-wall intrabony defect

OBJECTIVE

This study aimed to evaluate the regenerative capacities of octacalcium phosphate collagen composite (OCP/Col) in one-wall intrabony defects in dogs. The background data discuss the present state of the field: No study has assessed the efficacy of OCP/Col for periodontal regeneration therapy despite the fact that OCP/Col has proved to be efficient for bone regeneration.

METHODS

In six beagle dogs, the mandibular left third premolars were extracted 12 weeks before the experimental surgery. Standardized bone defects (5 mm in height and 4 mm in width) were simulated on the distal surface of the second premolars and mesially on the fourth premolars. The defect was filled with either OCP/Col (experimental group) or left empty (control group). Histological and histomorphometric characteristics were compared 8 weeks after surgery.

RESULTS

No infectious or ankylotic complications were detected at any of the tested sites. The experimental group exhibited a significantly greater volume, height, and area of newly formed bone than the control group. The former also showed a greater height of the newly formed cementum than the latter, although the results were not statistically significant. The newly formed periodontal ligaments were inserted into newly formed bone and cementum in the experimental group.

CONCLUSION

OCP/Col demonstrated high efficacy for bone and periodontal tissue regeneration that can be successfully applied for one-wall intrabony defects.

Teriparatide with octacalcium phosphate collagen composite stimulates osteogenic factors

Octacalcium phosphate and collagen composite (OCPcol) promotes osteogenic differentiation and angiogenesis, thereby enhancing bone regeneration. Although a newly developed freeze-dried composite of OCPcol and teriparatide (OCPcolTPTD) reinforced bone regeneration more than OCPcol, the mechanism of bone regeneration remains unresolved. Here, disks containing OCPcolTPTD, OCPcol, or β-tricalcium phosphate (β-TCP) col were inserted into rodents with calvarial bone defects, before euthanasia 4 weeks later. Immunohistochemical and histochemical analyses were performed on bone samples to evaluate bone matrix development, angiogenesis, and osteoclast and osteoblast localization. In the OCPcolTPTD and OCPcol groups, bone regeneration was observed at the surface of calvarial dura mater and around acidophilic granular cells with abundant collagenous fiber-containing cells. Furthermore, the newly formed bone in the OCPcolTPTD group showed a larger total area and individual separated area than the other groups. Various osteogenic proteins were detected in the regenerated bone and peri-bone tissues via histochemistry and immunohistochemistry. Although the expression of several osteogenic biomarkers in the OCPcolTPTD group after 4 weeks of implantation was significantly lower than that in the OCPcol group, new bone formation by OCPcolTPTD in the center of the defect, where bone regeneration is difficult, tended to be superior to that by OCPcol. These results suggest that OCPcolTPTD enhanced bone regeneration more evenly and homogenously than OCPcol.

Segmental Bone Reconstruction by Octacalcium Phosphate Collagen Composites with Teriparatide

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 mm²), followed in order by OCPcol (49.3 ± 21.8 mm²), HAPcol + TPTD (10.6 ± 2.3 mm²), and HAPcol (6.4 ± 2.3 mm²), 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.

New forms of electrospun nanofiber materials for biomedical applications

Over the past two decades, electrospinning has emerged as an enabling nanotechnology to produce nanofiber materials for various biomedical applications. In particular, therapeutic/cellloaded nanofiber scaffolds have been widely examined in drug delivery, wound healing, and tissue repair and regeneration. However, due to the insufficient porosity, small pore size, noninjectability, and inaccurate spatial control in nanofibers of scaffolds, many efforts have been devoted to exploring new forms of nanofiber materials including expanded nanofiber scaffolds, nanofiber aerogels, short nanofibers, and nanofiber microspheres. This short review discusses the preparation and potential biomedical applications of new forms of nanofiber materials.

Octacalcium phosphate collagen composite stimulates the expression and activity of osteogenic factors to promote bone regeneration

Objective

This study investigated the bone regenerative properties of an octacalcium phosphate collagen composite (OCP/Col) in a rat calvarial bone defect model.

Design

An OCP/Col or β‐tricalcium phosphate (β‐TCP)/Col disk was implanted into the critical‐sized calvarial defects and fixed 2 or 4 weeks later. The radiopacity of defects was examined after disk implantation by the radiographic examination and micro‐computed tomography (μ‐CT). Immunohistochemical and histochemical analyses were carried out to assess the bone matrix maturation, neovascularization, and osteoclast and osteoblast distribution in the neonatal bone.

Results

Radiographic and μ‐CT examination of the area of implanted OCP/Col indicated the newly formed bone and no difference from those of the original bone. Osteopontin, osteocalcin, Runt‐related transcription factor 2, type 1 collagen, vascular endothelial growth factor, and alkaline phosphatase or tartrate‐resistant acid phosphatase in the newly formed calvarial bone and the surrounding connective tissue were detected by immunohistochemistry and histochemistry. Biomarker expression was not significantly elevated at the defect site; the area of which was calculated by dividing the distance from the healthy bone margin or calvarium and dura mater surface. There was no difference in the expression of these biomarkers in the OCP/Col group at 2 and 4 weeks after surgery. In addition, the expression levels of all markers were higher in the OCP/Col group than in the β‐TCP/Col group at 2 and 4 weeks after surgery.

Conclusions

The OCP/Col as a bone regeneration material not only exhibits osteoconductive activity that is dependent on residual healthy bone tissue, but also has osteoinductive capacity, which promotes angiogenesis and osteogenic cell invasion from host tissue into the bone defect.