Oral and maxillofacial surgery
Controlled release of platelet growth factors enhances bone regeneration at rabbit calvaria

https://doi.org/10.1016/j.tripleo.2006.11.032Get rights and content

Objective

Platelet-rich plasma (PRP) has been clinically employed to promote bone regeneration. However, few studies have investigated the enhancement of biological function of platelet growth factors after integration of PRP into biomaterials. In this study, the feasibility of gelatin hydrogels for controlled release of platelet growth factors and the consequent enhancement of PRP-induced bone regeneration were evaluated in rabbit calvarial defect.

Study design

Gelatin hydrogels incorporating PRP, PRP-activated thrombin, or an empty gelatin hydrogel were applied to the defect, or the defect was left untreated. Bone regeneration was evaluated by microfocus computed tomography, peripheral quantitative computed tomography, and histological examinations.

Results

Successful bone regeneration was observed at the bone defect applied with the gelatin hydrogel incorporating PRP, which is in marked contrast to other groups.

Conclusion

The gelatin hydrogel is a promising material capable of controlled release of platelet growth factors to enhance bone regeneration.

Section snippets

Preparation of gelatin hydrogels

A gelatin with an IEP of 5.0 was supplied by Nitta Gelatin Co., Osaka, Japan. All chemicals were purchased from Wako Pure Chemical Industries Osaka, Japan and used without further purification.

Gelatin hydrogels were prepared by the glutaraldehyde cross-linking of gelatin as reported previously.12 The water content of gelatin hydrogel (the weight ratio of water present in the hydrogel to the wet hydrogel) was 98 wt%. The resulting freeze-dried gelatin hydrogel was cut into a disk shape (5 mm in

Microfocus computed tomography evaluation

Fig. 2 shows the microfocus computed tomography image of bone defects 8 weeks after treatment with the gelatin hydrogel incorporating PRP or other agents. When the bone defect was treated with the gelatin hydrogel incorporating PRP (Fig. 2, A), complete bone regeneration at the defect was observed. On the other hand, incomplete bone regeneration was observed for the PRP-activated thrombin (Fig. 2, B). No bone regeneration was detected for the empty gelatin hydrogel and the untreated defect (

Discussion

The present study used 5-mm calvaria defects to evaluate bone regeneration in adult rabbits (approximately 20 weeks old). There has been much debate in the literature regarding the appropriate size of the defects for bone regeneration in calvaria models, and defects that do not heal spontaneously have been termed critical size defects. Although the 5-mm defect used in this study is smaller than the critical size defect of 15 mm recommended for rabbits,17 healing was still incomplete without any

Conclusion

For clinical application of platelet growth factors in PRP, one of the important technologies required is the controlled release of growth factors at the necessary site over an extended time period. This study indicates that the gelatin hydrogel is a promising biomaterial for the enhancement of bone regeneration by PRP platelet growth factors.

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