Analysis of rat calvaria defects implanted with a platelet-rich plasma preparation: Histologic and histometric observations

Objectives: It has been suggested that degranulating platelet α-granules release growth factors having a potential to modulate bone formation. The objective of this study was to evaluate the osteoconductive potential of a platelet-rich plasma (PRP) preparation. Methods: Thirty adult male Sprague-Dawley rats were used. The PRP preparation was obtained from 10 ml of whole blood drawn from one age-matched donor rat. The preparation was processed by gradient density centrifugation and stored at -80°C until use. Using aseptic techniques, the PRP preparation soak loaded onto an absorbable collagen sponge (ACS) or ACS alone was surgically implanted into contralateral critical size 6-mm calvaria osteotomies in 18 animals. Twelve animals received ACS versus sham surgery in contralateral defects. Animals were sacrificed at 4 and 8 weeks when biopsies were collected for histologic and histometric analysis. Results: The animals were maintained without adverse events. Bone formation was highly variable in sites receiving PRP and control treatments. Defect bone fill at 4 weeks averaged (± SD) 28.8 ± 27.4% (PRP/ACS) versus 39.1 ± 24.4% (ACS; p = 0.2626) and 62.0 ± 20.0% (ACS) versus 71.6 ± 32.2% (sham surgery; p = 0.1088), and at 8 weeks 81.0 ± 12.9% (PRP/ACS) versus 64.5 ± 28.1% (ACS; p = 0.2626) and 75.6 ± 34.1% (ACS) versus 74.1 ± 24.2% (sham surgery; p = 0.7353). Remnants of the ACS biomaterial were observed at both 4 and 8 weeks in sites implanted with PRP/ACS or ACS. Conclusions: The results suggest that the PRP preparation has a limited potential to promote local bone formation.