Temporal and spatial distribution of calcitonin gene related peptide and its receptor in tissue-engineered bone

Abstract

Objective To explore whether the respective implantation of vascular bundles and sensory nerve tracts into a tissue-engineered bone will affect the expression of CGRP (Calcitonin gene related peptide) and its receptor. Methods Fifty-four New Zealand rabbits were randomly divided into 3 even groups for implantation of sensory nerve tracts (group A),implantation of vascular bundles (group B),and a control group of simple tissue-engineered bone (group C) . Animals were sacrificed 4,8,12 weeks after implantation,respectively. Masson staining was conducted to observe the process of bone formation and re-molding. CGRP and CGRPR-1 expressions in the new bone were measured by immunohistochemistry and Real-time PCR at 4,8 and 12 weeks after implantation. Results At all time points,the CGRP and CGRPR-1 expressions in groups A and B were significantly higher than in group C (P<0.05),and those in group A were higher than in group B too (P<0.05) . Over time,the expressions of CGRP and CGRPR-1 mRNA in each group in the new bone tissue were gradually reduced after an initial increase. The neuropeptide expression at the 8th week was higher than those at the 4th and 12th weeks. The neuropeptide expression at the 4th week was the lowest. The expression of CGRP was mainly localized in the periphery of newly generated bone,periosteum and the blood vessels. The expression of CGRPR-1 was mainly localized in the periphery of osteoblasts. Conclusions Implantation of either vascular bundles or sensory nerve tracts can promote neuropeptide secretion. The vascular bundle implantation may result in higher expressions of CGRP and CGRPR-1 than sensory nerve tract implantation. Key words: Tissue engineering; Receptor,calcitonin gene related peptide; Rabbit