| BACKGROUND: An accelerated speed of fracture-healing in patients with traumatic brain injury (TBI) is often encountered in our clinical practice. However the mechanisms responsible for this phenomenon are remain unclear. After TBI, many cytokines or peptides has been reported change their expressions, suggest that the phenomenon of accelerated speed of fracture-healing may be associated with these cytokines or peptides. Calcitonin gene-related peptide (CGRP) is a neuropeptide which abundantly concentrated in bone metaphysis and periosteum,increases dramatically after brain injury. Also CGRP has an osteogenic stimulating effect. Therefore, we presume that CGRP may play a key role in accelerated fracture-healing. We have demonstrated that the hypothesis that the TBI causes the changes of CGRP level in serum that enhances fracture-healing, through establishment of a reproducible animal model of TBI in association with a standard closed fracture, and measured the speed of fracture-healing and detected the expression of CGRP in serum, brain tissues and muscles surrounding the fracture sites. To further verify the relation of CGRP and the phenomenon of accelerated speed of fracture-healing, we investigate the acceleration mechanisms of fracture healing, and observe the effect of exogenous CGRP on BMSCs and osteoclast.1. Detection of CGRP and CGRP receptor in accelerating fracture-healing in association with traumatic brain injuryOBJECTIVE: To detect the change of calcitonin gene-relate peptide CGRP and CGRP receptor in accelerating fracture-healing in association with traumatic brain injury. Methods: A standard closed femoral fracture was produced in Sprague-Dawley rats which were subjected to additional closed head trauma that produced diffuse axonal injury similar to that observed in patients with a TBI. Erebrospinal fluid, blood samples and bone tissues surrounding the fracture sites were collected from rats in every group atfive time points during the first week( 1h.24h.48h.72h.168h) after the procedure, The former was used to detect the concentration of CGRP by ELISA analysis, and the latter was used to detect CGRP receptor by qRT-PCR by analysis. RESULTS: Whether cerebrospinal fluid or blood, ELISA analysis indicated a high concentration of CGRP in TBI-fracture group (P<0.05), and qRT-PCR analysis showed a significant increase of CGRP receptor in bone tissues surrounding the fracture sites of TBI-fracture group at one week after fracture (P<0.05). CONCLUSIONS: These results support data from previous studies and further suggest that the mechanism for this enhancement of fracture-healing secondary to traumatic brain injury is closely related to the high level of CGRP which was released from brain tissue to the serum.2. The effects of calcitonin gene-relate peptide on rat bone marrow stromal cells and osteoclast:an in vitro studyOBJECTIVE: To investigate the effects of calcitonin gene-relate peptide on the proliferation of rat bone marrow stromal cells(BMSCs)and osteoclast. METHOD: BMSCs were isolated from rats by density gradient centrifugation and attachment method. Different dose of calcitonin gene-relate peptide (1×10-(11)1×10-6mol/L) were added to the culture media of the third passage BMSCs for the observation of proliferation (OD value at wavelength 450nm),differentiation (ALP detection and ALP staining) and mineralization(The cells were stained with alizarin red for the observation of calcium nodule) of the BMSCs. Effect of calcitonin gene related peptide on the formation of rat osteoclasts were detected by observing the number of TRAP 3. Study on mechanism of calcitonin gene-relate peptide on the differentiation of rat bone marrow stromal cellsOBJECTIVE: To explore the mechanism of calcitonin gene-relate peptide on the differentiation of rat bone marrow stromal cells. METHOD: BMSCs were isolated from rats by density gradient centrifugation and attachment method. Different dose of calcitonin gene-relate peptide (1×10-111×10-6mol/L) were added to the culture media of the third passage BMSCs,qRT-PCR was used to detect the expression of ALP, Collagen I, BMP-2, RunX2 and ON at different time points. RESULTS: qRT-PCR analysis showed a significant increase of BMP-2, RunX2, ALP, Collagen I and ON at different time points (P<0.001). CONCLUSIONS: The osteogenic differentiation of BMSCs were promoted by CGRP, BMP-2/Runx2 is the potential signal transduction pathway.. |
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