ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of inhibition and activation of MAPK-ERK1/2 pathway on the expression of osteogenic genes and proliferation of rat osteoblasts in vitro.</p><p><b>METHODS</b>Primarily cultured rat osteoblasts, identified by cell morphology studies and ALP staining, were exposed to 1% or 5% rat serum for 24 h or to the specific MAPK-ERK1/2 inhibitor PD0325901. The downstream molecules of MAPK-ERK1/2 pathway including p-ERK1/2 and ERK1/2, osteogenic genes such as Runx2 and Type I collagen, and proliferating cell nuclear antigen (PCNA) were detected by Western Blotting, and alkaline phosphatase activities were analyzed quantitatively.</p><p><b>RESULTS</b>Compared with 1% rat serum-treated cells, exposure of the cells to a higher concentration (5%) of rat serum caused a significantly increased phosphorylation level of p-ERK1/2 (P<0.05) and obviously enhanced expressions of the osteogenic genes (Runx2, type I collagen and ALP) and PCNA (P<0.05). Inhibition of the MAPK-ERK1/2 pathway with PD0325901 resulted in suppressed expressions of the osteogenic genes and PCNA.</p><p><b>CONCLUSION</b>The activation of MAPK-ERK1/2 pathway promotes the expression of osteogenic genes such as Runx2, type I collagen and ALP and enhances the proliferative activity of the osteoblasts, while inhibition of this pathway suppresses the expressions of these genes and the cell proliferation, suggesting that this pathway may potentially serve as a therapeutic target for osteoporosis.</p>
Subject(s)
Animals , Female , Male , Rats , Alkaline Phosphatase , Metabolism , Antineoplastic Agents , Pharmacology , Benzamides , Pharmacology , Cell Proliferation , Cells, Cultured , Collagen Type I , Metabolism , Core Binding Factor Alpha 1 Subunit , Metabolism , Diphenylamine , Pharmacology , Gene Expression Regulation , MAP Kinase Signaling System , Mitogen-Activated Protein Kinase 1 , Metabolism , Mitogen-Activated Protein Kinase 3 , Metabolism , Osteoblasts , Cell Biology , Metabolism , Phosphorylation , Proliferating Cell Nuclear Antigen , Metabolism , Rats, Sprague-DawleyABSTRACT
[Objective]To seek for a method to rebuild radial head for comminuted radial head fractures,and recommend a new technique of bipolar radial head replacement.[Method]Five patients with fresh comminuted radial head fractures were treated by Tornier cement stem and bipolar radial prothesis.Among them,three were females and two were males,with the average age of 37.4Y(29-48Y).Four cases were to Mason type Ⅲ and one Mason type Ⅳ.All the patients underwent operation within 3-11 days with an average of 6 days after injury.Rehabilitation began in Mason type Ⅲ radial head fracture patients 48 h postoperatively.Both medial and lateral ligaments were repaired in one case of Mason type Ⅳ fracture.Plastic brace were used for 3 weeks during functional rehabilitation.The postoperative elbow joint was evaluated clinically by Broberg and Morrey score.[Result]All the patients healed by first intention were followed up for 7 to 50 months,with an average of 30 months.According to elbow functional evaluation criteria by Broberg and Morrey scores,there were excellent results in three and good in two respectively with an average of 92.2 points.[Conclusion]Cement stem and bipolar radial head prothesis replacement is a good technique for treating comminuted radial head fractures because it meets the designing principle of modern orthopaedics.