Transforming growth factor-beta 1 expression in callus and the effect of callus bone graft on the post-operative function / 中国组织工程研究

ABSTRACT

BACKGROUND: In the healing process of fracture, if the callus tissue around the location of fracture is cleared, the end of fracture is difficult to be integrated completely, and more or less there would be some bone de fect. We deduce that these callus tissues are the necessary product during the process of bone reparation, which ought to be useful. Concerning this,we observed histological content and the volume of transforming growth factor-β1 (TGF-β1) with histological analysis and hybridization in situ of the frozen section of these calluses to investigate the effects of callus graft in the healing process of fracture.OBJECTIVE: To understand the salvaging value of bony callus organization around fracture in delayed operation by means of determining histological substances and contents of TGF-β1.DESIGN: Hybridization in situ of the callus tissue and randomized-grouping and controlled experiment.SETTING: Department of Orthopaedics, the Second Hospital of Xi'an Jiaotong University, and Department of Orthopaedics, Central Hospital of Taizhou City PARTICHANTS Totally 51 inpatients who received delayed fracture operations in the Department of Orthopaedics of the Second Hospital of Xi 'an Jiaotong University and Central Hospital of Taizhou City from July 1994 and October 2003 were recruited. In some cases of delayed fracture operation, callus was obtained with the consent of patients, Dig labeled kit was bought from Boehringer Mannheim Corp. CTT GCT GTA CTGTGT GTC CAA, TGF-β1 oligonucleotide probe sequence, was synthe sized by DNA synthesizer. Computer X-ray system was bought from Japan Fuji Corp. METHODS: 2,4,6,8 weeks after fracture, a small amounts of callus was obtained. Frozen section was made from undecalcified callus tissue, and noneisotope Dig labeled hybridization in situ, observe gene expression of TGF-β1 in callus. In the operation, after clearing the bone stump and fas tening the fracture, original bony callus was grafted to the bone defect and around the fracture. Simple callus graft, flank bone graft or both were adopted respectively on patients in delayed operation with follow-up obser vations were given for 1-4 years, with the average of 1 year and 9 months,at outpatient clinic for recheck.MAIN OUTCOME MEASURES: ① Histological substance and TGF-β1 content of bony callus at different phases of the fracture. ② Effect of different mode of bone graft on the time of fracture healing. RESULTS: Totally 51 cases were treated, and 7 cases were not followed up for death or moving to other areas. Data of the followed-up 44 patients were collected into the stage of result analysis. ① Gene expression of TGF-β1 in bone callus In the second week after fracture, there were a small amount of fibrous bone callus and comparatively much cartilage bone callus,and TGF-β1 was hypso-expressed in cartilage cells inside the cartilage islet; about four weeks later, TGF-β1 was notably expressed in os teoblasts; about eight weeks later, a host of calluses grew, mainly carti laginea, and the numbers of formed fibroblast, callus, osteoblasts and tra becular bone were increasing. TGF-β1 expression in all kinds of cells dis appeared after six weeks but had a tendency to rise again in bone matrix in the eighth week. ② There were no significant difference of healing time in different modes of bone graft .CONCLUSION: TGF-β1 plays an important role in balancing bone healing, and necessary connections exist between tissue change in bone callus and change in expression of TGF-β1. As callus is a product of recovery and reconstitution of organism, we regard callus graft salvage as a feasible method in reducing pain and damage to patients who need graft.