Transforming growth factor beta as a regulator of the regional expression of the immune cytokines in xenogeneic bone transplantation / 中国组织工程研究

ABSTRACT

BACKGROUND: For xenogeneic bone transplantation, immune rejection is the major problem that affects the prognosis. However, the understanding about the expression and regulation of the immune factors in heterogenic bone transplantation is limited. Interleukin-1 (IL-1), interleukin-6 (IL-6)and tumor necrosis factor alpha (TNF-α) are important immune factors, and are closely related with post-transplantation rejection.OBJECTIVE: To observe the regional expressions of mRNA and protein of IL-1α, IL-6 and TNF-α in xenogeneic bone transplantation, and to in vestigate the effect of transforming growth factor (TGF)-β on these immune factors.DESIGN: A randomized controlled experiment. SETTING: The Orthopaedic Institute of Xijing Hospital of the Fourth Military Medical University of Chinese PLA MATERIALS Totally 72 male Balb/c mice, with a body mass of 20 to 25 g, were randomly divided into 3 groups combined bovine cancellous bone (bCB) granule group (Group A), simple bCB granule group (Group B) and blank control group (Group C) with 24 mice in each group.INTERVENTIONS: This experiment was conducted at the Institute of Orthopaedics, Xijing Hospital, Fourth Military Medical Univessity of Chinese PLA from June 2003 to June 2004. In Group A, one bCB combined TGF-β was implanted into the muscles of left thigh of each mouse. In Group B, one bCB alone was implanted, and in Group C, no bCB was implanted. The number of proliferation of cells in bone implantation area or adjacent tissues of the operated area was observed at postoperative 4, 7, 14 and 21 days; and the regional expressions of several immune factors in im plants were detected with in situ hybridization and immunocytochemistry methods.MAIN OUTCOME MEASURES: Histological observation and detection of regional cellular density of the implants of the mice in each group; the regional expressions of mRNA and protein of IL-1α,IL-6 and TNF-α in the implants RESULTS: ①) Histological observation and detection of regional cellular density of the implants of the mice in each group on day 7, the cellular density of the proliferated tissues was significantly higher in the Group A than in the Group B [(470.63±132.89), (311.46±93.69)/field,P ＜ 0.01];But on days 14 and 21, there was no significant difference. ②The regional expressions of mRNA and protein of IL-lα, IL-6 and TNF-α of the im plants of the mice in each group. On days 7 and 14 after xenografts were implanted, the regional expressions of IL-1α, IL-6 was respectively lower the xenografts combined with TGF-βthan in the simple xenogeneic bone (day 7 IL-1α 42.55±9.65 vs 67.95±17.82,IL-6 48.26±11.17 vs 77.21±15,16;day 14 IL-1α mRNA 84.77 ±7.42 vs 112.94±7.02,78.1 ±17.22 vs 121.18±15.44,P ＜ 0.01) ,but for the TNF-α, there was no significant difference (P ＞ 0.05).CONCLUSION: In the region of bone xenograft, a variety of cells express mRNAs and proteins of IL-1α, IL-6 and TNF-α, and their expressions are regulated by TGF-β. It may imply a kind of regulation of the immunity of bone xenograft by TGF-β.