BACKGROUND AND OBJECTIVES: Mesenchymal stem cells (MSCs) become hypertrophic in long term despite chondrogenic differentiation following the pathway of growth plate chondrocytes. This terminal differentiation leads to phenotypically unstable cartilage and was mirrored in vitro by addition of hypertrophy inducing medium. We investigated how intrinsic TGF-β signaling is altered in pro-hypertrophic conditions. METHODS AND RESULTS: Human bone marrow derived MSC were chondrogenically differentiated in 3D culture. At day 14 medium conditions were changed to 1. pro-hypertrophic by addition of T3 and withdrawal of TGF-β and dexamethasone 2. pro-hypertrophic by addition of BMP 4 and withdrawal of TGF-β and dexamethasone and 3. kept in prochondrogenic medium conditions. All groups were treated with and without TGFβ-type-1-receptor inhibitor SB431542 from day 14 on. Aggregates were harvested for histo- and immunohistological analysis at d14 and d28, for gene expression analysis (rt-PCR) on d1, d3, d7, d14, d17, d21 and d28 and for Western blot analysis on d21 and d28. Induction of hypertrophy was achieved in the pro-hypertrophic groups while expression of TGFβ-type-1- and 2-receptor and Sox 9 were significantly downregulated compared to pro-chondrogenic conditions. Western blotting showed reduced phosphorylation of Smad 2 and 3 in hypertrophic samples, reduced TGF-β-1 receptor proteins and reduced SOX 9. Addition of SB431542 did not initiate hypertrophy under pro-chondrogenic conditions, but was capable of enhancing hypertrophy when applied simultaneously with BMP-4. CONCLUSIONS: Our results suggest that the enhancement of hypertrophy in this model is a result of both activation of pro-hypertrophic BMP signaling and reduction of anti-hypertrophic TGFβ signaling.
Blotting, Western ; Bone Marrow ; Cartilage ; Chondrocytes ; Chondrogenesis ; Dexamethasone ; Down-Regulation ; Gene Expression ; Growth Plate ; Humans ; Hypertrophy ; In Vitro Techniques ; Mesenchymal Stromal Cells ; Phosphorylation

Trauma registration is an important tool to record the process and timeline in the treatment of trauma patients. The operation of trauma database is of great significance for reducing the mortality of patients, promoting the construction of trauma treatment system, and providing reference for policy-making. Trauma registration system has been established in the United States, United Kingdom, Germany and other developed countries for many years. However, the domestic system is still at an initial stage, and there are problems like data deficiencies, data incoherence, no item of complications, no treatment data after discharge and limits of human and financial resources. Therefore, there is room for improvements in terms of personnel fixation, financial support and continuous data monitoring should be further improved. In this study, the authors summarize the traum registration system from aspects of basic situation both at home and abroad, data analysis, clinical value, operation mechanism and challenges so as to provide important data for clinical researches.