BACKGROUND: Individual three-dimensional (3D) scaffolds can be constructed by 3D printing via Computer Aided Design based on the given anatomical measurements of related tissues. A rapid and accurate reconstruction of bone, cartilage, muscle and vessel also can be achieved by 3D printing; however, many problems still remain unsolved.OBJECTIVE: To summarize the principle and classification of 3D printing, the classification, characteristics and histocompatibility of scaffolds through reviewing the articles addressing 3D printing applied in bone tissue engineering,thereby providing theoretical foundation for the study on the construction of tissue-engineered bone.METHODS: PubMed and CNKI databases were retrieved for the literatures regarding the application of 3D printing technology in bone tissue engineering published from January 2001 to January 2017 using the keywords of three-dimensional printing, rapid prototyping manufacturing, bone tissue engineering in English and Chinese,respectively. Finally, 30 articles were reviewed and discussed in accordance with the inclusion and exclusion criteria.RESULTS AND CONCLUSION: The microstructures of normal tissues can be reconstructed and seed cells are printed on the 3D scaffolds synchronously by 3D printing technology. Moreover, the scaffold degradation and cell differentiation are synchronous, which contributes to tissue repair. Biological ceramics have been widely used in bone tissue engineering because of its good biocompatibility and mechanical properties. However, the urgent problems such as angiogenesis and cellular signal transduction still need to be addressed.

Objective To culture the rabbit bone marrow derived mesenchymal stem cells (BMSCs) ,and to observe their biologi-cal characteristics in vitro and the expression of BMP2 and EGFP after Ad-EGFP-BMP2 infected on them .Methods To isolate and cultivate BMSCs by density gradient centrifugation and adherent culture in vitro ;the cell cycle and the surface marks were detected by flow cytometer ;rabbit BMSCs were differentiated into the direction of osteogenetic cells by in vitro induction .After transfection , the expression of exogenous gene in the cells was detected by the immunocytochemical staining and Western blot .Results About 56 .84% of rabbit BMSCs cell cycle was in the G1 phase;the D44 expression was positive and the CD45 expression was negative ;af-ter induction by osteogenetic cells ,the Ⅰtype collagen immunohistochemical staining was positive and the alizarin red staining was positive .After transfection ,the strong expression of BMP2 and EGFP in cells was showed by Western blot and the immunocyto-chemical staining .Conclusion rabbit BMSCs are successfully isolated ,cultured and identified to have the ability of osteogenetic dif-ferentiation ;the structured Ad-BMP-2/EGFP can efficiently transfected rabit BMSCs and stably express the target gene of BMP 2 .

Objective To study the effects of short-term cryopreservation on the proliferation ,bio-characteristics and osteogenic capability of rabbit BMSCs and lay the foundation for the further study .Methods The 5th generation of rabbit BMSCs were cryo-preservated by liquid nitrogen for 30 days ,and then thawing the cells to culture it to the 10th generation in vitro ,put the non-cryo-preservated and the same generation BMSCs as the control group .The MTT ,cell cycle ,cell surface marker ,the content of ALP and the immunohistochemical staining for collagen typeⅠ and alizarin red staining for calcium after differentiation induced by osteogene-sis were used to evaluate the proliferation ,bio-characteristic and osteogenic differentiation capability of rabbit BMSCs .Results The growth incubation period of BMSCs after cryopreservated was extended ,but it gradually recover through serial passage .The prolif-eration index and the proportion of BMSCs in G1 phase were 42 .9% ± 3 .4% and 57 .0% ± 3 .4% respectively .The positive rate of cell surface marker of CD44 was 93 .62% ± 1 .05% without expression of CD45 .The contents of ALP(U/gprot) were 6 .73 ± 1 .92 and 15 .99 ± 4 .36 in BMSCs after 7th day and 14th day with osteogenic induction ,respectively .The collagen typeⅠ and alizarin red staining for calcium indicated positive at BMSCs after 14th day and 21th day with osteogenic induction ,respectively .These results showed no significant difference compared with the control group (P>0 .05) .Conclusion Short-term cryopreservation has no obvi-ous impacts on the proliferation ,bio-characteristic and osteogenic capability of BMSCs and it could be used for further study .

Objective To observe the biocompatibility of rabbit bone marrow mesenchymal stem cells (BMSCs)combined with allogeneic decalcified bone matrix(DBM)after transfecting adenoviral recombinant human bone morphogenetic protein-2(Ad-rhBMP-2).Methods The rabbit allogeneic DBM material was prepared according to the Ursit method.After transfecting Ad-BMP-2 on rabbit bone marrow mesenchymal stem cells,the immunohistochemical was used to detect the expression of BMP-2 in the transfected cells;after 48 h of transfection,the cells were planted on the allograft DBM,then the scanning electron microscopy was used to observe the cell growth and adhesion condition on material,and the proliferation condition of BMSCs was detected by MTT. Results After 48 h of adenoviral transfection,BMSCs could express BMP-2 successfully.The scanning electron microscopy showed that the cells after transfection adhered well and massively proliferated on DBM material.The MTT assay showed that the prolifer-ation condition of the cells after transfection planted on DBM was normal,which showed no statistically significant difference when compared with the control group (P >0.05).Conclusion The Ad-BMP-2 transfection on BMSCs is well biocompatible to allogene-ic DBM.

Objective: To explore the relationship of sleep quality and emotional regulation difficulties in middle school students, and to analyze its mediating role of daytime dysfunction, social rejection and selfcontrol ability, so as to provide a scientific reference for improving middle school students mental health. Methods: From October to November, 2023, the Pittsburgh Sleep Quality Index, Adolescent Social Rejection Questionnaire, Brief Selfcontrol Scale and Difficulties in Emotion Regulation Scaleshort Form (DERS-16) were used to assess 806 students recruited from four middle schools in Bengbu City by a convenient cluster random sampling method. And model-6 of PROCESS and 5 000 Bootstraps were used to make a chainmediating model analysis. Results: Daytime dysfunction was positively correlated with sleep quality(r=0.57), social rejection(r=0.19), selfcontrol(r=0.29, P＜0.01). Selfcontrol was positively correlated with emotional regulation difficulties(r=0.54, P<0.01).Poor sleep quality showed a significant positive association with on daytime dysfunction, and daytime dysfunction further affected social rejection, selfcontrol ability and emotional regulation difficulties (β=0.86, 0.60, 1.27, 1.56, P<0.05). Meanwhile, daytime dysfunction, social rejection and selfcontrol played a serial mediating role in the relationship between sleep quality and emotional regulation difficulties (Estimate=0.11,95%CI=0.04-0.20,P<0.05). Conclusion The study reveals the complex relationship between sleep quality and emotional regulation difficulties in middle school students and provides a new theoretical basis for adolescent sleep improvement and mental health interventions.