BACKGROUND: Demineralized bone matrix (DBM) has natural mesh pores, good plasticity and biocompatibility. However, the decalcification time in preparation of DBM remains controversial.OBJECTIVE: To compare effects of varying degrees of decalcification with DBM on the proliferation of bone marrow stromal stem cells (BMSCs) so as to provide the best DBM scaffold for cartilage tissue engineeringMETHODS: Rabbit iliac bones were prepared into strips, defatted, followed by 6,12 and 24 hours of decalcification and 2 days of soaking in alcohol to prepare DBM. DBMs were placed in 24-well plates. The third passage of BMSCs at a density of 5×10~9/L were incubated on 24-well plate with DBMs. The DBM porosity and pore size were observed by scanning electron microscopy;BMSCs proliferation on the DBM was determined by MTT, and cell attachment on DBM was observed by scanning electron microscopy.RESULTS AND CONCLUSION: DBM displayed natural high-density porous grid structure, in the presence of bone trabecula,trabecular space and bone luminal system. The porosity and pore size of DBM decalcified for 6,12 and 24 hours were similar (P > 0.05). Compared with decalcified for 12 and 24 hours, BMSCs attached to DBM decalcified for 6 hours more closely and the DBM showed better compatibility. SEM observation showed the BMSCs on DBMs decalcified for 6 hours proliferated stably after 8 days and applicable for transplantation. Moreover, the number of cells were significantly more than DBMs decalcified for 12 and24 hours (P< 0.01).

BACKGROUND: Demineralized bone matrix (DBM) having a great biocompatibility is a common material to repair bone defect in clinic Bone marrow stromal cells (BMSCs) which can differentiate into bone and cartilage cells are ideal for repairing cartilage defect. OBJECTIVE: To observe the effects of allograft DBM combined with autograft BMSCs on repairing the articular cartilage of rabbits. METHODS: Bone and cartilage defect was induced in 27 rabbits and the models were randomly divided into combined group (DBM combined with 8-day-curtured autograft BMSCs), DBM group (DBM implantation alone), and control group. The reparative tissue samples were evaluated grossly, histologically, and immunohistochemically. The repairing effect was evaluated by Wakitani's score system.RESULTS AND CONCLUSION: The repaired tissues were hyaline cartilage-shaped, smooth and glossy, and well combined with peripheral cartilage and subchondral tissues at 12 weeks after implantation in the combined group; some tissues were cartilage-likely repaired in the DBM group; a few of tissues were fiber-like repaired in the control group. Immunohistochemical staining showed that type Ⅱ collagen was positive in both combined and DBM groups. Repaired cells which could express type Ⅱ collagen were cartilage cells. However, the expression of type Ⅱ collagen was negative in the control group. At 4,8, and 12 weeks after implantation, the scores in the combined group were significantly higher than in the DBM and control groups (P < 0.01), suggesting that DBM/BMSCs complex could be an efficient graft to repair the articular cartilage defects.

Objective To explore the repair result of full-thickness cartilage defects in diannan small-ear pig by bone mesenchymal stem cells (BMSCs) transferred with both transforming growth factor-β3(TGF-β3) and bone morphogenetic protein-2(BMP-2) gene mediated by adenovirus vector and combined with deminerized bone matrix (DBM). Methods 32 full-thickness defects from 16 knees of 8 pigs were randomly divided into 4 groups in the experiments. In group A, the animals′ lateral femoral condyle of right knee joint was repaired with DBM and BMSC infected with both Ad-TGF-β3 and Ad-BMP-2. In group B, the medial femoral condyle of right knee joint was repaired with DBM and BMSC without infection. In group C, the lateral femoral condyle of left knee joint was repaired with DBM. And the group D is control group. Morphology and histology were observed 2, 4, 8 and 12 weeks after operation. Results 12 weeks after operation, the whole defects were repaired in group A, HE staining showed typical cartilaginous structure in the repaired area. In group D, defects were not repaired but filled with fibrous tissue. The O′driscoll scores were 15.65 ± 0.11 (group A), 11.33 ± 0.22 (group B), 6.13 ± 0.15 (group C) and 5.08 ± 0.15 (group D). There was significant difference among the groups (P < 0.05). Conclusions The new type of tissue engineering scaffold that DBM combined with BMSCs transfected with both Ad-BMP-2 and Ad-TGF-β3 could induce cartilage regeneration and repair the defects.

Objective:To compare the dosimetric difference between 3D-printed multi-channel applicator and conventional vaginal single-channel applicator for brachytherapy, aiming to provide guidance for patients receiving brachytherapy after cervical cancer surgery.Methods:From January 2019 to November 2020, 25 cervical cancer patients complicated with VAIN Ⅲ receiving 192Ir high-dose-rate brachytherapy after cervical cancer surgery were selected. Each patient was located by CT scanning with 3D-printed multi-channel applicator and conventional vaginal single-channel applicator, and corresponding plan and evaluation were carried out. The dose volume histogram (DVH) was obtained by inverse dose optimization algorithm. The dosimetric differences of high-risk clinical target volume (HRCTV), bladder and rectum during brachytherapy were compared with those of source applicators. The optimal treatment plan was selected. Results:D 90%, D 100%, V 100% and V 150% of the plans designed by 3D-printed individual multi-channel applicator had no significant differences compared with those designed by conventional single-channel applicator (all P>0.05). The bladder and rectal D 2cm 3 designed by 3D-printed multi-channel applicator were significantly lower than those using conventional single-channel applicator, and the differences were statistically significant (both P<0.05). Conclusion:The multi-channel individual applicator target made by 3D-printing technology has good conformal property, properly protects the bladder and rectum and possesses treatment advantages over conventional single-channel applicator.