In vitro evaluation of marrow clot enrichment on microstructure decoration, cell delivery and proliferation of porous titanium scaffolds by selective laser melting three-dimensional printing.

Titanium alloy is a clinically approved material for bone substitution. Although three-dimensional printing (3DP) fabrication technique can build up porous Ti scaffolds with the designed shape and microstructure, the biomechanical performance of 3DP Ti scaffolds still need to be improved to increase the reliability of osseointegration capacity. To address this issue, rabbit bone marrow clot (MC) is used to modify 3DP Ti scaffolds by stem cell delivery and microenvironment decoration inside the pores of these scaffolds. Moreover, 3DP Ti scaffolds were built up using selective laser melting, and 3DP MC-Ti scaffolds were constructed through the enrichment of MC with Ti scaffolds in vitro. Results demonstrated that the obtained 3DP Ti scaffolds in current study has an average modulus of elasticity (ME) at 1294.48 MPa with average yield strength of 33.154 MPa. For MC-Ti scaffolds, MC enrichment obstructs the pores of 3DP scaffolds due to the large amount of fibrin and erythrocytes and leads to a decrease in ratio of live cells at 1-week culture. Cell proliferation and osteogenic differentiation performance of MC-Ti scaffolds were promoted with porous recanalization in the later 3 weeks. After 2 weeks in vitro culture, fivefold of cell number in MC-Ti scaffolds were observed than bone marrow-derived mesenchymal stem cell-seeded Ti scaffolds. Compared to Ti scaffolds, fourfold of deoxyribonucleic acid content, type I collagen-α1, osteocalcin, and alkaline phosphatase expression in MC-Ti scaffolds were observed after 4 weeks in vitro culture. Results suggested that the combination with MC is a highly efficient method that improves the biological performance of Ti scaffolds. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2245-2253, 2018.

Application of 3D printing rapid prototyping-assisted percutaneous fixation in the treatment of intertrochanteric fracture.

The aim of the present study was to investigate the application of 3D printing (3DP) rapid prototyping (RP) technique-assisted percutaneous fixation in the treatment of femoral intertrochanteric fracture (ITF) using proximal femoral nail anti-rotation (PFNA). A total of 39 patients with unstable ITF were included in the current study. Patients were divided into two groups: 19 patients were examined using computed tomography scanning and underwent PFNA with SDP-RP whereas the other 20 patients underwent conventional PFNA treatment. Anatomical data were converted from the Digital Imaging and Communications in Medicine format to the stereolithography format using M3D software. The 3DP-RP model was established using the fused deposition modeling technique and the length and diameter of the main screw blade was measured during the simulation. The postoperative femoral neck-shaft angle (NSA), surgery duration, intraoperative and postoperative blood loss, and the duration of hospital stay were recorded and compared with the corresponding values in conventional surgery. No significant differences were observed in mean PFNA size between the implants used and the preoperative planning estimates. It was demonstrated that the 3DP-RP assisted procedure resulted in more effective reduction of the NSA. Furthermore, patients undergoing 3DP-RP experienced a significant reduction in duration of surgery (P<0.01), as well as reductions in intraoperative (P=0.02) and postoperative (P=0.03) blood loss, compared with conventional surgery. At 6 months post-surgery, no cases of hip varus/vague deformities or implant failure were observed in patients that underwent either the 3DP-RP-assisted or conventional procedure. The results of the present study suggest that the 3DP-RP technique is able to create an accurate model of the ITF, which facilitates surgical planning and fracture reduction, thus improving the efficiency of PFNA surgery for ITFs.

[MRNA expression of complement C3 and C4 in rat nasal mucosa with allergic rhinitis].

OBJECTIVE: To investigate the level of mRNA expression of complement C3 and C4 in rat nasal mucosa and to reveal the relationship with the pathogenesis of allergic rhinitis (AR) . METHODS: Twenty healthy SD rats were randomly divided into AR group and control group, 10 rats for each group. Ten rats was sensitized and intranasally challenged by ovalbumin and Al (OH)3 (as supplement) as allergic rhinitis models, and the control group was treated by saline. RT-PCR was performed to investigate the level of mRNA expression of complement C3 and C4 in nasal mucosa of both groups. RESULTS: C3 and C4 mRNA were detected in both groups. The relative intensity of gene expression was measured. The relative intensity of C3 mRNA expression was 6183+/-1376 in AR group, 4444+/-989 in control group, C4 mRNA was 4398 +/-948 in AR group, and 2771+/-407 in control group. Expression of C3 and C4 in AR group was higher than that of the controls ( P < 0. 05) . CONCLUSION: The high level of C3 and C4 mRNA expression in nasal mucosa of rats with allergic rhinitis suggests that C3 and C4 are involved in the immunopathology of allergic rhinitis. The result implies that complement system involved in the rat's allergic rhinitis is possibly activated through the classical pathway.