Harnessing oriented arrangement of collagen fibers by 3D printing for enhancing mechanical and osteogenic properties of mineralized collagen scaffolds.

As the structural basis of connective and load-bearing tissues, collagen fibers with orientation play an important role in the mechanical properties and physiological and biochemical functions of the tissues, but viable methods for preparing scaffolds with highly oriented collagenous structure still need to be further studied. In this study, pure collagen was used as printing ink to 3D printing. Harnessing oriented collagen fiber structure by 3D printing for promoting mechanical and osteogenic properties of scaffolds. The scaffolds with different printed angles and thicknesses were prepared to fit the bone defect site and realize personalized customization. The orientation assembly of collagen fibers was promoted by shear force action of 3D printing, the regular arrangement of collagen fibers and stabilization of fiber structure were promoted by pH adjustment and glutaraldehyde cross-linking, and the collagen fibers were mineralized by cyclic mineralization method. The microscopic morphology of fiber arrangement in the scaffolds were investigated by scanning electron microscopy. Results demonstrated that collagen fibers were changed from non-oriented to oriented after 3D printing. And the tensile modulus of the scaffolds with oriented collagen fibers was nine times higher than that of the scaffolds with non-oriented fibers. Moreover, the effects of oriented collagen fibers on the proliferation, differentiation and mineralization of MC3T3-E1 cells were studied by CCK-8 assay, live/dead cell staining, alkaline phosphatase activity test, and Alizarin red staining. The results indicated that cell proliferation, differentiation and mineralization were significantly promoted by oriented collagen fibers, and the cells proliferated directionally in the direction of the fibers. Taken together, mineralized collagen fiber scaffolds with oriented collagen fibers have great potential in bone tissue engineering applications.

[Clinical observation of acupotomy combined with warm needling for cervical spondylotic radiculopathy of qi and blood stagnation syndrome].

OBJECTIVE: To observe the clinical effect of acupotomy combined with warm needling on cervical spondylotic radiculopathy (CSR) of qi and blood stagnation syndrome. METHODS: A total of 90 CSR patients were randomly divided into an acupotomy group, a warm needling group and a combined treatment group, with 30 cases in each group. The patients in the acupotomy group were treated with acupotomy, once every 7 days, consecutively for 3 times. The patients in the warm needling group received warm needling, once daily, at the interval of 2 days after consecutive treatments for 5 days, 7 days as one session of treatment and 3 consecutive sessions were required. The patients in the combined treatment group were treated with acupotomy and warm needling, and the methods and the treatment session were same as the the previous two groups. Before and after the treatment, the pain rating index (PRI) of McGill pain questionnaire (MPQ) and the 20-point scale of CSR developed by Yasuhisa Tanaka (CSR20) were adopted in the assessment. The changes of clinical symptoms and functions of patients were observed and the clinical efficacy was assessed in each group. RESULTS: After the treatment, the PRI score was decreased (P<0.05) and the CSR20 score was increased (P<0.05) in the 3 treatment groups when compared with those before the treatment. After the treatment, compared with the acupotomy group and the warm needling group, the PRI score was decreased (P<0.05) and the CSR20 score was increased (P<0.05) in the combined treatment group. The total effective rate was 83.3% (25/30) in the acupotomy group, 76.7% (23/30) in the warm needling group and 93.3% (28/30) in the combined treatment group. The total effective rate in the combined treatment group was higher than those in the acupotomy group and the warm needling group (P<0.05). CONCLUSION: The combined treatment with acupotomy and warm needling may obviously improve the clinical symptoms and physical signs, e.g. pain and numbness in the patients with CSR of qi and blood stagnation syndrome. Its efficacy is remarkably higher than that of the simple application of acupotomy or warm needling.