Three-dimensional bioprinting is not only about cell-laden structures / 中华创伤杂志(英文版)

In this review, we focused on a few obstacles that hinder three-dimensional (3D) bioprinting process in tissue engineering. One of the obstacles is the bioinks used to deliver cells. Hydrogels are the most widely used bioink materials; however, they aremechanically weak in nature and cannot meet the requirements for supporting structures, especially when the tissues, such as cartilage, require extracellular matrix to be mechanically strong. Secondly and more importantly, tissue regeneration is not only about building all the components in a way that mimics the structures of living tissues, but also about how to make the constructs function normally in the long term. One of the key issues is sufficient nutrient and oxygen supply to the engineered living constructs. The other is to coordinate the interplays between cells, bioactive agents and extracellular matrix in a natural way. This article reviews the approaches to improve the mechanical strength of hydrogels and their suitability for 3D bioprinting; moreover, the key issues of multiple cell lines coprinting with multiple growth factors, vascularization within engineered living constructs etc. were also reviewed.

Physical Examination and Computed Tomography in Children with Toe in Gait

OBJECTIVE: To determine the correlation between the physical examination and the computed tomography of femoral anteversion and tibial internal torsion. METHOD: The angle of internal and external rotation of hip for femoral anteversion and thigh-foot angle for tibial internal torsion were measured by a rehabilitation physician for 116 young children with toe in gait. Within a week after the physical examination, the angle of femoral anteversion and tibial internal torsion were measured by computed tomography for comparison. RESULTS: Two-hundred thirty-two lower limbs of 116 children (64 girls and 52 boys) included in this study whose mean age was 6.4+/-2.7 years for girls and 6.8+/-2.8 years for boys. The Pearson correlation coefficient between the angle of internal rotation of the hip and the femoral anteversion measured by computed tomography showed 0.62 in right side and 0.55 in left side, an indication of significant correlation (p<0.01). The Pearson correlation coefficient between the thigh-foot angle and the tibial internal torsion measured by computed tomography showed 0.50 in right side, 0.42 in left side, an indication of significant correlation (p<0.01). CONCLUSION: Children with toe-in gauts showed a significant correlation between finding of physical exam (i.e. TFA and femoral internal torsion angle) and those of CT omages (i.e. tibial torsion angle and femoral torsion angle).