Using Multilayered Hydrogel Bioink in Three-Dimensional Bioprinting for Homogeneous Cell Distribution.

During the extrusion-based three-dimensional bioprinting process, liquid-like bioinks with low viscosity can protect cells from membrane damage induced by shear stress and improve the survival of the encapsulated cells. However, rapid gravity-driven cell sedimentation in the reservoir could lead to an inhomogeneous cell distribution in bioprinted structures and therefore hinder the application of liquid-like bioinks. Here, we developed a novel multilayered modified strategy for liquid-like bioinks (e.g., gelatin methacryloyl with low viscosity) to prevent the sedimentation of encapsulated cells. Multiple liquid interfaces were manipulated in the multilayered bioink to provide interfacial retention. Consequently, the cell sedimentation action going across adjacent layers in the multilayered system was retarded in the bioink reservoir. It was found that the interfacial retention was much higher than the sedimental pull of cells, demonstrating a critical role of the interfacial retention in preventing cell sedimentation and promoting a more homogeneous dispersion of cells in the multilayered bioink.

Bioprinting a 3D vascular construct for engineering a vessel-on-a-chip.

The organ-on-a-chip model mimics the structural and functional features of human tissues or organs and has great importance in translational research. For vessel-on-a-chip model, conventional fabrication techniques are unable to efficiently imitate the intimal-medial unit of the vessel wall. Bioprinting technology, which can precisely control the organization of cells, biomolecules, and the extracellular matrix, has the potential to fabricate three-dimensional (3D) tissue constructs with spatial heterogeneity. In this study, we applied the gelatin-methacryloyl-based bioprinting technology to print 3D construct containing endothelial cells (ECs) and smooth muscle cells (SMCs) on a microfluidic chip. Compared with traditional culture system, EC-SMC coculturing chip model upregulated αSMA and SM22 protein expression of the SMC to a greater degree and maintains the contractile phenotype of the SMC, which mimics the natural vascular microenvironment. This strategy enabled us to establish an in vitro vascular model for studies of the physiologic and pathologic process in vascular wall.

Improving operation notes to meet British Orthopaedic Association guidelines.

INTRODUCTION: Operation notes are an important part of medical records for clinical, academic and medicolegal reasons. This study audited the quality of operative note keeping for total knee replacements against the standards set by the British Orthopaedic Association (BOA). PATIENTS AND METHODS: A prospective review of all patients undergoing total knee replacement at a district general hospital over 8 months. Data recorded were compared with those required by the BOA good-practice guidelines. Change in practice was implemented and the audit cycle completed. Data were statistically analysed. RESULTS: A total of 129 operation notes were reviewed. There was a significant improvement in the mean number of data points recorded from 9.6 to 13.1. The least well recorded data were diagnosis, description of findings, alignment and postoperative flexion range. All had a significant improvement except description of findings. The operating surgeon writing the note improved from 56% to 67%. Detailed postoperative instructions also improved in quality. CONCLUSIONS: Surgeon education and the use of a checklist produce better quality total knee replacement operation notes in line with BOA guidelines. Further improvements may be made by making the data points part of the operation note itself.