A novel alginate localization molding technique for cross-sectional area measurement of human tendon to access biomechanical properties.

Accurate determination of the biomedical properties of connective tissue such as tendons and ligaments is dependent on the accurate measurement of their cross-sectional area (CSA). To date, techniques for determining cross-sectional areas of ligaments and tendons have been less than ideal due to their complex geometries and their deformations under external load. A novel non-destructive technique has been developed for determining the cross-sectional area of tendon by locating the tendon rupture, in which aqueous rapid curing alginate dental molding materials, digital photography and computerized image analysis are utilized. This technique marks tendons and alginate molds at 1 cm interval and then tendons are taken out for tensile test. Real-time video is recorded to locate the position of tendon rupture. The corresponding alginate slice is found and then analysis through computer image processing software to obtain a more accurate CSA at tendon rupture, which can be used to calculate the stress and young's modulus of tendon. The accuracy of this technique has been investigated and comparisons have been made with the alginate un-localization molding technique and ellipse estimation technique. Results show this technique can provide accurate CSA values (within 2%) and great reproducibility (coefficient of variation = 0.8%). The technique is non-destructive, can obtain morphological information of soft tissue and can detect cavities.

3D bioprinted glioma microenvironment for glioma vascularization.

Glioblastoma is the most frequently diagnosed primary malignant brain tumor with unfavourable prognosis and high mortality. One of its key features is the extensive abnormal vascular network. Up to now, the mechanism of angiogenesis and the origin of tumor vascularization remain controversial. It is essential to establish an ideal preclinical tumor model to elucidate the mechanism of tumor vascularization, and the role of tumor cells in this process. In this study, both U118 cell and GSC23 cell exhibited good printability and cell proliferation. Compared with 3D-U118, 3D-GSC23 had a greater ability to form cell spheroids, to secrete vascular endothelial growth factor (VEGFA), and to form tubule-like structures in vitro. More importantly, 3D-glioma stem cells (GSC)23 cells had a greater power to transdifferentiate into functional endothelial cells, and blood vessels composed of tumor cells with an abnormal endothelial phenotype was observed in vivo. In summary, 3D bioprinted hydrogel scaffold provided a suitable tumor microenvironment (TME) for glioma cells and GSCs. This bioprinted model supported a novel TME for the research of glioma cells, especially GSCs in glioma vascularization and therapeutic targeting of tumor angiogenesis.

A 3D engineered scaffold for hematopoietic progenitor/stem cell co-culture in vitro.

Proliferation of HPSCs in vitro can promote its broad clinical therapeutic use. For in vitro co-culture, interaction between the stem cell and feeder cell as well as their spatial position are essential. To imitate the natural microenvironment, a 3D engineered scaffold for CD34+ cells co-culture was established via 3D bioprinting. Herein, the concentration of hydrogel and the ratio of two kinds of cells were optimized. Flow cytometry, real time PCR and RNA-seq technology were applied to analyze the effect of the engineered scaffold on expanded cells. After 10 days co-culture with the engineered scaffold, the expansion of CD34+CD38- cells can reach 33.57-folds and the expansion of CD34+CD184+ cells can reach 16.66-folds. Result of PCR and RNA-seq indicates that the CD34+ cells in 3D group exhibited a tendency of interaction with the engineered scaffold. Compared to 2D co-culture, this customizable 3D engineered scaffold can provide an original and integrated environment for HPSCs growth. Additionally, this scaffold can be modified for different cell co-culture or cell behavior study.