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Bioprinting of living aortic valve
Published in Ali Khademhosseini, Gulden Camci-Unal, 3D Bioprinting in Regenerative Engineering, 2018
D.Y. Cheung, S. Wu, B. Duan, J.T. Butcher
Fibrin perhaps has been the more popular material for TEHV. Fibrinogen can be isolated from a patient’s own blood, so once combined with thrombin, an autologous fibrin scaffold can be produced, which has immediate clinical applications (Ye et al. 2000). In addition to the possibility of making autologous scaffolds, fibrin has been a popular choice due to its biocompability within the host and the ability for cells to infiltrate the scaffold (Ahmed et al. 2008; Flanagan et al. 2009). Fibrin can also promote collagen production and enhance GAG retention within the developing ECM (Alfonso et al. 2013). Researchers have seeded vascular cells onto molded fibrin scaffolds and implanted the TEHV into sheep (Flanagan et al. 2007, 2009). The explants showed qualitatively similar matrix organization when compared to native valves. However, fibrin and other biological protein-based TEHV are susceptible to cell-mediated contractions, which could be due to the stress differential between the stress generated by the leaflets (i.e. cells) and the stress on the leaflets (i.e. diastolic pressure), leading to leaflet retraction or weakened scaffold (van Loosdregt et al. 2014). To overcome this limitation, some groups have combined naturally derived polymers with other materials, synthetic or naturally derived. One group has developed a scaffold that contained a mixture of fibrin-coated collagen–glycosaminoglycans sheets that yielded stronger mechanical properties than fibrin scaffolds and showed no cell-mediated reduction in scaffold size after culturing in vitro (Brougham et al. 2015). Others have fabricated elastin sheets on top of hydrogels containing cross-linked hyaluronan, but these have yet to be used in vivo (Ramamurthi and Vesely 2005).
Improved mechanical properties by modifying fibrin scaffold with PCL and its biocompatibility evaluation
Published in Journal of Biomaterials Science, Polymer Edition, 2020
Lei Yang, Xiafei Li, Dongmei Wang, Songfeng Mu, Wenhao Lv, Yongwei Hao, Xiaosheng Lu, Guojiang Zhang, Wenbin Nan, Hongli Chen, Liqin Xie, Yongjun Zhang, Yuzhen Dong, Qiqing Zhang, Liang Zhao
The results showed that PCL/fibrin scaffolds had larger fiber diameter and smaller aperture than fibrin scaffold. The electrospun PCL/fibrin scaffolds have balanced mechanical properties, hemocompatibility, degradability and cell compatibility, and the mechanical properties of the scaffolds can be accelerated due to the addition of the PCL. However, excessive amount of PCL would impair the cell compatibility properties. Particularly, PCL/fibrin (20:80) scaffold exhibited balanced mechanical properties and degradability, as well as good cell compatibility properties; therefore, it was a promising tissue engineering material for vascular graft. Histological findings of the implanted PCL/fibrin scaffolds illustrated good tissue compatibility. After four weeks following subcutaneous in vivo implantation into SD rats, PCL/fibrin vascular scaffold degraded faster than PCL. In all, PCL/fibrin scaffold prepared by electrostatic spinning technology had excellent biomechanical properties, biocompatibility and degradability, making it ideal scaffolds for small diameter tissue engineering blood vessels.