Division of Cardiac Surgery, Johns Hopkins Hospital, Baltimore, MD.
Center for Regenerative Medicine, Nationwide Children's Hospital, Columbus, OH.
J Tissue Eng Regen Med. 2020 Feb;14(2):203-214. doi: 10.1002/term.2977. Epub 2020 Jan 22.
Nanofiber vascular grafts have been shown to create neovessels made of autologous tissue, by in vivo scaffold biodegradation over time. However, many studies on graft materials and biodegradation have been conducted in vitro or in small animal models, instead of large animal models, which demonstrate different degradation profiles. In this study, we compared the degradation profiles of nanofiber vascular grafts in a rat model and a sheep model, while controlling for the type of graft material, the duration of implantation, fabrication method, type of circulation (arterial/venous), and type of surgery (interposition graft). We found that there was significantly less remaining scaffold (i.e., faster degradation) in nanofiber vascular grafts implanted in the sheep model compared with the rat model, in both the arterial and the venous circulations, at 6 months postimplantation. In addition, there was more extracellular matrix deposition, more elastin formation, more mature collagen, and no calcification in the sheep model compared with the rat model. In conclusion, studies comparing degradation of vascular grafts in large and small animal models remain limited. For clinical translation of nanofiber vascular grafts, it is important to understand these differences.
纳米纤维血管移植物已被证明可以通过体内支架的逐渐生物降解，在体内产生由自体组织构成的新生血管。然而，许多关于移植物材料和生物降解的研究都是在体外或小动物模型中进行的，而不是在大动物模型中进行的，因为大动物模型显示出不同的降解特征。在这项研究中，我们比较了纳米纤维血管移植物在大鼠模型和绵羊模型中的降解特征，同时控制了移植物材料的类型、植入时间、制造方法、循环类型（动脉/静脉）和手术类型（间置移植物）。我们发现，在植入后 6 个月，无论是在动脉循环还是静脉循环中，与大鼠模型相比，绵羊模型中的纳米纤维血管移植物的支架残留量明显较少（即降解速度更快）。此外，与大鼠模型相比，绵羊模型中存在更多的细胞外基质沉积、更多的弹性蛋白形成、更成熟的胶原，且没有发生钙化。总之，关于大动物和小动物模型中血管移植物降解的比较研究仍然有限。对于纳米纤维血管移植物的临床转化，了解这些差异非常重要。
