The effect of vacuum freeze-drying and radiation on allogeneic aorta grafts

Abstract

Vacuum freeze-dried aorta is a satisfactory material for blood vessel grafting. Previous studies have focused on immunity, however, vacuum freeze-drying is a complicated process of heat and mass transfer, and adopting a programmed cooling process may more completely preserve the mechanical properties of the blood vessels. Irradiation, as a method of removing pathogens, lowers the antigenic activity of the blood vessels. In our study, vacuum freeze-drying combined with radiation was used as a treatment for porcine aorta prior to grafting, aimed at deactivating endogenous retrovirus, shielding masses of endothelial cells and lowering the immunogenicity of the blood vessels. As for the mechanical properties, compared with normal aorta, the maximum axial tensile stress (ATS) decreased by 20%, the maximum circumferential tensile stress (CTS) increased by 30% and the maximum puncture stress (PT) decreased by 20%. Our results revealed that 2 months after of grafting, the host cells had migrated into the graft tissue and propagated to initiate endothelialization, the inflammatory reaction was abated and the PT had returned to normal levels.

Effects of Chemical and Radiation Sterilisation on the Biological and Biomechanical Properties of Decellularised Porcine Peripheral Nerves

“…In contrast to the PAA treated samples, the structure of the peripheral nerve extracellular matrix appeared to be well preserved after gamma irradiation or E beam treatment. This differs to some published studies on soft tissues, such as that of Cao et al (2013) which found that irradiation of freeze-dried aortas at 20 kGy caused widespread structural damage to the extracellular matrix, including the formation of small holes and a loss of luminal structure. Bonenfant et al (2013) found that decellularised murine lungs irradiated at 60 Gy suffered significant structural damage, particularly to the alveolar region.…”

“…Induces formation of cross-links if tissue is in a wet state, leading to increases in mechanical parameters such as stiffness or mechanical strength and preserves ECM architecture. If tissue is in a dry state, scission of the collagen chains predominates and causes degradation of the ECM and negatively affects mechanical properties (Cao et al, 2013) polymyxin B) for 30 min at 37 • C, then 200 mM EDTA (pH 7.2-7.4) for 24 h at 4 • C. Each segment was then washed in hypotonic buffer (10 mM Tris-HCL, 2.7 mM EDTA, 10 KIU/mL aprotinin; pH 8.0-8.2) for 24 h at 42 • C, followed by hypotonic buffer containing 0.1% (w/v) SDS for 24 h at 42…”

Structural design and mechanical performance of composite vascular grafts

“…The simplest method involves electrospinning a porous graft that is subsequently combined with the cells. In another strategy, porous grafts can be prepared by freeze drying [144][145][146], followed by cell diffusion. In addition, non-scaffold-based grafts can be prepared using the decellularized natural matrix technique.…”