Original article
Adult cardiac
Novel Bioresorbable Vascular Graft With Sponge-Type Scaffold as a Small-Diameter Arterial Graft

Presented at the Fifty-second Annual Meeting of the Society of Thoracic Surgeons, Phoenix, AZ, Jan 23–27, 2016.
https://doi.org/10.1016/j.athoracsur.2016.01.110Get rights and content

Background

Current commercialized small-diameter arterial grafts have not shown clinical effectiveness due to their poor patency rates. The present study evaluated the feasibility of an arterial bioresorbable vascular graft, which has a porous sponge-type scaffold, as a small-diameter arterial conduit.

Methods

The grafts were constructed by a 50:50 poly (1-lactic-co-ε-caprolactone) copolymer (PLCL) scaffold reinforced by a poly (1-lactic acid) (PLA) nanofiber. The pore size of the PLCL scaffold was adjusted to a small size (12.8 ± 1.85 μm) or a large size (28.5 ± 5.25 μm). We compared the difference in cellular infiltration, followed by tissue remodeling, between the groups. The grafts were implanted in 8- to 10-week-old female mice (n = 15 in each group) as infrarenal aortic interposition conduits. Animals were monitored for 8 weeks and euthanized to evaluate neotissue formation.

Results

No aneurysmal change or graft rupture was observed in either group. Histologic assessment demonstrated favorable cell infiltration into scaffolds, neointimal formation with endothelialization, smooth muscle cell proliferation, and elastin deposition in both groups. No significant difference was observed between the groups. Immunohistochemical characterization with anti-F4/80 antibody demonstrated that macrophage infiltration into the grafts occurred in both groups. Staining for M1 and M2, which are the two major macrophage phenotypes, showed no significant difference between groups.

Conclusions

Our novel bioresorbable vascular grafts showed well-organized neointimal formation in the high-pressure arterial circulation environment. The large-pore scaffold did not improve cellular infiltration and neotissue formation compared with the small-pore scaffold.

Section snippets

Preparation for Bioresorbable Vascular Grafts

The grafts were constructed by pouring a solution of 50:50 PLCL into a glass tube, then freeze-drying under a vacuum as previously described [11]. The pore size was adjusted to obtain two different scaffold groups: small (12.8 ± 1.85 μm) and large (28.5 ± 5.25 μm; Fig 1). Next, these scaffolds were reinforced by electrospinning PLA nanofiber (40-μm thickness) to the outer side of the PLCL scaffold. Inner luminal diameters of each graft were approximately 600 μm.

Animal Model and Surgical Implantation

All animals received humane care

Animal Survival

Fifteen grafts for each group were implanted as infrarenal interposition aortic conduits. All mice in the small-pore group survived the 8-week implantation period with patent grafts. There were no complications, such as bleeding, acute thrombosis, aneurysmal change, or graft rupture (8 weeks), in the small-pore group. However, in the large-pore group, 2 mice were euthanized due to lower limb paralysis from acute thrombosis, and 1 mouse died of undetermined causes (the graft that was explanted

Comment

On the basis of current advances of our clinical trial using a bioresorbable vascular graft in a high-flow, low-pressure venous circulation, we demonstrated that a porous sponge-type scaffold has potential to be applied as a small-diameter vascular graft used in a high-flow and high-pressure arterial system. In this study, we applied an electrospinning technique to the outer layer of the graft to endure arterial pressures and prevent blood leakage from the scaffold [15]. This bilayered approach

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    Drs Sugiura and Tara contributed equally to this work.

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