D4 - Biofabrication of Small-diameter Vascular Graft with Acellular Human Amniotic Membrane: A Proof-of-Concept Study in Pig

Introduction: : Expanded polytetrafluoroethylene (ePTFE) grafts are FDA-approved and effective for large and medium vessel surgeries but face challenges in small vessels (Inner Diameter, ID ≤ 6 mm) due to reduced blood flow and higher risks of thrombosis, stenosis, and infection.This study developed a vascular graft with an ID of 6 mm from decellularized human amniotic membrane (DAM graft) and compared its performance to ePTFE grafts in a porcine carotid ar-tery model.

Materials and

Methods: : DAM vascular grafts (6 mm ID) were prepared with elastin to enhance interlayer adhesion. Pigs underwent bilateral carotid artery replacement, where 2–3 cm segments were excised and replaced with either DAM or ePTFE grafts (5 cm) using end-to-end anastomosis with 8-0 nylon sutures. Standardized protocols for anesthesia, anticoagulation, and postoperative care were followed. One month post-implantation, grafts and control arteries were harvested, fixed in 4% formaldehyde, and analyzed via H&E, Sirius Red/Fast Green, and immunofluorescence staining (α-SMA, CD31, CD68) to evaluate tissue integration and immune response.

Results, Conclusions, and Discussions:: DAM grafts retained key extraceullular matrix (ECM) structures and mechanical properties post-decellularization, with customizable layers and stiffness to meet specific clinical needs. DAM grafts demonstrated successful carotid artery replacement, showing good surgical feasibility, patency, and post-operative recovery. In contrast to ePTFE grafts, which exhibited significant neointimal hyperplasia (NIH), poor endothelialization, and inflammation, DAM grafts displayed organized endothelial coverage, smooth muscle cell alignment, and reduced inflammation, min-imizing NIH, thrombosis, and graft failure. These findings position DAM grafts as a promising al-ternative to synthetic grafts, especially for small-diameter applications. Future research should focus on improving endothelialization, exploring molecular mechanisms, and assessing long-term outcomes to further optimize DAM grafts for clinical use.

Acknowledgements and/or References (Optional):: Research reported in this publication was supported by the Advancing a Healthier Wiscon-sin (AHW) Endowment.