146. A Novel 3D Printed Sacrificial Material for the Development of Perfused Intricate Blood Vessel Structures

“

TL;DR

Researchers developed a novel method using 3D-printed polyvinyl alcohol (PVA) as a sacrificial material to create perfused blood vessel structures with intricate shapes and diameters as small as 750 microns. The PVA loops could be sterilized without degradation, showed no significant cytotoxicity, and supported the formation of aligned endothelial and smooth muscle cell layers under flow. This technique may enable the engineering of larger, vascularized tissue flaps for reconstructive surgery.

Full summary

3,056 CHARS

**Background:** Reconstructive surgeons often rely on autologous donor tissue for defect restoration, but this approach has drawbacks including donor site morbidity, limited donor sites, and risks from prolonged operative time. Tissue engineering offers a potential alternative, but the maximum nutrient diffusion distance for cell survival is 100–200 μm, which restricts the size of fabricated flaps. While various materials can be shaped and removed to create hollow channels for blood vessels, they cannot be scaled below a few millimeters, and small needles (~200 μm) are limited to straight vessels. This study proposes using polyvinyl alcohol (PVA) filament for 3D printing intricate designs that can be dissolved to generate hollow chambers for seeding cells, creating a perfused vasculature that responds to stimuli similarly to native vessels.

**Methods:** Sacrificial loops with a diameter of 750 μm were designed using Fusion 360 3D-modeling software and 3D printed with PVA filament. The loops were soaked in 70% ethanol for 15 minutes and dried for 30 minutes. They were then enclosed in 1% (w/v) type I collagen and cultured with sterile PBS at 37°C for 48 hours, followed by flushing the channel with 40 mL PBS to remove residual PVA. The hollow pre-formed channel was lined with a layer of human aortic smooth muscle cells (HASMs) and subsequently with E4 endothelial cells (EC). To mimic blood flow, the construct was perfused using a peristaltic pump for 5 days. Perfusion was started at 2.92 dyne/cm² and increased daily by 0.66 dyne/cm² to prevent cell dislodgement.

**Key Results:** The sacrificial loops were successfully designed with a 750 μm diameter. Unlike some previously published sacrificial materials that quickly dissolve upon contact with liquid and cannot be sterilized with ethanol, PVA could be submerged in 70% ethanol for 15 minutes without appreciable material degradation or structure loss. ECs incubated with an 8% PVA mixture over 72 hours did not experience significant cytotoxicity. Immunofluorescence revealed an elaborate blood vessel shape in the 3D printed structure robustly lined with complete smooth muscle cell (SMC) and EC layers. As early as 2 days after perfusion, ECs aligned and elongated in the direction of perfusion, comparable to physiologic flow changes.

**Clinical Implications:** This study demonstrates that PVA is a promising sacrificial material for creating perfused, intricate blood vessel structures with diameters as small as 750 μm. Its ability to be sterilized, biocompatibility, high 3D printability, and flexible mechanical properties overcome limitations of other materials like Pluronic F127 or needles. The successful formation of aligned endothelial and smooth muscle cell layers under flow suggests that this approach could be used to engineer larger tissue flaps with better nutrient perfusion, potentially reducing reliance on autologous donor tissue in reconstructive surgery. Further studies are needed to assess long-term patency and integration with host vasculature.