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Cardiovascular surgery continues to face a shortage of suitable biomaterials for full-vessel bypass procedures and vascular patch repair. Current materials exhibit several limitations, including poor patency in small-diameter vessels, limited remodeling capacity, and a high risk of thrombosis [1]. While PLCL (poly(L-lactide-co-ε-caprolactone)) nanofiber sheets are biodegradable over several months, their mechanical properties—particularly suture retention—are insufficient for direct use as patching materials.
However, these sheets serve as an excellent sacrificial substrate for printing collagen-based scaffolds embedded with cells, offering a promising platform for tissue remodeling. In this study, we aimed to develop tissue-engineered vascular patches using PLCL nanofiber carriers combined with printed collagen scaffolds encapsulating adipose-derived stromal cells (ASCs) or smooth muscle cells (SMCs). The constructs were matured in a bioreactor and subsequently decellularized using a custom-built automated system.
PLCL nanofiber sheets were cut into 26 × 76 mm rectangles to fit a custom vacuum fixture in our extrusion-based bioprinter. We employed an optimized collagen bioink at a concentration of 30 mg/mL, incorporating ASCs and SMCs [2]. The bioink was printed onto the PLCL sheets in a rectangular pattern (up to 50 × 20 mm) with a total thickness of 1.5 mm, using 0.25 mm layer increments.
The printed constructs were mounted in a custom-designed bioreactor chamber and connected to a pulsatile flow generator delivering up to 80 mL/min at pressures of 120/60 mmHg. These parameters were selected to generate shear stress up to 10 dyn/cm², promoting cell proliferation, differentiation, and extracellular matrix (ECM) formation [3]. After 7 days of dynamic cultivation, the samples were harvested.
To minimize immunogenicity, the constructs underwent decellularization using our automated system, which performs cycle-based decellularization with integrated rinsing and washing. The process involved four 20-minute cycles with 1% SDS, followed by extensive rinsing—six 10-minute cycles and twenty-three 1-hour cycles [1,3].
Scanning electron microscopy (SEM) confirmed the formation of ECM microstructures resembling native vascular tissue [1]. Mechanical testing revealed a significant improvement in strength compared to unmodified PLCL sheets. However, suture retention remains suboptimal in some samples for in vivo applications. Ongoing optimization efforts focus on crosslinking and mesh reinforcement to enhance mechanical stability.
Nevertheless, the structure developed through this approach demonstrates promising potential as a tissue-engineered vascular patch.
This research was funded by the Ministry of Health of the Czech Republic grant No. NW24-08-00064 and NW24J-02-00061 and by the Grant Agency of the Czech Technical University in Prague (grant No. SGS25/183/OHK4/3T/17).
[1] Chlupac, J.; Matejka, R.; et al. Vascular Remodeling of Clinically Used Patches and Decellularized Pericardial Matrices Recellularized with Autologous or Allogeneic Cells in a Porcine Carotid Artery Model. Int. J. Mol. Sci. 2022, 23, 3310.
[2] Matejkova, J.; Kanokova, D.; Supova, M.; Matejka, R. A New Method for the Production of High-Concentration Collagen Bioinks with Semiautonomic Preparation. Gels 2024, 10, 66.
[3] Matějka, R.; Koňařík, M.; Štěpanovská, J.; et al. Bioreactor Processed Stromal Cell Seeding and Cultivation on Decellularized Pericardium Patches for Cardiovascular Use. Appl. Sci. 2020, 10, 5473.
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