Jockenhoevel, S. | Search bioRxiv

bioRxiv2025

Evaluation of Tissue-Engineered Blood Vessels as Three-Dimensional In Vitro Testing System in Cardiovascular Research and Device Approval

BackgroundDisturbed crosstalk between endothelial cells (ECs) and vascular smooth muscle cells (SMCs) has an important role in atherosclerosis and restenosis after vascular intervention, however, the exact pathomechanisms are incompletely understood. Current preclinical testing models do not adequately recapitulate the complexity of human arteries. Here, we present tissue-engineered blood vessels (TEBVs) as a novel in vitro model and validate it for intimal hyperplasia. MethodsTEBVs fabricated from SMC suspended in fibrin gel, supported by a textile mesh, were seeded with ECs at various concentrations and subjected to arterial flow conditions in a bioreactor. In addition, TEBVs underwent plain old balloon angioplasty (POBA) and implantation of bare metal stents (BMS) and drug-eluting stents (DES) at day 7 after fabrication. TEBVs were dynamically conditioned in a bioreactor for 21 days in total and monitored by optical coherence tomography. ResultsTEBVs with absent or incomplete endothelial layer exhibited thicker vessel walls, more disorganized and misaligned collagen, and increased cellular proliferation compared with completely endothelialized TEBVs. POBA and stent implantation were feasible 7 days after TEBV fabrication. At 14 days post-intervention, POBA-treated TEBVs exhibited significantly thicker vessel walls than untreated controls and stented TEBVs, whereas stented TEBVs showed greater lumen diameters than unstented TEBVs. Endothelial strut coverage was significantly higher in BMS-treated compared with DES-treated TEBVs. Over the course of the conditioning period, levels of IL-6, IL-8, and MCP-1 were highest in medium samples from BMS-treated TEBVs compared to DES-treated TEBVs and compared to untreated controls. ConclusionsTEBVs are a promising approach towards an in vitro system for the study of intimal hyperplasia. Due to their similarity in size and wall thickness to human coronary arteries, TEBVs may also serve as a platform for testing new stent designs. Graphical AbstractTissue-engineered blood vessels (TEBV) fabricated from smooth muscle cell /fibroblast mixtures suspended in fibrin gel, supported by a textile mesh, were seeded with endothelial cells and conditioned in a bioreactor system for 21 days. Different endothelialization strategies resulted in differences in wall thickness. In addition, TEBVs underwent plain old balloon angioplasty (POBA) and stent implantation. POBA-treated TEBVs exhibited thicker vessel walls compared with non-treated TEBV controls and compared with stented TEBVs. We also observed significantly higher stent strut coverage with endothelial cells after implantation of bare metal stents (BMS) compared to drug-eluting stents (DES). TEBVs are a promising approach towards an in-vitro system for the study of intimal hyperplasia. Due to their similarity in size and wall thickness to human coronary arteries, TEBVs may also serve as a platform for testing new stent designs.

bioengineering↗

bioRxiv2023

Towards Biohybrid Lung Development? Inflammatory Conditions Disrupt Endothelial Layer Integrity on Gas Exchange Membranes

Systemic inflammation presents a significant challenge to the long-term function of biohybrid implants. While endothelialisation of biohybrid implants has been shown to improve device hemocompatibility, its feasibility under the influence of patients inflammatory status remains largely unexplored. To investigate this, we developed a controlled in vitro model which allows to study endothelial dysfunction under inflammatory stress. Endothelial cells were cultured on polydimethylsiloxane under physiological shear stress and exposed to lipopolysaccharide (LPS)-activated peripheral blood mononuclear cells (PBMCs), simulating inflammatory conditions. Endothelial morphology and confluence was assessed using immunohistochemistry and scanning electron microscopy. Leukocyte adhesion was evaluated directly as well as indirectly, using flow cytometry to analyse cell adhesion molecules. Quantitative PCR was used for gene expression analysis of inflammatory mediators. Notably, neither LPS nor PBMCs alone induced endothelial disruption, whereas their combination significantly impaired endothelial confluence: Inflammatory activation led to substantial loss of endothelial confluence, increased leukocyte adhesion, and elevated expression of adhesion molecules ICAM-1, VCAM-1, and E-selectin. Gene expression analysis highlights the upregulation of inflammatory mediators, such as IL-6, IL-8, IL-10, and MCP-1. This study underscores the challenges of implementing endothelialisation in biohybrid devices, particularly in patients with systemic inflammation. By considering translational hurdles, this work contributes to the development of clinically viable biohybrid constructs and highlights the importance of considering inflammatory dynamics when designing next-generation implants.

bioengineering↗