The Potential of Protein Functionalized Electrospun Scaffolds for Heart Valve Engineering
Svenja Hinderer1, Andrea Kulessa2, Katja Schenke-Layland1.
1Fraunhofer IGB, Stuttgart, Germany, 2University of Tübingen, Tübingen, Germany.
Objective: Currently available heart valve replacements are limited in long-term performance or fail due to lack of growth or remodeling potential. In order to address these issues, it is necessary to mimic multiple factors of the native valvular extracellular matrix (ECM) such as architecture, mechanical behavior and biochemical signals. Electrospinning is a suitable method to mimic the fibrous structure of the ECM. For an easy translation into clinics, cell-free products with the potential of self-seeding are preferable. We aimed to generate a nature-mimicking 2-layered scaffold via electrospinning and protein coating, which is able to bind circulating stem or progenitor cells from blood.
Methods: A polymeric scaffold was generated via electrospinning based on the structural and mechanical characteristics of native heart valve leaflets. After specific protein coating, the scaffolds were dynamically cultured on a shaker with a suspension of endothelial progenitor cells (EPCs). Uncoated scaffolds served as the control. Protein-mediated cell adhesion was determined using SEM and DAPI staining. EPC viability was assessed with imaging flow cytometry analysis. Furthermore, immunostaining was used in order to visualize native ECM as well as scaffold bound protein and to characterize adhered EPCs on the scaffolds.
Results: We successfully generated a biocompatible polymeric scaffold via electrospinning, which showed similar structural and mechanical properties as porcine heart valve leaflets. The mechanical performance of the scaffold was successfully tested in a heart valve bioreactor, which mimics physiological conditions. Despite the high hydrophilicity, it was possible to functionalize the surface with several proteins. After a 2 day dynamic culture of circulating EPCs in suspension, a significantly higher number of EPCs were detected on the coated scaffolds when compared to uncoated controls. Furthermore, immunostaining confirmed CXCR4, VEGFR2, vWF and CD34 positive cells before and after substrate contact.
Conclusions: We successfully demonstrated that specific proteins are important to enable EPC adhesion and therefore excellent for the functionalization of the tissue engineered heart valve. The generated nature-mimicking polymeric scaffold coated with various proteins is a promising off-the-shelf material with cell-capturing potential.
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