Peptide-Functionalized Electrospun Meshes for the Physiological Cultivation of Pulmonary Alveolar Capillary Barrier Models in a 3D-Printed Micro-Bioreactor

In vitro environments that realize biomimeticscaffolds, cellular composition, physiological shear, and strain areintegral to developing tissue models of organ-specific functions.In this study, an in vitro pulmonary alveolar capillarybarrier model is developed that closely mimics physiological functionsby combining a synthetic biofunctionalized nanofibrous membrane systemwith a novel three-dimensional (3D)-printed bioreactor. The fibermeshes are fabricated from a mixture of polycaprolactone (PCL), 6-armedstar-shaped isocyanate-terminated poly(ethylene glycol) (sPEG-NCO),and Arg-Gly-Asp (RGD) peptides by a one-step electrospinning processthat offers full control over the fiber surface chemistry. The tunablemeshes are mounted within the bioreactor where they support the co-cultivationof pulmonary epithelial (NCI-H441) and endothelial (HPMEC) cell monolayersat air-liquid interface under controlled stimulation by fluidshear stress and cyclic distention. This stimulation, which closelymimics blood circulation and breathing motion, is observed to impactalveolar endothelial cytoskeleton arrangement and improve epithelialtight junction formation as well as surfactant protein B productioncompared to static models. The results highlight the potential ofPCL-sPEG-NCO:RGD nanofibrous scaffolds in combination with a 3D-printedbioreactor system as a platform to reconstruct and enhance in vitro models to bear a close resemblance to invivo tissues.