Biomimetic strategy towards gelatin coatings on PET. Effect of protocol on coating stability and cell-interactive properties

3D Printed Tubulointerstitium Chip as an In Vitro Testing Platform

Chronic kidney disease (CKD) ranks as the twelfth leading cause of death worldwide with limited treatment options. The development of in vitro models replicating defined segments of the kidney functional units, the nephrons, in a physiologically relevant and reproducible manner can facilitate drug testing. The aim of this study was to produce an in vitro organ-on-a-chip platform with extrusion-based three-dimensional (3D) printing. The manufacturing of the tubular platform was produced by printing sacrificial fibers with varying diameters, providing a suitable structure for cell adhesion and proliferation. The chip platform was seeded with primary murine tubular epithelial cells and human umbilical vein endothelial cells. The effect of channel geometry, its reproducibility, coatings for cell adhesion, and specific cell markers were investigated. The developed chip presents single and dual channels, mimicking segments of a renal tubule and the capillary network, together with an extracellular matrix gel analogue placed in the middle of the two channels, envisioning the renal tubulointerstitium in vitro. The 3D printed platform enables perfusable circular cross-section channels with fully automated, rapid, and reproducible manufacturing processes at low costs. This kidney tubulointerstitium on-a-chip provides the first step toward the production of more complex in vitro models for drug testing.

Bioinspired, Artificial, Small-Diameter Vascular Grafts with Selective and Rapid Endothelialization Based on an Amniotic Membrane-Derived Hydrogel

Clinical application of the amniotic membrane (AM) in vascular reconstruction was limited by poor processability, rapid biodegradation, and insufficient hemocompatibility. In this work, decellularized AM was digested to a thermosensitive hydrogel and densely cross-linked in the nanoscale as "enhanced" collagenous fibers. Via N-(3-dimehylaminopropyl)-N'-ethylcarbodiimide and N-hydroxysuccinimide (EDC/NHS) catalysis, REDV was further grafted to simulate anticoagulant substances on naturally derived blood vessels. This modification approach endowed AM with rapid endothelialization and rare vascular restenosis. Through adjusting the fixation condition, the pore size and mechanical stability of the fiber network were approximate to those of natural tissues and precisely designed to fit for cell adhesion. AM was synchronously fixed by alginate dialdehyde (ADA) and EDC/NHS, forming a "double-cross-linked" stable structure with significantly improved mechanical strength and resistance against enzymic degradation. The hemolytic and platelet adhesion test indicated that ADA/REDV-AM could inhibit hemolysis and coagulation. It also exhibited excellent cytocompatibility. It selectively accelerated adsorption and migration of endothelial cells (ECs) while impeding adhesion and proliferation of smooth muscle cells (SMCs). It maintained EC superiority in competitive growth and avoided thrombosis in vivo. Furthermore, its property of promoting reconstruction and repair of blood vessels was proved in an animal experiment. Overall, the present study demonstrates that ADA/REDV-AM has potential application as a small-diameter artificial vascular intima with rapid endothelialization and reduced SMC/platelet adhesion.