Piotr Paczos

The endothelialization of organ‐on‐chip platforms and vascular implants is often limited by slow cell attachment and unstable monolayer formation. This work presents a scalable workflow that imprints micro‐ and nano‐gratings into elastin‐like recombinamer (ELR)‐based hydrogels, enabling rapid endothelial cell capture and accelerating monolayer formation within 14 days. Three gelatin‐ELR formulations are engineered, with 1H‐NMR confirming incorporation of sequences designed to modulate bioactivity (ELR1: inert, ELR2: uPA‐responsive, ELR3: RGD‐adhesive). ELR incorporation generates fibrillar microstructures and enhances mechanical performance, yielding elastic‐dominant networks suitable for high‐fidelity pattern transfer. Using this library, the combined effects of ELR bioactivity and groove geometry on human iPSC‐derived endothelial cells are evaluated. In a 15‐min attachment assay, patterned ELR composites markedly improve cell retention compared to gelatin, with ELR2 on ∼350 and ∼4 µm grooves performing best, consistent with controlled, cell‐mediated interfacial remodeling. This early advantage persists, as ELR2 and ELR3 hydrogels support rapid alignment and reach confluence by day 14, whereas gelatin remains subconfluent. By combining enhanced early capture with protease‐regulated remodeling, ELR2 identifies a favorable design window. These results establish a materials design framework linking programmable ELR chemistry with surface topography to engineer endothelial interfaces, providing a versatile platform for vascular biomaterials and microphysiological systems.

Small-diameter vascular grafts that can grow with pediatric patients and resist thrombosis remain an unmet need, primarily due to slow and unstable endothelialization. Here, we engineer a tri-layer, human induced pluripotent stem cell (hiPSC)-derived vascular graft featuring a soft, patterned lumen. We introduce a scalable soft-lithography method to imprint longitudinal micro-grooves directly into the lumen of compliant hydrogel tubes, a key advance for cell-laden constructs. Computational fluid dynamics reveals that these grooves redistribute wall shear stress into protective low-shear valleys and aligning high-shear ridges without increasing the mean load. This engineered shear landscape, combined with a bioactive elastin-like recombinamer (ELR) hydrogel matrix, synergistically enhances hiPSC-endothelial cell (hiPSC-EC) capture and retention under perfusion. Patterned grafts accelerate the formation of confluent, axially aligned endothelial monolayers with mature VE-cadherin junctions, outperforming non-patterned controls. Concurrently, smooth muscle cells within the graft wall deposit extracellular matrix, driving time-dependent mechanical maturation. This platform provides a physiologically relevant model for vascular disease and a promising strategy for engineering growth-competent pediatric grafts.

The endothelialization of organ-on-chip platforms and vascular implants is often limited by slow cell attachment and unstable monolayer formation. This work presents a scalable workflow that imprints micro- and nano-gratings into elastin-like recombinamer (ELR)-based hydrogels, enabling rapid endothelial cell capture and accelerating monolayer formation within 14 days. Three gelatin-ELR formulations are engineered, with ¹H-NMR confirming incorporation of sequences designed to modulate bioactivity (ELR1: inert; ELR2: uPA-responsive; ELR3: RGD-adhesive). ELR incorporation generates fibrillar microstructures and enhances mechanical performance, yielding elastic-dominant networks suitable for high-fidelity pattern transfer and stable culture. Using this library, the combined effects of ELR bioactivity and groove geometry on human iPSC-derived endothelial cells (iPSC-ECs) are systematically evaluated. In a 15-minute attachment assay, patterned ELR composites markedly improve cell retention compared to gelatin, with ELR2 on ∼350 nm and ∼4 µm grooves performing best, consistent with controlled, cell-mediated interfacial remodeling. This early advantage persists, as ELR2 and ELR3 hydrogels support rapid alignment and reach confluence by day 14, whereas gelatin remains sub-confluent. Cytoskeletal analysis confirms F-actin alignment. By combining enhanced early capture with protease-regulated remodeling, ELR2 identifies a favorable design window. These results establish a materials design framework linking programmable ELR chemistry with surface topography to engineer endothelial interfaces, providing a versatile platform for vascular biomaterials and microphysiological systems.

The paper is devoted to the stability of cold-formed thin-walled profiles. The study includes geometric characteristics of various cross-sections such as closed rectangular profiles and C-shaped profiles with various types of stiffeners. It compares critical forces and stresses of various profile...