Biomaterials functionalized with nanoclusters of integrin- and syndecan-binding ligands improve cell adhesion and mechanosensing under shear flow conditions

REDV-Functionalized Recombinant Spider Silk for Next-Generation Coronary Artery Stent Coatings: Hemocompatible, Drug-Eluting, and Endothelial Cell-Specific Materials

Coronary artery stents are life-saving devices, and millions of these devices are implanted annually to treat coronary heart disease. The current gold standard in treatment is drug-eluting stents, which are coated with a biodegradable polymer layer that elutes antiproliferative drugs to prevent restenosis due to neointimal hyperplasia. Stenting is commonly paired with systemic antiplatelet therapy to prevent stent thrombosis. Despite their clinical success, current stents have significant limitations including inducing local inflammation that drives hyperplasia; a lack of hemocompatibility that promotes thrombosis, increasing need for antiplatelet therapy; and limited endothelialization, which is a critical step in the healing process. In this research, we designed a novel material for use as a next-generation coating for drug-eluting stents that addresses the limitations described above. Specifically, we developed a recombinant spider silk material that is functionalized with an REDV cell-adhesive ligand, a peptide motif that promotes specific adhesion of endothelial cells in the cardiovascular environment. We illustrated that this REDV-modified spider silk variant [eADF4(C16)-REDV] is an endothelial-cell-specific material that can promote the formation of a near-confluent endothelium. We additionally performed hemocompatibility assays using human whole blood and demonstrated that spider silk materials exhibit excellent hemocompatibility under both static and flow conditions. Furthermore, we showed that the material displayed slow enzyme-mediated degradation. Finally, we illustrated the ability to load and release the clinically relevant drug everolimus from recombinant spider silk coatings in a quantity and at a rate similar to that of commercial devices. These results support the use of REDV-functionalized recombinant spider silk as a coating for drug-eluting stents.

Emerging biomaterials and technologies to control stem cell fate and patterning in engineered 3D tissues and organoids

The ability to create complex three-dimensional cellular models that can effectively replicate the structure and function of human organs and tissues in vitro has the potential to revolutionize medicine. Such models could facilitate the interrogation of developmental and disease processes underpinning fundamental discovery science, vastly accelerate drug development and screening, or even be used to create tissues for implantation into the body. Realization of this potential, however, requires the recreation of complex biochemical, biophysical, and cellular patterns of 3D tissues and remains a key challenge in the field. Recent advances are being driven by improved knowledge of tissue morphogenesis and architecture and technological developments in bioengineering and materials science that can create the multidimensional and dynamic systems required to produce complex tissue microenvironments. In this article, we discuss challenges for in vitro models of tissues and organs and summarize the current state-of-the art in biomaterials and bioengineered systems that aim to address these challenges. This includes both top-down technologies, such as 3D photopatterning, magnetism, acoustic forces, and cell origami, as well as bottom-up patterning using 3D bioprinting, microfluidics, cell sheet technology, or composite scaffolds. We illustrate the varying ways that these can be applied to suit the needs of different tissues and applications by focussing on specific examples of patterning the bone-tendon interface, kidney organoids, and brain cancer models. Finally, we discuss the challenges and future prospects in applying materials science and bioengineering to develop high-quality 3D tissue structures for in vitro studies.

Syndecan-4 promotes vascular beds formation in tissue engineered liver via thrombospondin 1

Instantaneous blood coagulation after bioengineered liver transplantation is a major issue, and the key process in its prevention is the construction of the endothelial vascular bed on biomimetic scaffolds. However, the specific molecules involved in the regulation of the vascular bed formation remain unclear. Syndecan-4 is a type I transmembrane glycoprotein commonly expressed in the human body; its receptor has been reported as critical for optimal cell adhesion and initiation of intracellular signaling, indicating its promising application in vascular bed formation. In the current study, bioinformatics analysis and in vitro experiments were performed to evaluate whether syndecan-4 promoted endothelial cell migration and functional activation. Exogenous syndecan-4-overexpressing endothelial cells were perfused into the decellularized liver scaffold, which was assessed by Masson’s trichrome staining. Western blotting and qRT-PCR were used to evaluate the effects of syndecan-4 on the thrombospondin 1 (THBS1) stability. We found that syndecan-4 promoted the adhesion of vascular endothelial cells and facilitated cell migration and angiogenesis. Furthermore, syndecan-4 overexpression resulted in a well-aligned endothelium on the decellularized liver scaffolds. Mechanistically, syndecan-4 destabilized THBS1 at the protein level. Therefore, our data revealed that syndecan-4 promoted the biological activity of endothelial cells on the bionic liver vascular bed through THBS1. These findings provide scientific evidences for solving transient blood coagulation after bionic liver transplantation.