Interactions between Spider Silk and Cells – NIH/3T3 Fibroblasts Seeded on Miniature Weaving Frames

Native spider silk does not require any modification to its application as a biomaterial that can rival any artificial material in terms of cell growth promoting properties. We could show adhesion mechanics on intracellular level. Additionally, proliferation kinetics were higher than in enzymatically digested controls, indicating that spider silk does not require modification. Recent findings concerning reduction of cell proliferation after exposure could not be met. As biotechnological production of the hierarchical composition of native spider silk fibres is still a challenge, our study has a pioneer role in researching cellular mechanics on native spider silk fibres

Efficient differentiation of CD14(+) monocytic cells into endothelial cells on degradable biomaterials

Vascular tissue engineering aims at creating self-renewing, anti-thrombogenic, vascular grafts, which can be based on endothelial progenitor cells (EPC). EPC harbor essential features such as plasticity and longevity. Unfortunately, the archetype CD34+ EPC is rare in peripheral blood. Monocytes, i.e. CD14+ cells also have the ability to differentiate into endothelial-like cells and are by far more abundant in peripheral blood than are CD34+ EPC. Therefore, CD14+ cells would seem appropriate candidates for tissue engineering of small-diameter blood vessels. In this study, we investigated the differentiation of CD14+ cells on three biodegradable biomaterials under angiogenic conditions. Morphological analyses, gene transcript analyses, endothelial marker (i.e. VE-Cadherin and eNOS) and macrophage marker (i.e. CD68 and CD163) expression analyses, revealed that a small fraction (15-25%) of cultured CD14+ cells differentiated into macrophages after 21 days of culture. The majority of CD14+ cells (>75%) differentiated into endothelial-like cells (ELC) on all biomaterials used. The expression of endothelial markers was similar to their expression on HUVEC. Since CD14+ cells are present in high numbers in adult peripheral blood, easy to isolate and because they easily differentiate into ELC on biomaterials, we conclude that CD14+ cells are a suitable cell source for progenitor-based vascular tissue engineering

Characterization and biocompatibility of epoxy-crosslinked dermal sheep collagens

Dermal sheep collagen (DSC), which was crosslinked with 1,4-butanediol diglycidyl ether (BD) by using four different conditions, was characterized and its biocompatibility was evaluated after subcutaneous implantation in rats. Crosslinking at pH 9.0 (BD90) or with successive epoxy and carbodiimide steps (BD45EN) resulted in a large increase in the shrinkage temperature (Ts) in combination with a clear reduction in amines. Crosslinking at pH 4.5 (BD45) increased the Ts of the material but hardly reduced the number of amines. Acylation (BD45HAc) showed the largest reduction in amines in combination with the lowest Ts. An evaluation of the implants showed that BD45, BD90, and BD45EN were biocompatible. A high influx of polymorphonuclear cells and macrophages was observed for BD45HAc, but this subsided at day 5. At week 6 the BD45 had completely degraded and BD45HAc was remarkably reduced in size, while BD45EN showed a clear size reduction of the outer DSC bundles; BD90 showed none of these features. This agreed with the observed degree of macrophage accumulation and giant cell formation. None of the materials calcified. For the purpose of soft tissue replacement, BD90 was defined as the material of choice because it combined biocompatibility, low cellular ingrowth, low biodegradation, and the absence of calcification with fibroblast ingrowth and new collagen formation

Chemical and biological properties of supramolecular polymer systems based on oligocaprolactones

We show that materials with a diverse range of mechanical and biological properties can be obtained using a modular approach by simply mixing different ratios of oligocaprolactones that are either end-functionalized or chain-extended with quadruple hydrogen bonding ureido-pyrimidinone (UPy) moieties. The use of two UPy-synthons allows for easy synthesis of UPy-modified polymers resulting in high yields. Comparison of end-functionalized UPy-polymers with chain-extended UPy-polymers shows that these polymers behave distinctively different regarding their material and biological properties. The end-modified UPy-polymer is rather stiff and brittle due to its high crystallinity. Disks made of this material fractures after subcutaneous implantation. The material shows a low inflammatory response which is accompanied by the formation of a fibrous capsule, reflecting the inertness of the material. The chain-extended UPy-material on the contrary is practically free of crystalline domains and shows clear flexible properties. This material deforms after in-vivo implantation, accompanied with cellular infiltration. By mixing both polymers, materials with intermediate properties concerning their mechanical and biological behaviour can be obtained. Surprisingly, a 20:80 mixture of both polymers with the chain-extended UPy-polymer in excess shows flexible properties without visible deformation upon implantation for 42 days. This mixture, a blend formed by intimate mixing through UPy-UPy interaction, also shows a mild tissue response accompanied with the formation of a thin capsule. The material does not become more crystalline upon implantation. Hence, this mixture might be an ideal scaffold material for soft tissue engineering due to its flexibility and diminished fibrous tissue formation, and illustrates the strength of the modular approach. (c) 2006 Elsevier Ltd. All rights reserved

Bioengineering of living renal membranes consisting of hierarchical, bioactive supramolecular meshes and human tubular cells

Maintenance of polarisation of epithelial cells and preservation of their specialized phenotype are great challenges for bioengineering of epithelial tissues Mimicking the basement membrane and underlying extracellular matrix (ECM) with respect to its hierarchical fiber-like morphology and display of bioactive signals is prerequisite for optimal epithelial cell function in vitro We report here on a bottom-up approach based on hydrogen-bonded supramolecular polymers and ECM-peptides to make an electro-spun bioactive supramolecular mesh which can be applied as synthetic basement membrane The supramolecular polymers used self-assembled into nano-meter scale fibers while at micro-meter scale fibers were formed by electro-spinning We introduced bioactivity into these nano-fibers by intercalation of different ECM-peptides designed for stable binding Living kidney membranes were shown to be bioengineered through culture of primary human renal tubular epithelial cells on these bioactive meshes Even after a long-term culturing period of 19 days we found that the cells on bioactive membranes formed tight monolayers while cells on non-active membranes lost their monolayer integrity Furthermore the bioactive membranes helped to support and maintain renal epithelial phenotype and function Thus incorporation of ECM-peptides Into electro-spun meshes via a hierarchical supramolecular method is a promising approach to engineer bioactive synthetic membranes with an unprecedented structure This approach may in future be applied to produce living bioactive membranes for a I:no-artificial kidney (C) 2010 Elsevier Ltd All rights reserve