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Soucy P.A.,Johns Hopkins University | Werbin J.,Johns Hopkins University | Heinz W.,Intelligent Substrates Inc. | Hoh J.H.,Johns Hopkins University | Romer L.H.,Johns Hopkins University
Acta Biomaterialia | Year: 2011

The mechanical properties of the extracellular microenvironment regulate cell behavior, including migration, proliferation and morphogenesis. Although the elastic moduli of synthetic materials have been studied, little is known about the properties of naturally produced extracellular matrix. Here we have utilized atomic force microscopy to characterize the microelastic properties of decellularized cell-derived matrix from human pulmonary fibroblasts. This heterogeneous three-dimensional matrix had an average thickness of 5 ± 0.4 μm and a Young's modulus of 105 ± 14 Pa. Ascorbate treatment of the lung fibroblasts prior to extraction produced a twofold increase in collagen I content, but did not affect the stiffness of the matrices compared with matrices produced in standard medium. However, fibroblast-derived matrices that were crosslinked with glutaraldehyde demonstrated a 67% increase in stiffness. This work provides a microscale characterization of fibroblast-derived matrix mechanical properties. An accurate understanding of native three-dimensional extracellular microenvironments will be essential for controlling cell responses in tissue engineering applications. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Source

Soucy P.A.,Johns Hopkins University | Soucy P.A.,University of Louisville | Hoh M.,Intelligent Substrates Inc. | Heinz W.,Intelligent Substrates Inc. | And 3 more authors.
Acta Biomaterialia | Year: 2015

Detailed control over the structural organization of scaffolds and engineered tissue constructs is a critical need in the quest to engineer functional tissues using biomaterials. This work presents a new approach to spatially direct endothelial tubulogenesis. Micropatterned fibronectin substrates were used to control lung fibroblast adhesion and growth and the subsequent deposition of fibroblast-derived matrix during culture. The fibroblast-derived matrix produced on the micropatterned substrates was tightly oriented by these patterns, with an average variation of only 8.5°. Further, regions of this oriented extracellular matrix provided directional control of developing endothelial tubes to within 10° of the original micropatterned substrate design. Endothelial cells seeded directly onto the micropatterned substrate did not form tubes. A metric for matrix anisotropy showed a relationship between the fibroblast-derived matrix and the endothelial tubes that were subsequently developed on the same micropatterns with a resulting aspect ratio over 1.5 for endothelial tubulogenesis. Micropatterns in "L" and "Y" shapes were used to direct endothelial tubes to turn and branch with the same level of precision. These data demonstrate that anisotropic fibroblast-derived matrices instruct the alignment and shape of endothelial tube networks, thereby introducing an approach that could be adapted for future design of microvascular implants featuring organ-specific natural matrix that patterns microvascular growth. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Source

Heinz W.F.,Intelligent Substrates Inc. | Hoh M.,Intelligent Substrates Inc.
Lab on a Chip - Miniaturisation for Chemistry and Biology | Year: 2011

Protein micropatterned substrates have emerged as important tools for studying how cells interact with their environment, as well as allowing useful experimental control over, for example, cell shape and cell position on a surface. Here we present a new approach for protein micropatterning in which a focused laser is used to locally inactivate proteins on a protein-coated substrate. By translating the laser relative to the substrate, protein patterns of essentially arbitrary shape can be produced. This approach has a number of useful features. To begin, it is a maskless writing approach. Thus new patterns can be designed and implemented quickly. Laser inactivation can also be performed on a number of different substrate materials, ranging from glass to polydimethylsiloxane. Further, the inactivation is dose dependent, thus complex gradients and other non-uniform distributions of proteins can be produced. Because the focus of the laser can be changed quickly, laser-based patterning can also be applied to substrates with complex topographies or enclosed surfaces - as long as an optical path is available. To demonstrate this capability, protein patterns were made on the inside of small quartz capillary tubes. Patterned substrates produced using laser inactivation constrain cell shape in predictable ways, and we show that these substrates are compatible with a number of different eukaryotic cell lines. © 2011 The Royal Society of Chemistry. Source

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