Nanostructuring PEG-fibrinogen hydrogels to control cellular morphogenesis.

The nanostructuring of hydrogel scaffolds used in tissue engineering aims to provide an ability to control cellular morphogenesis through defined cell-matrix interactions. Toward this objective, we developed a method that alters the molecular network structure of biosynthetic hydrogel scaffolds made from crosslinked poly(ethylene glycol)-fibrinogen conjugates (PEG-fibrinogen, PF). The modifications were based on Pluronic(®) F127 micelles that were formed in the hydrogel precursor solution and that altered the hydrogel network assembly during photopolymerization crosslinking. Two variations of the cell-encapsulating hydrogels (high and low crosslinking density) were prepared with three concentrations of Pluronic(®) F127 (3%, 7%, 10% w/v). Quantitative morphometrics were used to characterize fibroblast shape parameters (both transient and stable) in all hydrogels, and rheological characterizations were used to measure the elastic (storage) component of the complex shear modulus of these hydrogels. The morphometric data was then correlated to both the nanostructure and modulus of the hydrogels for day 1 and day 4 in culture. These correlations revealed that structural features imparted by the Pluronic(®) F127 micelles were able to reverse the normally strong correlations found between indicators of cell spreading and the hydrogel's mechanical properties. Therefore, the data supports the conclusion that nanostructural features in the encapsulating hydrogel culture environment can facilitate better cell spreading in a dense hydrogel milieu, simply by introducing imperfections into the network structure. This research also provides further prospective regarding biocompatible approaches toward making structural modifications to hydrogel scaffolds for the purpose of 3-D cell culture and tissue engineering.

[1]  D. Soll,et al.  Phosphorylation of the Dictyostelium myosin II heavy chain is necessary for maintaining cellular polarity and suppressing turning during chemotaxis. , 1998, Cell motility and the cytoskeleton.

[2]  H. Bianco-Peled,et al.  Nanostructuring of PEG-fibrinogen polymeric scaffolds. , 2010, Acta biomaterialia.

[3]  D. Seliktar,et al.  Biological and mechanical implications of PEGylating proteins into hydrogel biomaterials. , 2011, Biomaterials.

[4]  Seeram Ramakrishna,et al.  Biomimetic electrospun nanofibers for tissue regeneration , 2006, Biomedical materials.

[5]  Antonios G Mikos,et al.  Biomimetic materials for tissue engineering. , 2003, Biomaterials.

[6]  Chain extension as a strategy for the development of improved reverse thermo-responsive polymers† , 2007 .

[7]  Jackie Y Ying,et al.  Nanomaterials for in situ cell delivery and tissue regeneration. , 2010, Advanced drug delivery reviews.

[8]  E. Wolvetang,et al.  A synthetic elastomer based on acrylated polypropylene glycol triol with tunable modulus for tissue engineering applications. , 2010, Biomaterials.

[9]  Peter Friedl,et al.  Cell migration strategies in 3‐D extracellular matrix: Differences in morphology, cell matrix interactions, and integrin function , 1998, Microscopy research and technique.

[10]  Jennifer L. West,et al.  Synthetic Materials in the Study of Cell Response to Substrate Rigidity , 2009, Annals of Biomedical Engineering.

[11]  C. McCulloch,et al.  The compliance of collagen gels regulates transforming growth factor-β induction of α-smooth muscle actin in fibroblasts , 1999 .

[12]  Laura A. Smith,et al.  Nanostructured polymer scaffolds for tissue engineering and regenerative medicine. , 2009, Wiley interdisciplinary reviews. Nanomedicine and nanobiotechnology.

[13]  S. Bryant,et al.  Cell encapsulation in biodegradable hydrogels for tissue engineering applications. , 2008, Tissue engineering. Part B, Reviews.

[14]  David J. Mooney,et al.  Growth Factors, Matrices, and Forces Combine and Control Stem Cells , 2009, Science.

[15]  C. McCulloch,et al.  The compliance of collagen gels regulates transforming growth factor-beta induction of alpha-smooth muscle actin in fibroblasts. , 1999, The American journal of pathology.

[16]  A. Metters,et al.  Synthetic matrix metalloproteinase-sensitive hydrogels for the conduction of tissue regeneration: Engineering cell-invasion characteristics , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[17]  Jason A. Burdick,et al.  Controlling Stem Cell Fate with Material Design , 2010, Advanced materials.

[18]  Sanjay Kumar,et al.  The mechanical rigidity of the extracellular matrix regulates the structure, motility, and proliferation of glioma cells. , 2009, Cancer research.

[19]  H. Bianco-Peled,et al.  The effect of structural alterations of PEG-fibrinogen hydrogel scaffolds on 3-D cellular morphology and cellular migration. , 2006, Biomaterials.

[20]  J. Hubbell,et al.  Part II: Fibroblasts preferentially migrate in the direction of principal strain , 2008, Biomechanics and modeling in mechanobiology.

[21]  D. Seliktar,et al.  Matrix stiffness affects spontaneous contraction of cardiomyocytes cultured within a PEGylated fibrinogen biomaterial. , 2007, Acta biomaterialia.

[22]  K J Gooch,et al.  The relative magnitudes of endothelial force generation and matrix stiffness modulate capillary morphogenesis in vitro. , 2004, Experimental cell research.

[23]  John W Haycock,et al.  3D cell culture: a review of current approaches and techniques. , 2011, Methods in molecular biology.

[24]  D. Seliktar,et al.  Biosynthetic hydrogel scaffolds made from fibrinogen and polyethylene glycol for 3D cell cultures. , 2005, Biomaterials.

[25]  Adam J. Engler,et al.  Matrix elasticity directs stem cell differentiation , 2006 .

[26]  Daniel Cohn,et al.  Improved reverse thermo-responsive polymeric systems. , 2003, Biomaterials.

[27]  C. Murphy,et al.  Epithelial contact guidance on well-defined micro- and nanostructured substrates , 2003, Journal of Cell Science.

[28]  P. Janmey,et al.  Tissue Cells Feel and Respond to the Stiffness of Their Substrate , 2005, Science.

[29]  David J. Mooney,et al.  Harnessing Traction-Mediated Manipulation of the Cell-Matrix Interface to Control Stem Cell Fate , 2010, Nature materials.

[30]  Mikaël M. Martino,et al.  Biomimetic materials in tissue engineering , 2010 .

[31]  Kristi S Anseth,et al.  Materials science. Hydrogel cell cultures. , 2007, Science.

[32]  Casey K. Chan,et al.  Degradation of electrospun nanofiber scaffold by short wave length ultraviolet radiation treatment and its potential applications in tissue engineering. , 2008, Tissue engineering. Part A.

[33]  John A. Pedersen,et al.  Mechanobiology in the Third Dimension , 2005, Annals of Biomedical Engineering.

[34]  H. Bianco-Peled,et al.  Defining the role of matrix compliance and proteolysis in three-dimensional cell spreading and remodeling. , 2008, Biophysical journal.

[35]  K. Anseth,et al.  Hydrogel Cell Cultures , 2007, Science.

[36]  S. Sen,et al.  Matrix Elasticity Directs Stem Cell Lineage Specification , 2006, Cell.

[37]  D. Seliktar,et al.  Protein-polymer conjugates for forming photopolymerizable biomimetic hydrogels for tissue engineering. , 2007, Biomaterials.

[38]  J. Hubbell,et al.  Synthetic biomaterials as instructive extracellular microenvironments for morphogenesis in tissue engineering , 2005, Nature Biotechnology.