Cellular response to phase‐separated blends of tyrosine‐derived polycarbonates

Abstract

Two-dimensional thin films consisting of homopolymer and discrete compositional blends of tyrosine-derived polycarbonates were prepared and characterized in an effort to elucidate the nature of different cell responses that were measured in vitro. The structurally similar blends were found to phase separate after annealing with domain sizes dependent on the overall composition. The thin polymer films were characterized with the use of atomic force microscopy (AFM), water contact angles, and time-of-flight secondary ion mass spectrometry (TOF-SIMS) and significant changes in roughness were measured following the annealing process. Genetic expression profiles of interleukin-1β and fibronectin in MC3T3-E1 osteoblasts and RAW 264.7 murine macrophages were measured at several time points, demonstrating the time and composition-dependent nature of the cell responses. Real-time reverse transcriptase polymerase chain reaction (RT-PCR) depicted upregulation of the fibronectin gene copy numbers in each of the blends relative to the homopolymers. Moreover, the interleukin-1β expression profile was found to be compositionally dependent. The data suggest strongly that optimal composition and processing conditions can significantly affect the acute inflammatory and extracellular matrix production responses.

Combinatorial Polymer Scaffold Libraries for Screening Cell‐Biomaterial Interactions in 3D

“…[21,22] The variation of these properties also affected gene expression in osteoblast and macrophage cell lines cultured on films of the polymers and their blends. [21] These results indicate that the pDTEc/pDTOc system will elicit differences in cell behavior and will make a good test system for the combinatorial scaffold-library approach.…”

“…The different chemical and physical properties of pDTEc and pDTOc (different side chains, surface energy, glass transition temperatures, mechanical properties, and degradation rate) [21,22] may contribute to the differences in cell response observed in the scaffold libraries. These differences in material properties can also affect the adsorption of serum proteins to the materials, which can contribute to the observed differences in cell response.…”

“…pDTEc and pDTOc have different water contact angles (718 for pDTEc and 918 for pDTOc), glass transition temperatures (99 8C for pDTEc and 53 8C for pDTOc), mechanical properties (pDTEc is brittle (4% elongation at break), while pDTOc is ductile (400% elongation at break)), and degradation rates (pDTEc degrades faster). [21,22] The respective properties affected cell response causing enhanced cell spreading, adhesion, and proliferation on films of pDTEc versus pDTOc during in vitro cell-culture experiments. [21,22] The variation of these properties also affected gene expression in osteoblast and macrophage cell lines cultured on films of the polymers and their blends.…”

“…[21,22] The respective properties affected cell response causing enhanced cell spreading, adhesion, and proliferation on films of pDTEc versus pDTOc during in vitro cell-culture experiments. [21,22] The variation of these properties also affected gene expression in osteoblast and macrophage cell lines cultured on films of the polymers and their blends.[21]These results indicate that the pDTEc/pDTOc system will elicit differences in cell behavior and will make a good test system for the combinatorial scaffold-library approach.Another reason for our interest in testing these two polymers is that tyrosine-derived polymers have successfully been used …”

“…[4][5][6][7][8][9][10][11] However, methods for screening cell-biomaterial interactions are mostly limited to 2D films or surfaces, [4][5][6][7][8][9][10][11][12][13][14] despite the facts that biomaterials are frequently used to fabricate 3D scaffolds, [15] cells exist in vivo in a 3D environment, and cells cultured in vitro in a 3D environment typically behave more physiologically than those cultured on a 2D surface. [16][17][18][19][20] Films and surfaces typically display a ''nanoscale'' roughness, [11,21] while processing of biomaterials into 3D scaffolds yields structures with a topographical roughness at multiple size scales. Cells are very sensitive to material topography and the large difference in structure between 2D films and 3D scaffolds should be considered when screening materials.…”