Cell-substrate interactions are important in many processes, including biocompatibility, marine biofouling, cell growth in culture, and cell separation. The influence of surface properties such as polarity, hydrophobic/hydrophilic or acid/base balance on cell interactions is poorly understood, however. In this study 2-hydroxyethyl methacrylate (HEMA) and ethyl methacrylate (EMA) in various volume ratios were copolymerized and spun cast onto glass to produce a chemically homologous series of surfaces varying principally in hydrophilicity. Growth, spreading, and attachment of mouse 3T3 cells were measured with time-lapse photomicroscopy, visualization of the nucleolus, and [3H]thymidine labeling, respectively. Fibronectin adsorption from serum to the copolymers was also measured, using 125I-labeled fibronectin. On all polymers made with monomers containing 50% or more EMA, cell numbers increased logarithmically with time at the same rate observed for glass (21-hr doubling time). Cells on 40% EMA polymers remained virtually constant in number while decreases in cell number were observed on all polymers made with 30% or less EMA. Attachment measured after either 2 or 20 hr was not well correlated with growth behavior since significant attachment occurred on polymers on which growth had not occurred. Spreading at 2 hr but especially after 24 hr was very similar to the variation in growth. The kinetics of attachment and spreading varied markedly among the copolymers. Fibronectin adsorption varied from 0.1 to 1.5 ng/cm2 on the copolymers and was similar to the variation in 2-hr spreading. Fibronectin adsorption from the serum and fibronectin exudation by the cells both appear to be important in determining 3T3 cell interactions with the HEMA-EMA copolymers. However, the relative influence of these two processes on cell behavior probably varies greatly among the copolymers. The interfacial properties of the copolymers which could account for a variation in the ability to support cell growth are discussed.

Hydrophilic-hydrophobic copolymers as cell substrates: Effect on 3T3 cell growth rates

The interaction of cells with solid surfaces is important in many settings, including the response of tissue to implanted materials. Protein adsorption to the surface plays a critical role in controlling cell interactions with surfaces. However, few comprehensive studies of both cell behavior and protein adsorption in complex protein mixtures (e.g., serum) have been done so the connection between these events is not well understood. In particular, methods to systematically perturb both protein adsorption and cell behavior in order to understand their relationship have been lacking. To induce changes in cell and protein behavior, the effects of serum dilution and substrate surface chemistry were studied. Surface chemistry was varied by using a series of polymers and copolymers of hydroxyethyl methacrylate (HEMA) and ethylmethacrylate (EMA) varying in their hydrophobic/hydrophilic balance. Large changes in cell spreading and fibronectin adsorption were observed when either serum concentration or polymer type was varied. The spreading of 3T3 cells in serum was found to be well correlated with the amount of fibronectin adsorption to the substrates. Attachment was not correlated with fibronectin adsorption, especially on glass preadsorbed with diluted serum. For 3T3 cells and perhaps other cells that have a receptor for a protein which is present in the medium, the amount of adsorption of this protein to the substrate appears to be a critical factor controlling cell interactions with the substrate.

Correlations between mouse 3T3 cell spreading and serum fibronectin adsorption on glass and hydroxyethylmethacrylate–ethylmethacrylate copolymers

A series of fluorine-containing segmented poly(ether urethanes) and poly(ether urethane ureas), previously characterized by angular dependent x-ray photoelectron spectroscopy (XPS) have been re-examined using static secondary ion mass spectrometry (SIMS). Comparison of the data from the two techniques has shown that the intensity of secondary ion signals which characterize the hard and soft segments can be used quantitatively for direct analyis of the molecular composition at the surface. Moreover, the SIMS sampling depth for the conditions used has been shown to be ∼ 10 A, significantly less than the XPS sampling depth under normal conditions, and similar to the XPS sampling depth at high glancing take-off angle (with respect to the surface normal).

SIMS and XPS studies of polyurethane surfaces 2. Polyurethanes with fluorinated chain extenders

Field-flow fractionation (FFF) is a family of flexible analytical fractionating techniques which have the great advantage that separation is achieved solely through the interaction of the sample with an external physical field and without a stationary phase. This has the advantage of avoiding the large variety of problems due to non-specific sample interactions with column materials associated with other chromatographic techniques. Furthermore, the range of information accessible is very broad and often complimentary when various FFF techniques are applied, so that even very complex systems with broad size distribution, heterogeneous mixtures or strongly interacting systems can be characterized. The range of particle sizes or hydrodynamic radii which can be separated is very broad ranging from 1 nm to 100 μm, covering the entire colloidal, polymeric and even most of the microparticle domain. No other fractionating technique can cover about 5 orders of magnitude of the particle size, even with complex distributions.

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Field-flow fractionation techniques for polymer and colloid analysis.

Contemporary topics in polymeric materials for biomedical applications are reviewed, with the emphasis on the modes of interaction of water soluble polymers as well as their conjugates, and those of microdomain-structured polymers with proteins and cells. The nature of biocompatibility of these polymer surfaces is discussed in terms of the random-network concept of water molecules on the polymer surface. Several recent studies on biohybridized and biomimicking materials are also reviewed.

Contemporary Topics in Polymeric Materials for Biomedical Applications

Differential retention of lymphocyte subpopulations (B and T cells) on the microphase separated surface of polystyrene/polyamine graft copolymers

Adhesion behavior of lymphnode lymphocytes on polystyrene/polyamine graft copolymer surfaces having microphase separated structures

PURPOSE: A lymphocyte suspension is brought into contact with a separating material made of a water-insoluble solid where amino groups unevenly distributes on its surface in a flow state to effect rapid and effective separation of B-cell from the suspension. CONSTITUTION: A column 3 is filled with a separating material 5 made of a water-insoluble solid where a hydrophobic compound and a compound having amino groups, represented by the formula [R is C l H 2l+1 (l=1W3); m is 1W3] unevenly distribute on the surface and equipped with a filter 4 on the outlet side 2. A lymphocyte suspension is fed from the inlet 1 and brought into contact with the separating material in a flow state to separate B-cell from the suspension. When animal serum protein is applied to the separating material, the adhesivity of lymphocytes is reduced as a whole to increase separation selectivity for T from B cell. COPYRIGHT: (C)1983,JPO&Japio

Tetsuo Watanabe

Papers

Differential retention of lymphocyte subpopulations (B and T cells) on the microphase separated surface of polystyrene/polyamine graft copolymers

Adhesion behavior of lymphnode lymphocytes on polystyrene/polyamine graft copolymer surfaces having microphase separated structures

B-cell separating material, separator and process therefor