AVS 57th International Symposium & Exhibition
    Biomaterial Interfaces Thursday Sessions
       Session BI1+NS-ThM

Paper BI1+NS-ThM5
Uniform Spheroid Formation Using a “Smart” Polymer

Thursday, October 21, 2010, 9:20 am, Room Taos

Session: Replicating Biological Environments and Processes
Presenter: J.A. Reed, University of New Mexico
Authors: J.A. Reed, University of New Mexico
J.P. Freyer, University of New Mexico
H.E. Canavan, University of New Mexico
Correspondent: Click to Email
Spheroids are small (~50-1000 µm diameter) sphere-shaped aggregates of cells that have been developed as 3D models for tumors. In addition to providing a model that more closely approximates the microenvironments of tissues and tumors than 2D cultures, spheroids can be more easily controlled than tests preformed on animal models. Current approaches for spheroid formation result in spheroids with a wide size distribution (>25% standard deviation), requiring the use of secondary sorting to obtain a uniformly-sized population. To increase the efficacy of these models for drug discovery in cancer therapeutics, it is necessary to develop an efficient way to fabricate a large number of uniform spheroids. Using a thermoresponsive polymer, poly(N-isopropyl acrylamide) (pNIPAM), cell aggregates of reproducible size and cell density can also be obtained. In this work, we pattern pNIPAM on an anti-fouling substrate to direct cell attachment, and ultimately cell sheet detachment for uniform spheroid formation. Using plasma polymerization, pNIPAM is patterned on Pluornic® F-127, which is nonfouling, to form 300µm diameter reversibly cell adhesive “islands” in non-fouling Pluornic® F-127 “seas.” EMT6 cells are grown to confluence on the islands in 2 days, at which time their growth media is exchanged to stimulate cell detachment to form 70 spheroids of ~100µm from each 35mm diameter substrate. To verify pattern fidelity, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), atomic force microscopy (AFM), and contact angle goniometry are used. In addition to developing a novel technique for the formation of tumor analogs, we also find that use of the larger surface area: volume ratio accelerates the speed of cell release.