(123a) Surface Modified Electrospun Fibers for Investigating the Relative Influence of Chemical and Topographical Cues On Tumor Cell Migration

Tumor cells are known to respond to the extracellular matrix (ECM) environment by altering their morphology and migration rate. However, there are few in vitro models that permit investigation of the relative effects of chemistry vs. topographical/mechanical cues in this process. Here, we present brain mimetic materials consisting of surface modified electrospun fibers (EFs) that maintain similar mechanical and topographical features, while displaying differing surface chemical functionalization.

As a model tumor system, we are investigating glioblastoma multiforme (GBM), a disease afflicting more than 22,500 individuals in the United States annually. These cancers are characterized by their infiltrative capacity and high degree of mobility; median patient survival is extremely low (~12-15 months) [1]. Clinical observations suggest that migration often occurs as single cells along white matter tracks, glial limitans externa and blood vessel periphery [2]. Aligned poly (ε-caprolactone) (PCL) electrospun fibers (EFs), in vitro biomaterials used in our study, closely mimic in vivo topographical features (i.e., blood vessels and white matter) and have diameters of ~ 700 nm, similar to physiological values ranging from 500 nm to 3 µm corresponding to fiber densities of ~10,000-30,000/mm² [3]. To further recapitulate in vivo environments in our in vitro models, we have modified PCL EFs with collagen-I (Col-I), collagen-IV (Col-IV), Hyaluronic acid (HA), and myelin basic protein (MBP)), representative of the blood vessel ECM, native brain ECM, and white matter ECM, respectively [4]. In addition, we have also created a model of white matter consisting of fibers myelinated by oligodendrocyte cells (myelinating cells of the central nervous system).

Aligned nanofiber multi-well plates were obtained from NanoFiber Solutions (Columbus, OH). Protein solutions of Col-I, IV and MBP (100 µg/mL) and HA (5 mg/ mL) were deposited on aligned fibers by simple adsorption. The presence of proteins on aligned fibers was quantified using immunofluorescence and that of HA confirmed using FITC-labeled HA. To complement protein adsorption, we also investigated EDC-mediated chemical conjugation techniques and quantified protein presence using micro-BCA assays. We are currently investigating GBM migration rates on surface modified aligned fibers using both techniques and examining specific chemistries that promote/hinder migration. In addition to protein modification of aligned fibers, we are also culturing oligodendrocytes on aligned fibers to create myelinated EFs as white matter mimetics. We have shown that oligodendrocytes align to PCL EFs and display myelination behaviors, including production of myelin basic protein (MBP). Myelinated fibers display remarkable similarities to native white matter. Ultimately, by using these biomimetic substrates, we hope to gain a better fundamental understanding of GBM migration mechanisms, eventually leading to discovery of better therapeutics.

References:

[1] P.Y. Wen et al., N Engl J Med. 2008. 359 (5); 492-507.

[2] A.C. Bellail et al., Int J Biochem Cell Biol. 2004. 36 (6); 1046-1069.

[3] M.K. Makino et al., Spine. 1996. 21(9): p. 1010-1016.

[4] A Giese and M Westphal., Neurosurgery. 1996;39(2):235-50; discussion 50-2.