Control of Neural Stem Cell Survival by Electroactive Polymer Substrates
Citation: Lundin V, Herland A, Berggren M, Jager EWH, Teixeira AI (
Control of Neural Stem Cell Survival by Electroactive Polymer Substrates
Vanessa Lundin 0
Anna Herland 0
Magnus Berggren 0
Edwin W. H. Jager 0
Ana I. Teixeira 0
Meni Wanunu, University of Pennsylvania, United States of America
0 1 Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden , 2 Organic Electronics , Department of Science and Technology, Linko ping University , Norrk o ping , Sweden
Stem cell function is regulated by intrinsic as well as microenvironmental factors, including chemical and mechanical signals. Conducting polymer-based cell culture substrates provide a powerful tool to control both chemical and physical stimuli sensed by stem cells. Here we show that polypyrrole (PPy), a commonly used conducting polymer, can be tailored to modulate survival and maintenance of rat fetal neural stem cells (NSCs). NSCs cultured on PPy substrates containing different counter ions, dodecylbenzenesulfonate (DBS), tosylate (TsO), perchlorate (ClO4) and chloride (Cl), showed a distinct correlation between PPy counter ion and cell viability. Specifically, NSC viability was high on PPy(DBS) but low on PPy containing TsO, ClO4 and Cl. On PPy(DBS), NSC proliferation and differentiation was comparable to standard NSC culture on tissue culture polystyrene. Electrical reduction of PPy(DBS) created a switch for neural stem cell viability, with widespread cell death upon polymer reduction. Coating the PPy(DBS) films with a gel layer composed of a basement membrane matrix efficiently prevented loss of cell viability upon polymer reduction. Here we have defined conditions for the biocompatibility of PPy substrates with NSC culture, critical for the development of devices based on conducting polymers interfacing with NSCs.
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Funding: The authors would like to acknowledge funding from the Swedish Research Council (VR) and the Swedish Foundation for Strategic Research (SSF; the
OBOE center). V.L. was supported by a KID fellowship from the Karolinska Institute and A.H. was supported by a post-doctoral grant from VR. M.B. wishes to thank
the O nnesjo Foundation and Linko ping University for financial support. The funders had no role in study design, data collection and analysis, decision to publish,
or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
. These authors contributed equally to this work.
The stem cell microenvironment holds the balance between
stem cell proliferation and differentiation, critical during
embryonic development and tissue regeneration. Microenvironmental
cues include chemical signals originating from the extracellular
matrix, soluble growth factors and cell-cell interactions. In
addition, we and others have previously shown that the physical
nature of the microenvironment provides mechanical [1,2] and
topographical [3,4] cues to cells. Conducting polymer-based
devices have the potential to afford a high degree of control over
the physical and chemical stimuli sensed by stem cells and thereby
provide new insights into the mechanisms that regulate stem cell
state and fate [5,6]. Additionally, manipulating the stem cell
microenvironment in vivo through conducting polymer scaffolds
holds promise to improve the outcomes of stem cell therapy.
Neural stem cells are self-renewing, multipotent cells present in
the developing and adult central nervous system (CNS) that have
the ability to differentiate into all neural lineages. Neural stem cells
isolated from developing embryos at embryonic day 15.5 (fetal
NSCs) have proven valuable for understanding CNS development
and neurodevelopmental disorders [7]. Further, neural stem cells
derived from pluripotent embryonic stem cells (ESC-NSCs)
constitute a readily available progenitor population that has the
potential to be instrumental in cell therapy in the CNS [8].
However, the development of methods to control the NSC
microenvironment in vitro and in vivo is required to realize the
promise of NSCs as a tool for understanding embryonic
development and for cell therapy.
Reversible switching between redox states of conducting
polymers can dynamically control bulk properties such as volume,
conductivity and mechanical properties [9]. Additionally, the
surface tension and surface chemistry of conducting polymers can
be tailored by the synthesis method and the redox state of the
polymers [10,11]. The counter ion incorporated upon synthesis of
conducting polymers has critical significance for their physical and
chemical properties and their biocompatibility [12].
We investigated the biocompatibility of neural stem cells of fetal
and embryonic origin with polypyrrole (PPy) substrates containing
four anionic dopants of varying molecular weight and chemical
character: dodecylbenzenesulfonate (DBS), tosylate (TsO),
perchlorate (ClO4) and chloride (Cl). These dopants were selected due
to previous extensive (...truncated)