Smart Scaffolds for Triggered Release of Bioactive Molecules during 3D Stem Cell Culture

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NESCI would be interested in funding / studentship opportunities for the following proposal.

NESCI are interested in industrial partners who may like to collaborate in one of these fields (for a CASE studentship or other awards), or in anyone who is interested in these areas of research (including other academic groups). For further details, please contact Helen Clamp from NESCI.

Project: Smart Scaffolds for Triggered Release of Bioactive Molecules during 3D Stem Cell Culture

Lead: Dr Stefan A. Przyborski and Prof. Neil R. Cameron

The in vitro culture of differentiated cells in three dimensions (3D) is used increasingly to provide cell cultures that are more representative of an in vivo environment, leading to better tissue and disease models. The investigators have developed a robust 3D cell culture platform, consisting of highly porous emulsion templated polystyrene-based materials, that has been shown to produce highly functional 3D cultures of a wide variety of cell types (including hepatocytic, osteoblastic, neuronal and mesenchymal stem cells) [Bokhari et al., 2007a; Bokhari et al., 2007b; Bokhari et al., 2007c; Carnachan et al., 2006; Hayman et al., 2005; Hayman et al., 2004]. To date, such scaffolds have consisted of unfunctionalised polymers and have provided a controlled physical, rather than chemical, environment for cell growth. In this project, we will extend this work to the development of surface-functionalised scaffolds that, ultimately, will be able to release bioactive molecules, in a triggered fashion, to control stem cell differentiation and/or fate.

The investigators have recently developed plasmachemical treatment methodology that introduces reactive sites onto the surface of the scaffolds. These can be used to anchor bioactive molecules for subsequent release during 3D culture. Molecules of particular interest are the retinoid derivatives developed by Przyborski and colleagues, which cause efficient and controlled differentiation of human pluripotent stem cells [Christie et al., 2008]. These will be attached to functionalised scaffolds via degradable linkers, such as thioesters, causing their release into the medium during culture. A second generation of scaffolds will be designed to release retinoids in response to the application of (low intensity) light, by means of a photocleavable linker (e.g. an o-nitrophenyl ester). Thus, the retinoid, or other bioactive factor, can be released into the medium at selected timepoints during the culture experiment. Combinations of both types of linker will allow the release of mixtures of factors, one at a constant and slow rate during the experiment and the other in a burst, on application of light. The effect of not only the bioactive species, but also the point at which it is released, on stem cell differentiation can be investigated in this manner, as well as the interplay between different factors.

References
M. Bokhari, R.J. Carnachan, S.A. Przyborski, N.R. Cameron, J. Mater. Chem., 17, 4088-4094 (2007).
M. Bokhari, R.J. Carnachan, N.R. Cameron, S.A. Przyborski, J. Anatomy, 211, 567-576 (2007).
M. Bokhari, R.J. Carnachan, N.R. Cameron, S.A. Przyborski, Biochem. Biophys. Res. Commun., 354, 1095-1100 (2007).
R.J. Carnachan, M. Bokhari, S.A. Przyborski, N.R. Cameron, Soft Matter, 2, 608-616 (2006)
M.W. Hayman, K.H. Smith, N.R. Cameron, S.A. Przyborski, Biochem. Biophys. Res. Commun., 314, 483-488 (2004).
M.W. Hayman, K.H. Smith, N.R. Cameron, S.A. Przyborski, J. Biophys. Biochem. Methods, 62, 231-240 (2005).