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A heparin-mimicking polymer conjugate stabilizes basic fibroblast growth factor

Nature Chemistry volume 5, pages 221–227 (2013)Cite this article

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Abstract

Basic fibroblast growth factor (bFGF) is a protein that plays a crucial role in diverse cellular functions, from wound healing to bone regeneration. However, a major obstacle to the widespread application of bFGF is its inherent instability during storage and delivery. Here, we describe the stabilization of bFGF by covalent conjugation with a heparin-mimicking polymer, a copolymer consisting of styrene sulfonate units and methyl methacrylate units bearing poly(ethylene glycol) side chains. The bFGF conjugate of this polymer retained bioactivity after synthesis and was stable to a variety of environmentally and therapeutically relevant stressors—such as heat, mild and harsh acidic conditions, storage and proteolytic degradation—unlike native bFGF. Following the application of stress, the conjugate was also significantly more active than the control conjugate system in which the styrene sulfonate units were omitted from the polymer structure. This research has important implications for the clinical use of bFGF and for the stabilization of heparin-binding growth factors in general.

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Figure 1: Syntheses and cytotoxicity study of the polymers.
Figure 2: Conjugation of the polymers to bFGF and characterization.
Figure 3: Stability study of bFGF–heparin-mimicking polymer conjugate bFGF–p(SS-co-PEGMA), compared to control groups.
Figure 4: Inhibition of FGFR1 activation induced by bFGF and the bFGF–heparin-mimicking polymer conjugate bFGF–p(SS-co-PEGMA).
Figure 5: Proliferation study with BaF3 cells in response to the addition of the heparin-mimicking polymer and its bFGF conjugate.

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Acknowledgements

This work was supported by the National Science Foundation (CHE-0809832) and the National Institutes of Health (R01 EB136774 to H.D.M.; R01 GM103479 to J.A.L.). The authors thank D. Ornitz (Washington University) for providing the engineered BaF3 cell line.

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Authors and Affiliations

  1. Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, 90095, California, USA

    Thi H. Nguyen, Sung-Hye Kim, Caitlin G. Decker, Darice Y. Wong, Joseph A. Loo & Heather D. Maynard

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  1. Thi H. Nguyen
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Contributions

T.H.N. prepared the polymers and the conjugates, performed the biological cell studies and the mass spectrometry measurements, devised some of the experiments, and prepared the manuscript. S.H.K. initiated the on-column conjugation technique and initiated cell experiments. C.G.D. helped with the polymer syntheses. D.Y.W. assisted with the cell studies and performed statistical analyses. J.A.L. advised on the mass spectrometry and ion mobility studies. H.D.M. devised the project and many of the experiments, supervised all experiments, and helped analyse the data. All authors assisted with editing the manuscript.

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Correspondence to Heather D. Maynard.

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Nguyen, T., Kim, SH., Decker, C. et al. A heparin-mimicking polymer conjugate stabilizes basic fibroblast growth factor. Nature Chem 5, 221–227 (2013). https://doi.org/10.1038/nchem.1573

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