PEG-based bioactive hydrogels crosslinked via phosphopantetheinyl transferase
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1272-PP07-04
PEG-based bioactive hydrogels crosslinked via phosphopantetheinyl transferase Katarzyna A. Mosiewicz1, Kai Johnsson2 and Matthias P. Lutolf1 1 Laboratory of Stem Cells Bioengineering, Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland 2 Laboratory of Protein Engineering, Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland ABSTRACT State-of-the-art tissue engineering strategies increasingly rely on the performance of bioactive hydrogels formed via cell-friendly crosslinking reactions. Enzymatic reactions possess ideal characteristics for such applications, but they are currently still underexplored in biomaterials design. Here we report the development of hybrid bioactive hydrogels formed via a posttranslational modification reaction using phosphopantetheinyl transferase (PPTase). PPTase was shown to catalyze the covalent crosslinking of CoenzymeA-functionalized poly(ethylene glycol) (PEG) multiarm macromers and recombinantly produced acyl carrier protein (ACP) dimers. Crosslinking kinetics and physicochemical properties of PPTase hydrogels were characterized. Proof-of-principle experiments demonstrate the successful covalent biofunctionalization of gels with a CoA-derivatized cell adhesion peptide. Polymerization of gels in the presence of primary mammalian cells was shown to result in no loss in cell viability compared to a well established, chemically crosslinked gel system.
INTRODUCTION The tissue-specific milieu that harbors cells in our tissues is critical for their function. A complex mixture of extracellular signaling cues delivered by neighboring cells and the extracellular matrix (ECM) regulates key cell functions including cell adhesion, migration, proliferation and differentiation. The rapid increase in the molecular understanding of the regulatory role of this cellECM crosstalk in recent years has opened the door for the design of novel families of ‘smart’ biomaterials, which allow recapitulating key functions of natural ECM to manipulate cell behavior in a well-controllable manner. Owing to their structural and physicochemical similarities to natural ECM, synthetic hydrogels have shown to be particularly promising candidates as scaffolds for cell biology and tissue engineering. An important criterion for the performance of synthetic hydrogels applied in biological contexts is a suitable chemical strategy to enable the self-selective gel cross-linking as well as the tethering of desired biomolecules to the gel under physiological conditions. Such crosslinking reactions allow forming gels in situ, that is, in the presence of biomolecules or cells present in tissues. Apart from a few selective covalent reactions including Michael-type addition reactions[1], click chemistry[2] or native chemical ligation[3], enzymatic reactions, which are specific by their very nature, are ideal targets to catalyze gel formation. Surprisingly, only relatively few enzymatic reactions including transglutaminases
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