Seite - (000249) - in Biomedical Chemistry: Current Trends and Developments

release of matrix-associated growth factors and morphogens to enhance tissue regeneration (Lin & Anseth, 2009; Chan & Mooney, 2008). Most ECM proteins, including collagen, fibrin, fibronectin, and laminin have specific cleavage sites for degradation by enzymes, such as matrix metalloproteinases (MMPs), plasmin, and elastase. In this perspective, MMPs and plasmin are particularly interesting as they participate in ECM remodelling and degradation, having a key role in wound healing and tissue regeneration. In particular, plasmin can degrade and remodel the provisional fibrin matrix act generated at the onset of clot formation and can also activate latent growth factors or morphogens by specific cleavage events (Page-Mc Caw, 2007; Patterson & Hubbell, 2011; Aizawa, 2012; Fonseca, 2013). The cleavage site specificity of proteolytic enzymes can be determined by means of combinatorial libraries which provide information applicable to the design of inhibitors and to the identification of protein substrates (Turk, 2001; Chau, 2004). The development of efficient drug delivery systems with enhanced therapeutic efficiency is relevant in cases where a prolonged treatment is required. Biodegradable enzyme-sensitive hybrid polymers are susceptible to the action of specific proteases yielding small nontoxic metabolites that can be easily excreted through natural body mechanisms. Their biocompatibility and low immunogenicity make them suitable for repeated parenteral administration and allow the use of high molecular weight carriers to optimise pharmacokinetics and high polymer doses (Duro-Castano, 2014). 3.1.3.3.4 Self-assembling Peptides as Biomaterials Biocompatible and bioactive small molecules, capable of self-assembly and degradation into predictable metabolites over time are ideal building blocks for scaffolds to regenerate tissues and organs. The high signaling capacity and therapeutic efficacy of peptide-based scaffolds is expected to open up the potential of self-assembling peptides as new therapeutic agents in regenerative medicine. Furthermore, these hydrogels are biocompatible since they are composed of simple naturally-occurring amino acids. There are several classes of self- assembling peptide-based materials, such as peptide amphiphiles,