Elastin-like polypeptides are artificial repetitive protein biopolymers derived from the hydrophobic domains of elastin. Like the latter, they exhibit interesting thermosensitive behavior in that they are completely soluble below a certain temperature, whereas they aggregate and undergo phase separation upon a temperature rise. The research activity has led to the creation of a prototype macromolecule called HELP (Human Elastin-like Polypeptide), whose sequence is based on the repeated hexapeptide motif and the cross-linking domains of human elastin. The team expertise ranges from molecular biology, biochemistry, applied biotechnology and new generation biomaterials. The scientific activity led to the realization of the HELP (Human Elastin-like Polypeptides) platform. Elastin-like polypeptides are artificial protein biopolymers based on the amino acid sequence of the hydrophobic elastin domains. Similarly to elastin, they present an interesting thermo-responsive behavior, being soluble below a threshold temperature and undergoing aggregation and phase separation after temperature rise. The research activity allowed the production of a prototypic macromolecule that was named HELP (Human Elastin-like Polypeptide). The sequence is based on the repeated hexapeptidic motif and on the crosslinking domain of the human elastin. Subsequently, an enzymatic method for the preparation of hydrogel-like matrices from HELP was developed, which led to the filing of a patent application. Recently, a new biopolymer, named UELP, based on the most conserved nonapeptidic motif of the mammalian elastin homologues was produced.

This branch of research is characterized by  the extremely innovative content, both in terms of approach, aimed at creating new macromolecules that do not exist in nature but are assembled in the laboratory, as well as in terms of potential, since it opens the door to new scenarios that need to be explored and have great potential for application. Being in the field of biotechnology, a cutting-edge and distinctly multidisciplinary sector, these studies benefit greatly from the contributions of several disciplines such as molecular biology, physics, engineering, biochemistry, etc., while offering opportunities for collaboration between partners that work in these fields.

Elastin-like polypeptides for diagnosis and controlled release of bioactive compounds

Recombinantly produced biomimetic proteins represent a promising alternative to synthetic polymers for biomedical and biotechnological applications. The opportunity to realize tailored biomaterials with finely tuned functionality represents a veery interesting feature of such system. The HELP platform is currently based on two elastin-like polypeptides carrier that are versatile recombinant fusion partners for bioactive domains. The opportunity to purify the resulting fusion proteins exploiting the thermo-responsive phase transition properties that characterize elastin represents a significant advantage, ensuring high purification degree as well as high yield. Up to now, in our lab, around twenty recombinant fusion constructs carrying different functional domains based on the HELP carrier are available. The carriers and their fusion counterpart as well as the derived matrices are susceptible to elastolytic degradation. This feature can be exploited to produce diagnostic devices to monitor conditions characterized by this specific proteolytic activity, like infection, inflammation linked to pathologic conditions. The creation of smart devices to release the bioactive domain at the level of the infection or inflammation site exploiting the elastolytic stimuli represents a promising application. This system can also be a tool to study how the increase of the the elastolytic activity due to infection or inflammation is correlated with the damage of the elastic tissue.

1) Development of HELP polypeptides and lo-conjugates. The polypeptide HELP has been conjugated to the epidermal growth factor (EGF) and to the RGD sequences that promote cell adhesion. However, it can also be conjugated to other proteins that play a key role in binding to membrane receptors and activating intracellular signaling pathways required for growth and differentiation. These polypeptides are the basic compounds to obtain multifunctional composite materials suitable for the development of in vitro micro-physiological systems.

2) Components with antimicrobial capacity that prevent antibiotic resistance. HELP Polypeptides are still underexploited fusion partners to produce antimicrobial peptides. These latter are currently considered promising biodrugs that can replace conventional antibiotics. In the European Union-funded projects AIMED and STOP, the HELP platform is used to produce fusion proteins with antibiotic domains derived from human b-defensins. They will be used to produce biocompatible materials and surfaces that cannot be colonized by bacteria and do not induce resistance.