Reproducing the main physicochemical properties of tropoelastin by synthetic peptides is well described in the literature and many tropoelastin-inspired polypeptides have been developed so far. While their applications have been focused mainly on manufacturing elastino-mimetic biomaterials and have contributed to important innovations in the field of tissue engineering, little is known on how organisms would be able to recognize and integrate this kind of synthetic compounds to self-repair. Therefore, our working hypothesis is that our synthetic elastic protein, and whose preliminary results demonstrate that it is capable of effectively mimicking the mechanical and biological properties of human tropoelastin, could serve as an elastic molecular prosthesis in tissues. to compensate or restore the lack of elasticity.
To do this, the synthetic elastic protein (SEP) must meet five requirements, each corresponding to a specific objective of the project:
1- Delivering the right signal to cells with no deleterious effect
- This implies that SEP must be recognized by cells, particularly SMCs, as an integral protein and not as a peptide resulting from the degradation of elastin. This condition is the first step in allowing it to be captured in neosynthetized elastic fibre to strengthen the damaged network, while limiting pro-inflammatory signalling in vitro and in vivo.
- Inflammation signalling may also come from endotoxins resulting from the synthesis process of the SEP, indeed particular attention must be paid to the purification of this recombinant protein in endotoxin-free conditions.
2- Reaching the right location through the endothelial barrier
- To reach the arterial wall, and more precisely the media where the elastic lamellae are histologically located, the most obvious route of administration of the SEP is undoubtedly the intravenous injection. In the bloodstream, SEP should be captured by the endothelium and pass through the endothelial barrier. Although this is a common phenomenon for endogenous proteins and molecules, it remains a challenge for an exogenous biological compound.
- The SEP should also be retained in the blood stream without being cleared too quickly by the kidneys or detoxifying organs so that significant amounts of material reach their target. It will therefore also be necessary to determine the concentration and the frequency of injections making it possible to achieve effective results.
3- Being integrated into elastic fibres within vascular walls
- Due to the particular structure of the elastic fibres, the SEP must be able on the one hand to be crosslinked with the elastin polymer at the core of the fibres; and on the other hand to interact with the fibrillin-rich microfibrillary component to ensure a good overall behaviour.
- The fine characterization of in situ elastic fibre structure requires to be carried out at the ultra-structural level by transmission electron microscopy.
4- Improving arterial wall elasticity and/or physiological parameters in relevant animal models
- This item reveals the effectiveness of the treatment. This requires the use of adapted animal models recapitulating some of the symptoms observable in humans and representative of the three classifications of elastic fibre defect-related arterial diseases (ageing, genetics and non-genetic diseases).
- Efficiency refers to an improvement at several scales: physiological (blood pressure), pharmacological (induced-vasomotion) and mechanical. Pluridisciplinary means of monitoring in vivo and ex vivo must therefore be put in place.
- The arterial mechanical context at the time of incorporation of the SEP may also be decisive. For instance, the need for a prior relaxation of the fibres so that the SEP is extended to an intermediate state at equilibrium. In order to predict the mechanical state of the system, it is necessary to develop a numerical model taking into account the characteristics of the arterial wall and the SEP to define and possibly redesign the processing conditions and the properties of the SEP.
5- Manufacturing a synthetic protein with pharmaceutical grade requirements
- Another challenge will be to provide an innovative therapeutic medicine. This implies that a specific formulation of the synthetic protein must be addressed through the highly normative and rigorous quality controls of pharmaceutical compounds.
- The production stage will be outsourced to a competent company to obtain a GMP certified product to be further formulated as injectable doses at FRI Pharm. This deliverable is an important objective to allow for further preclinical and clinical applications.