Bioactive Polymeric Scaffolds and Nanoformulates in Pain Management and Nervous System Tissue Engineering

The research carried out within this PhD project was focused on three main topics: the pain management, the nervous system tissue engineering and the polymer genomics, sharing as common feature the study and application of polymeric biomaterials. The first objective was to improve the quality of pain control, developing an implantable polymer-based biodegradable drug delivery system able to sustain viable and metabolically active PC-12 cell line in the view of controlled release of natural “endogenous” opioids. Because of the rapid expanding knowledge of new bioactive polymers obtained from low cost source such as polysaccharides, alginate, as reference material, and ulvan, a new alginic material derived from green algae (Ulva Armoricana), were selected. Alginate/ulvan based scaffolds, films or micro-beads were prepared using both plain polymers and functionalized ones, and different cross linking methods either physical or chemical (enzymatic and UV induced) were used. Spectroscopic, morphological and in vitro biological characterizations were carried out. Furthermore, a preliminary investigation was focused on the set up of a method for the extraction of morphine from PC-12 pellet and its quantitative evaluation by HPLC. Functional polysaccharide materials (alginate and ulvan) displayed good cytocompatibility properties and a very high versatility in processing, showing a good suitability to be functionalized and to be susceptible to different cross linking methods. The procedure of morphine identification from PC-12 cell line demonstrated a possible inefficiency of the extraction method. The aim of the second objective was to study the suitability of different synthetic polymeric scaffolds for neural tissue engineering, using as a model SK-N-SH human neuroblastoma cell line. Evidences of cell proliferation and adhesion on poly(lactic-co-glycolic acid) based films and agmatine (5-10%)-containing poly amidoamine hydrogels. were confirmed by mean of colorimetric assays and confocal microscopy analysis. In addition, the in vitro evaluation of the ability of all-trans-retinoic acid (ATRA) loaded nanoparticles to induce SK-N-SH neural differentiation was also investigated. Cells were exposed to 2-methoxyethanol hemiester of poly(maleic anhydride-alt-butyl vinyl ether) based nanoparticles loaded with ATRA and the results showed that the activity of the bioactive principle was not impaired by incorporation and purification processes, inducing phenotypic differentiation. Moreover, the third objective concerned the investigation of the changes of intracellular mechanisms in a breast cancer multidrug resistant cell line (MCF-7/ADR), after exposure to block copolymer Pluronic P85. The depletion in ATP levels in Na-K ATPase pump present into cells plasma membrane was confirmed after P85 exposure. Simultaneously, intracellular ions (sodium, potassium and calcium) showed unclear dynamics after pluronic exposure.