Biomimetic proteosaccharide 3d scaffold for applications in tissue engineering

Abstract

Traumatic brain injuries (TBI) are considered a leading cause of morbidity and mortality all over the world particularly in adolescents and the elderly. TBI are just the beginning of long term, secondary complications such as inflammation, neurological impairment and neureodegeneration. The lack of successful pharmacological interventions to prevent the psychological, social, and physical aspects. Treatments to date are mainly symptomatic and focus on alleviating intracranial hypertension and convulsions. Tissue engineering aims to engender scaffolds which mimic the extracellular matrix (ECM) environment on a micro-, macro- and nano scale. Some tissue- engineered scaffolds show some experimental success, however, there remains the need for a thee-dimensional scaffold that exhibits consummate results of a clinical standard. To this end, research was conducted on protein-polysaccharide conjugates which could play a great role in neural regeneration.

This research employed two different proteosaccharide combinations, namely chitosan-gelatin and hyaluronic acid-gelatin, of which both were chemically crosslinked by the non-toxic crosslinker genipin. Various parameters, such as the temperature of crosslinking and time needed for crosslinking were troubleshooted, and two thee-dimensional scaffolds were synthesised, one being a full-IPN (Interpenetrating Polymeric Network) and the second, being a semi-IPN. Various characterization studies were employed, including Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Rheology, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), drug release and degradation studies. In vitro cytotoxicity assays were also carried out using of rat pheochomocytoma (PC12) and human glioblastoma multiform (A172). The polysaccharides increased the mechanical strength of each scaffold while gelatin provided the bioactive sequence which promoted cellular interactions. The effect of crosslinking was investigated, and the crosslinked hydrogels showed higher thermal decomposition temperatures, increased resistance to degradation, and pore sizes ranging from 72.789 um+16.85 for the full IPN and 84.289 um+7.658 for the semi IPN. The scaffolds were loaded with Dexamethasone-21-phosphate to investigate their efficacy as drug delivery vehicles, and the full IPN showed a 100% release in 10 days, while the semi-IPN showed a burst release in 6 hours. Both scaffolds encouraged the proliferation of rat pheochomocytoma (PC12) and human glioblastoma multiform (A172) and furthermore, provided cues for migration of A172 cells. Both scaffolds can be used as potential drug delivery vehicles and as artificial extracellular matrices for potential neural regeneration.