PHBV Microspheres as Tissue Engineering Scaffold for Neurons

Polymeric microspheres are versatile tissue engineering scaffold, suitable for simultaneous drug delivery and surface modification. They are small units that can be individually tailored for different cell types and purposes, then assembled with various compositions and shapes. In addition, they provide a 3D environment for cell-cell and cell-material interactions. Poly(3-hydroxyburate-co-3-hydroxyvalerate) (PHBV, 8% PHV content), a biodegradable and biocompatible microbial polyester, was used to fabricate microspheres using an oil-in-water emulsion solvent evaporation technique. As PHBV is biodegradable, the eventual construct will consist of only natural tissues, avoiding chronic complications. The versatility of microspheres is useful in neural therapies which require several cell types and various biomolecular signals to overcome inflammation, glial scarring, and inhibitory signals, as well as to promote repair and regeneration. Due to cell source limitations, neuronal expansion might have to be carried out on the microspheres to yield enough neurons for therapies. Also, a key requirement for engineered neural tissue would be its functional integration into host tissue. Thus, the suitability of PHBV microspheres as neural tissue engineering scaffolds was investigated using neuro2a neuroblastoma cells as a model for proliferating neurons and primary mouse fetal cortical neurons as a model for functioning neurons. Scanning electron microscope (SEM) imaging, and confocal laser scanning microscopy were used to observe morphologies of cells cultured on PHBV microspheres. Also, DNA Quantification and cell viability assay (MTT assay) were carried out. Neuro2a cultures on PHBV microspheres showed a growth trend comparable to that in 2D culture plate controls, in both assays. Also, through immunoflourescence staining for beta-III tubulin, primary neurons were found to extend neurites on PHBV microspheres. The results showed that PHBV microspheres are suitable scaffolds for neural tissue engineering, as they support the neural cells' adhesion, growth, proliferation and differentiation.