Olfactory Bulb-Derived Cells Seeded on 3D Scaffolds Exhibit Neurotrophic Factor Expression and Pro-Angiogenic Properties

Abstract

Olfactory bulb (OB)-derived cells include fibroblasts, astrocytes, and olfactory ensheathing cells (OECs). OECs are a distinctive type of glia that secrete neurotrophic factors and form myelin sheaths around axons projecting from the olfactory mucosa into the OB of the central nervous system. Their unique properties make them candidates for cell therapy of spinal cord injury (SCI). Current SCI cellular repair techniques suffer from massive cell loss post implantation. To overcome this difficulty, we propose to seed and propagate OB-derived cells on biodegradable scaffolds to form a stable tissue construct. Upon implantation, scaffolds may serve as carriers to introduce the tissue into the lesion site. In this study, we characterized OB-derived cells cultured on biodegradable poly-l-lactic acid/polylactic-co-glycolic acid scaffolds in vitro. We showed that cells remained viable and proliferative for up to 2 weeks on the scaffolds. We have shown that OB-derived cells induce neuronal differentiation of pheochromocytoma cells (PC12) on scaffolds, and that a purified population of OECs is sufficient for the differentiation. Selective inhibition of nerve growth factor (NGF) on PC12 cells blocks the differentiation. We have shown that the expression of BDNF and NGF genes in OB-derived cells grown on 3D scaffolds compared to 2D monolayer cultures was significantly upregulated. In addition, OB-derived cells stimulated network formation of endothelial cells grown on the same scaffolds. Taken together, these results clearly demonstrate the vast potential of 3D scaffolds in maintaining and strengthening the unique therapeutic properties of embedded OB-derived cells. This strategy will enable more efficient therapeutic usage of OB-derived cells for treatment of SCI.