Single Odontoblast Polarization in a Bio-inspired 3D Platform

Objectives: An odontoblast is a highly polarized cell with a long process that extends deeply into a dentinal tubule. The polarization of odontoblasts is a prerequisite for the formation of tubular dentin that is crucial for maintaining the normal biological functions of a tooth. It is well accepted that the odontoblast polarization is initiated and modulated by a variety of biophysical and biochemical signals. Because those factors are interweaved to form a complex signaling network, it is very difficult, if not impossible, to decipher them in vivo. Therefore, the mechanism of odontoblast polarization remains largely ambiguous. In this work, we report the development of a unique bio-inspired three-dimensional (3D) in vitro platform that controls single odontoblast polarization and is capable of dissecting the signals that initiate and regulate odontoblast polarization.
Methods: An extracellular matrix (ECM)-like nanofibrous micropatterned 3D matrix was developed using an approach that combined electrospinning, chemical crosslinking, and a polyethylene glycol (PEG)-based photolithography process. A laser-guided ablation process was further applied to introduce tubular microstructure into the nanofibrous micropatterned matrix to form a bio-inspired 3D platform. By choosing the size of the microisland, the 3D platform accommodated only one human dental pulp stem cell (DPSC) on each microisland of the platform. The cell morphology, cell adhesion, and cellular process components were observed using confocal microscopy. The polarization of the DPSC that includes the formation of cellular process and the movement of Golgi apparatus were recorded at selected time points.
Results: The bio-inspired 3D platform successfully initiated single DPSC to polarize in vitro. The 3D tubular architecture was identified to be a crucial biophysical factor to initiate DPSC polarization. The polarized DPSC exhibited a functional long process of more than 20 um within the 3D platform, and the Golgi apparatus of the DPSC moved to a position that is similar to a polarized odontoblast in vivo.
Conclusions: We developed an excellent 3D platform for studying odontoblast polarization in vitro.