Aligned Schwann cells derived from human dental pulp stem cells direct neurite growth in a tissue engineered collagen construct

Abstract

A variety of traumas and diseases can cause peripheral nerve injury (PNI). In the process of spontaneous healing, Schwann cells (SC) are very important players. They not only reconstitute myelin, essential for proper nerve function, but also organize themselves into columns that lie within the endoneurial tubes to guide and support axonal regeneration from the proximal to the distal end of the injury. By contrast, large gap PNI requires artificial bridging strategies such as highly aligned scaffolds to promote directed neurite outgrowth. In the field of neural tissue engineering, hydrogels are very attractive biomaterials to encapsulate cells. Their high water content facilitates transport of oxygen, nutrients and waste and their viscoelastic properties can be relatively easy modulated. Recently, a new technique has been developed to efficiently and reproducibly align cells in a collagen type I hydrogel, thereby mimicking the environment required for nerve regeneration. This Engineered Neural Tissue (ENT) has given promising preliminary results with immortalized and primary rat SC both in vitro and in vivo. However, the use of human cells would be a significant advance in bringing this ENT from bench to bedside. Since autologous SC must be harvested from another peripheral nerve and are slowly growing in vitro, there is a high need for alternative cell types such as human dental pulp stem cells (hDPSC). hDPSC can be easily isolated from discarded teeth with very little ethical issues and their neural crest origin suggests a predisposition to differentiate into neural or glial cells. Preliminary experiments in our laboratory indicate the two-dimensional (2D) in vitro transdifferentiation capacity of human DPSC (hPDSC) into Schwann-like cells (SC-hDPSC). Here, we evaluate the potential of SC-hDPSC to align within a collagen type I hydrogel and determine the effects of this ENT on dorsal root ganglion neuron neurite outgrowth in vitro