Effects of human embryonic stem cell-derived Schwann cells for nerve regeneration after facial nerve injury.

Abstract

Facial nerve transection frequently results in incomplete functional recovery despite microsurgical repair due to axonal misalignment and limited intrinsic regenerative capacity. Schwann cells (SCs) are essential for peripheral nerve repair, supporting axon elongation, remyelination, and neurotrophic signaling. Human embryonic stem cell-derived Schwann cells (hESC-SCs), including Schwann cell precursors (SCPs) and immature SCs, constitute a scalable source of cells for tissue-engineered nerve grafts. This study investigated whether silicone conduits loaded with hESC-SCs could enhance facial nerve regeneration following complete transection in rats. hESCs were differentiated into SCPs or immature SCs using a stepwise in vitro protocol and purified by fluorescence-activated cell sorting (FACS). Forty-eight Sprague-Dawley rats underwent right facial nerve transection with a 3-mm gap and were randomly assigned to six groups: sham, axotomy only, empty conduit, Matrigel-filled conduit, conduit with SCPs, or conduit with immature SCs. At 12 weeks post-surgery, toluidine blue histochemistry, transmission electron microscopy (TEM), and morphometric evaluation demonstrated significantly larger axonal diameters, thicker myelin sheaths, and improved g-ratios in SC-treated conduits compared with empty conduit and axotomy-only controls (P < 0.05). Behavioral assessments showed partial functional recovery in SC-treated groups, with blink reflex performance significantly superior to controls at 8 and 12 weeks (P < 0.05). No significant differences were found between SCP and immature SC groups. These findings suggest that hESC-SCs incorporated into bioengineered conduits represent a potentially effective cell-based strategy for peripheral nerve regeneration. However, the interpretation of mechanistic effects is limited by the absence of direct engraftment validation and molecular analyses.