posted on 2022-01-04, 19:33authored byMichelle
D. Drewry, Matthew T. Dailey, Kristi Rothermund, Charles Backman, Kris N. Dahl, Fatima N. Syed-Picard
Current treatments
of facial nerve injury result in poor functional
outcomes due to slow and inefficient axon regeneration and aberrant
reinnervation. To address these clinical challenges, bioactive scaffold-free
cell sheets were engineered using neurotrophic dental pulp stem/progenitor
cells (DPCs) and their aligned extracellular matrix (ECM). DPCs endogenously
supply high levels of neurotrophic factors (NTFs), growth factors
capable of stimulating axonal regeneration, and an aligned ECM provides
guidance cues to direct axon extension. Human DPCs were grown on a
substrate comprising parallel microgrooves, inducing the cells to
align and deposit a linearly aligned, collagenous ECM. The resulting
cell sheets were robust and could be easily removed from the underlying
substrate. DPC sheets produced NTFs at levels previously shown capable
of promoting axon regeneration, and, moreover, inducing DPC alignment
increased the expression of select NTFs relative to unaligned controls.
Furthermore, the aligned DPC sheets were able to stimulate functional
neuritogenic effects in neuron-like cells in vitro. Neuronally differentiated neuroblastoma SH-SY5Y cells produced
neurites that were significantly more oriented and less branched when
cultured on aligned cell sheets relative to unaligned sheets. These
data demonstrate that the linearly aligned DPC sheets can biomechanically
support axon regeneration and improve axonal guidance which, when
applied to a facial nerve injury, will result in more accurate reinnervation.
The aligned DPC sheets generated here could be used in combination
with commercially available nerve conduits to enhance their bioactivity
or be formed into stand-alone scaffold-free nerve conduits capable
of facilitating improved facial nerve recovery.