Spinal cord injury (SCI), one of the most serious injuries of the central nervous system, causes physical functional dysfunction and even paralysis in millions of patients. As a matter of necessity, redressing the neuroleptic pathologic microenvironment to a neurotrophic microenvironment is essential in order to alleviate this dilemma and facilitate the recovery of the spinal cord. Herein, based on cell-sheet technology, two functional cell types�uninduced and neural-induced stem cells from human exfoliated deciduous teeth�were formed into a composite membrane that subsequently self-assembled to form a bioactive scaffold with a spinal-cord-like structure, called a spinal cord assembly (SCA). In a stable extracellular matrix microenvironment, SCA continuously released SCA-derived exosomes containing various neurotrophic factors, which effectively promoted neuronal regeneration, axonal extension, and angiogenesis and inhibited glial scar generation in a rat model of SCI. Neurotrophic exosomes significantly improved the pathological microenvironment and promoted in situ centralis neuroplasticity, ultimately eliciting a strong repair effect in this model. SCA therapy is a promising strategy for the effective treatment of SCI based on neurotrophic exosome delivery.

Introduction: After spinal cord injury (SCI) occurs, the lesion is in a growth inhibitory microenvironment that severely hinders neural regeneration. In this microenvironment, inhibitory factors are predominant and factors that promote nerve regeneration are few. Improving neurotrophic factors in the microenvironment is the key to treating SCI.Methods: Based on cell sheet technology, we designed a bioactive material with a spinal cord‐like structure –SHED sheet induced with homogenate protein of spinal cord (hp–SHED sheet). Hp–SHED sheet was implanted into the spinal cord lesion for treating SCI rats with SHED suspensions as a control to investigate the effects on nerve regeneration.Results: Hp–SHED sheet revealed a highly porous three–dimensional inner structure, which facilitates nerve cell attachment and migration. Hp-SHED sheet in vivo restored sensory and motor functions in SCI rats by promoting nerve regeneration, axonal remyelination, and inhibiting glial scarring.Discussion: Hp–SHED sheet maximally mimics the microenvironment of the natural spinal cord and facilitate cell survival and differentiation. Hp–SHED sheet could release more neurotrophins and the sustained action of neurotrophins improves the pathological microenvironment, which effectively promotes nerve regeneration, axonal extension, and inhibits glial scarring, thereby promoting the in situ centralis neuroplasticity. Hp–SHED sheet therapy is a promising strategy for effective treatment of SCI based on neurotrophins delivery.

Background: Global population growth and population aging continue to accelerate, and lead to a further increase in the risk of neurological diseases worldwide. Extracellular vesicles secreted by mesenchymal stem cells carry many proteins, lipids, and genetic material that mediate cell-to-cell communication and improve therapeutic outcomes for neurological disorders. Stem cells from human exfoliated deciduous teeth are considered a suitable cell source for tissue regeneration, which exerts therapeutic effects via the secretion of exosomes. Methods: This study was performed to assess the effect of functionalized exosomes on neural differentiation of embryonic carcinoma cell line P19. We stimulated stem cells from human exfoliated deciduous teeth with the glycogen synthase kinase-3β inhibitor TWS119 and then extracted its exosomes. P19 cells were induced to differentiate using functionalized exosomes, and the biological functions and involved signaling pathways of differentially expressed genes were analyzed by RNA-sequencing. Immunofluorescence techniques detected neuronal specific markers. Results: It was found that TWS119 activated the Wnt signaling pathway in stem cells from human exfoliated deciduous teeth. RNA-sequencing showed that upregulated differentially expressed genes in the functionalized exosome-treated group were responsible for cell differentiation, neurofilament, and structural constituent of the synapse. Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that the functionalized exosome-treated group activated the Wnt signaling pathway. Immunofluorescence showed that functionalized exosomes induced neurite outgrowth in P19 cells. Conclusion: Our results demonstrated that functionalized exosomes promoted neural differentiation of P19 cells by activating the Wnt signaling pathway.