Intranasal Administration of Umbilical Cord Mesenchymal Stem Cell Exosomes Alleviates Parkinson's Disease.

Parkinson's disease (PD) is a common and complex neurodegenerative disease. This disease is typically characterized by the formation of Lewy bodies in multiple brain regions and dopaminergic neuronal loss in the substantia nigra pars compacta, resulting in non-motor symptoms (e.g., olfactory deficits) and motor dysfunction in the late stages. There is yet no effective cure for Parkinson's disease. Considering the neuroprotective effects of exosomes, we investigated whether intranasal administration of umbilical cord mesenchymal stem cell exosomes could improve behavioral functions in PD mice. First, exosomes were endocytosed by the cells in vitro and in vivo, indicating that exosomes can cross the blood-brain barrier. Second, we found that both motor and non-motor functions of the PD models were effectively improved during intranasal exosomes treatment. Finally, the activity of olfactory bulb neurons was improved and the loss of dopaminergic neurons in the substantia nigra pars compacta was reversed. Moreover, exosomes attenuated microglia and astrocyte activation, leading to a low level of inflammation in the brain. In conclusion, our study provided a new reference for the clinical application of exosomes in the treatment of PD.

Spatiotemporal Dynamics of the Molecular Expression Pattern and Intercellular Interactions in the Glial Scar Response to Spinal Cord Injury.

Nerve regeneration in adult mammalian spinal cord is poor because of the lack of intrinsic regeneration of neurons and extrinsic factors - the glial scar is triggered by injury and inhibits or promotes regeneration. Recent technological advances in spatial transcriptomics (ST) provide a unique opportunity to decipher most genes systematically throughout scar formation, which remains poorly understood. Here, we first constructed the tissue-wide gene expression patterns of mouse spinal cords over the course of scar formation using ST after spinal cord injury from 32 samples. Locally, we profiled gene expression gradients from the leading edge to the core of the scar areas to further understand the scar microenvironment, such as neurotransmitter disorders, activation of the pro-inflammatory response, neurotoxic saturated lipids, angiogenesis, obstructed axon extension, and extracellular structure re-organization. In addition, we described 21 cell transcriptional states during scar formation and delineated the origins, functional diversity, and possible trajectories of subpopulations of fibroblasts, glia, and immune cells. Specifically, we found some regulators in special cell types, such as Thbs1 and Col1a2 in macrophages, CD36 and Postn in fibroblasts, Plxnb2 and Nxpe3 in microglia, Clu in astrocytes, and CD74 in oligodendrocytes. Furthermore, salvianolic acid B, a blood-brain barrier permeation and CD36 inhibitor, was administered after surgery and found to remedy fibrosis. Subsequently, we described the extent of the scar boundary and profiled the bidirectional ligand-receptor interactions at the neighboring cluster boundary, contributing to maintain scar architecture during gliosis and fibrosis, and found that GPR37L1_PSAP, and GPR37_PSAP were the most significant gene-pairs among microglia, fibroblasts, and astrocytes. Last, we quantified the fraction of scar-resident cells and proposed four possible phases of scar formation: macrophage infiltration, proliferation and differentiation of scar-resident cells, scar emergence, and scar stationary. Together, these profiles delineated the spatial heterogeneity of the scar, confirmed the previous concepts about scar architecture, provided some new clues for scar formation, and served as a valuable resource for the treatment of central nervous system injury.

Biocompatibility and biosafety of butterfly wings for the clinical use of tissue-engineered nerve grafts.

In a previous study, we used natural butterfly wings as a cell growth matrix for tissue engineering materials and found that the surface of different butterfly wings had different ultramicrostructures, which can affect the qualitative growth of cells and regulate cell growth, metabolism, and gene expression. However, the biocompatibility and biosafety of butterfly wings must be studied. In this study, we found that Sprague-Dawley rat dorsal root ganglion neurons could grow along the structural stripes of butterfly wings, and Schwann cells could normally attach to and proliferate on different species of butterfly wings. The biocompatibility and biosafety of butterfly wings were further examined through subcutaneous implantation in Sprague-Dawley rats, intraperitoneal injection in Institute of Cancer Research mice, intradermal injection in rabbits, and external application to guinea pigs. Our results showed that butterfly wings did not induce toxicity, and all examined animals exhibited normal behaviors and no symptoms, such as erythema or edema. These findings suggested that butterfly wings possess excellent biocompatibility and biosafety and can be used as a type of tissue engineering material. This study was approved by the Experimental Animal Ethics Committee of Jiangsu Province of China (approval No. 20190303-18) on March 3, 2019.

Achyranthes bidentata polypeptides prevent apoptosis by inhibiting the glutamate current in cultured hippocampal neurons.

Glutamate-induced excitotoxicity plays a critical role in the neurological impairment caused by middle cerebral artery occlusion. Achyranthes bidentata polypeptides have been shown to protect against neurological functional damage caused by middle cerebral artery occlusion, but the underlying neuroprotective mechanisms and the relationship to glutamate-induced excitotoxicity remain unclear. Therefore, in the current study, we investigated the protective effects of Achyranthes bidentata polypeptides against glutamate-induced excitotoxicity in cultured hippocampal neurons. Hippocampal neurons were treated with Mg2+-free extracellular solution containing glutamate (300 µM) for 3 hours as a model of glutamate-mediated excitotoxicity (glutamate group). In the normal group, hippocampal neurons were incubated in Mg2+-free extracellular solution. In the Achyranthes bidentata polypeptide group, hippocampal neurons were incubated in Mg2+-free extracellular solution containing glutamate (300 µM) and Achyranthes bidentata polypeptide at different concentrations. At 24 hours after exposure to the agents, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and Hoechst 33258 staining were used to assess neuronal viability and nuclear morphology, respectively. Caspase-3 expression and activity were evaluated using western blot assay and colorimetric enzymatic assay, respectively. At various time points after glutamate treatment, reactive oxygen species in cells were detected by H2DCF-DA, and mitochondrial membrane potential was detected by rhodamine 123 staining. To examine the effect of Achyranthes bidentata polypeptides on glutamate receptors, electrophysiological recording was used to measure the glutamate-induced inward current in cultured hippocampal neurons. Achyranthes bidentata polypeptide decreased the percentage of apoptotic cells and reduced the changes in caspase-3 expression and activity induced by glutamate. In addition, Achyranthes bidentata polypeptide attenuated the amplitude of the glutamate-induced current. Furthermore, the glutamate-induced increase in intracellular reactive oxygen species and reduction in mitochondrial membrane potential were attenuated by Achyranthes bidentata polypeptide treatment. These findings collectively suggest that Achyranthes bidentata polypeptides exert a neuroprotective effect in cultured hippocampal neurons by suppressing the overactivation of glutamate receptors and inhibiting the caspase-3-dependent mitochondrial apoptotic pathway. All animal studies were approved by the Animal Care and Use Committee, Nantong University, China (approval No. 20120216-001) on February 16, 2012.