Neural Stem Cells Grafts Decrease Neural Apoptosis Associated with Caspase-7 Downregulation and BDNF Upregulation in Rats Following Spinal Cord Hemisection

lncfos/miR-212-5p/CASP7 Axis-Regulated miR-212-5p Protects the Brain Against Ischemic Damage

miR-212-5p has been reported to be involved in many biological processes. However, the role of miR-212-5p in ischemic stroke remains unclear. This study explored the biological role and potential mechanism of miR-212-5p in ischemic stroke by investigating the lncfos/miR-212-5p/CASP7 axis. A total of 32 patients with ischemic stroke and 32 age- and sex-matched healthy controls (HCs) were enrolled in this study. In addition, 336 rats were used in this study. The rats were subjected to middle cerebral artery occlusion (MCAO) and intracerebroventricular injection of a microRNA (miRNA) agomir, a miRNA antagomir, a short hairpin RNA (shRNA) lentiviral vector, or a negative control. The neurological deficit score was calculated; the infarct volume was measured; histopathological assays were performed; the neuronal apoptosis rate was determined; and the lncfos, miR-212-5p, and CASP7 expression levels in the peri-infarct area were assessed. In this study, we found that the expression level of miR-212-5p was significantly downregulated in the peri-infarct area and blood of the MCAO model rats and the blood of patients with ischemic stroke. A double-luciferase experiment showed that CASP7 was a direct target gene of miR-212-5p and that miR-212-5p was a target miRNA of lncfos. Lateral ventricular injection of the miR-212-5p agomir effectively inhibited the apoptosis induced by ischemic brain damage, reduced the infarct volume, attenuated the neurological deficit symptoms, and downregulated the expression of CASP7 in the peri-infarct area of the MCAO model rats. Suppressing lncfos with sh-fos led to the upregulated expression of miR-212-5p and played a neuroprotective role in the rat MCAO models. We concluded that miR-212-5p plays a neuroprotective role in ischemic stroke and that its function is regulated by the lncfos/miR-212-5p/CASP7 axis. Moreover, miR-212-5p may be a potential biomarker and therapeutic target for ischemic stroke.

Neural Stem Cell Transplantation Improves Locomotor Function in Spinal Cord Transection Rats Associated with Nerve Regeneration and IGF-1 R Expression

Transplantation of neural stem cells (NSCs) is a potential strategy for the treatment of spinal cord transection (SCT). Here we investigated whether transplanted NSCs would improve motor function of rats with SCT and explored the underlying mechanism. First, the rats were divided into sham, SCT, and NSC groups. Rats in the SCT and NSC groups were all subjected to SCT in T10, and were administered with media and NSC transplantation into the lesion site, respectively. Immunohistochemistry was used to label Nestin-, TUNEL-, and NeuN-positive cells and reveal the expression and location of type I insulin-like growth factor receptor (IGF-1 R). Locomotor function of hind limbs was assessed by Basso, Beattie, Bresnahan (BBB) score and inclined plane test. The conduction velocity and amplitude of spinal nerve fibers were measured by electrophysiology and the anatomical changes were measured using magnetic resonance imaging. Moreover, expression of IGF-1 R was determined by real-time polymerase chain reaction and Western blotting. The results showed that NSCs could survive and differentiate into neurons in vitro and in vivo. SCT-induced deficits were reduced by NSC transplantation, including increase in NeuN-positive cells and decrease in apoptotic cells. Moreover, neurophysiological profiles indicated that the latent period was decreased and the peak-to-peak amplitude of spinal nerve fibers conduction was increased in transplanted rats, while morphological measures indicated that fractional anisotropy and the number of nerve fibers in the site of spinal cord injury were increased after NSC transplantation. In addition, mRNA and protein level of IGF-1 R were increased in the rostral segment in the NSC group, especially in neurons. Therefore, we concluded that NSC transplantation promotes motor function improvement of SCT, which might be associated with activated IGF-1 R, especially in the rostral site. All of the above suggests that this approach has potential for clinical treatment of spinal cord injury.

Co-Transplantation of Human Umbilical Cord Mesenchymal Stem Cells and Human Neural Stem Cells Improves the Outcome in Rats with Spinal Cord Injury

Neural stem cells (NSCs) and mesenchymal stem cells (MSCs) are promising graft materials for cell therapies in spinal cord injury (SCI) models. Previous studies have demonstrated that MSCs can regulate the microenvironment of NSCs and promote their survival rate. Furthermore, several studies indicate that MSCs can reduce stem cell transplantation-linked tumor formation. To our knowledge, no previous studies have determined whether co-transplantation of human umbilical cord mesenchymal stem cells (hUC-MSCs) and human neural stem cells (hNSCs) could improve the outcome in rats with SCI. Therefore, we investigated whether the transplantation of hUC-MSCs combined with hNSCs through an intramedullary injection can improve the outcome of rats with SCI, and explored the underlying mechanisms. In this study, a moderate spinal cord contusion model was established in adult female Wistar rats using an NYU impactor. In total, 108 spinal cord-injured rats were randomly selected and divided into the following five groups: 1) hUC-MSCs group, 2) hNSCs group, 3) hUC-MSCs+hNSCs group, 4) PBS (control) group, and 5) a Sham group. Basso, Beattie and Bresnahan (BBB) behavioral test scores were used to evaluate the motor function of all animals before and after the SCI weekly through the 8th week. Two weeks after transplantation, some rats were sacrificed, immunofluorescence and immunohistochemistry were performed to evaluate the survival and differentiation of the transplanted stem cells, and brain-derived neurotrophic factor (BDNF) was detected by ELISA in the injured spinal cords. At the end of the experiment, we evaluated the remaining myelin sheath and anterior horn neurons in the injured spinal cords using Luxol Fast Blue (LFB) staining. Our results demonstrated that the surviving stem cells in the hUC-MSCs+hNSCs group were significantly increased compared with those in the hUC-MSCs alone and the hNSCs alone groups 2 weeks post-transplantation. Furthermore, the results of the BBB scores and the remaining myelin sheath evaluated via LFB staining in the injured spinal cords demonstrated that the most significantly improved outcome occurred in the hUC-MSCs+hNSCs group. The hUC-MSCs alone and the hNSCs alone groups also had a better outcome compared with that of the PBS-treated group. In conclusion, the present study demonstrates that local intramedullary subacute transplantation of hUC-MSCs, hNSCs, or hUC-MSCs+hNSCs significantly improves the outcome in an in vivo moderate contusion SCI model, and that co-transplantation of hUC-MSCs and hNSCs displayed the best outcome in our experiment.

Recombinant human brain-derived neurotrophic factor prevents neuronal apoptosis in a novel in vitro model of subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a hemorrhagic stroke with high mortality and morbidity. An animal model for SAH was established by directly injecting a hemolysate into the subarachnoid space of rats or mice. However, the in vitro applications of the hemolysate SAH model have not been reported, and the mechanisms remain unclear. In this study, we established an in vitro SAH model by treating cortical pyramidal neurons with hemolysate. Using this model, we assessed the effects of recombinant human brain-derived neurotrophic factor (rhBDNF) on hemolysate-induced cell death and related mechanisms. Cortical neurons were treated with 10 ng/mL or 100 ng/mL rhBDNF prior to application of hemolysate. Hemolysate treatment markedly increased cell loss, triggered apoptosis, and promoted the expression of caspase-8, caspase-9, and cleaved caspase-3. rhBDNF significantly inhibited hemolysate-induced cell loss, neuronal apoptosis, and expression of caspase-8, caspase-9, and cleaved caspase-3. Our data revealed a previously unrecognized protective activity of rhBDNF against hemolysate-induced cell death, potentially via regulation of caspase-9-, caspase-8-, and cleaved caspase-3-related apoptosis. This study implicates that hemolysate-induced cortical neuron death represents an important in vitro model of SAH.

Direct lineage conversion of astrocytes to induced neural stem cells or neurons

Since the generation of induced pluripotent stem cells in 2006, cellular reprogramming has attracted increasing attention as a revolutionary strategy for cell replacement therapy. Recent advances have revealed that somatic cells can be directly converted into other mature cell types, which eliminates the risk of neoplasia and the generation of undesired cell types. Astrocytes become reactive and undergo proliferation, which hampers axon regeneration following injury, stroke, and neurodegenerative diseases. An emerging technique to directly reprogram astrocytes into induced neural stem cells (iNSCs) and induced neurons (iNs) by neural fate determinants brings potential hope to cell replacement therapy for the above neurological problems. Here, we discuss the development of direct reprogramming of various cell types into iNs and iNSCs, then detail astrocyte-derived iNSCs and iNs in vivo and in vitro. Finally, we highlight the unsolved challenges and opportunities for improvement.