Intra-arterial transplantation of human bone marrow mesenchymal stem cells (hBMMSCs) improves behavioral deficits and alters gene expression in rodent stroke model

The role of mesenchymal stem cell transplantation for ischemic stroke and recent research developments

Ischemic stroke is a common cerebrovascular disease that seriously affects human health. However, most patients do not practice self-care and cannot rely on the current clinical treatment for guaranteed functional recovery. Stem cell transplantation is an emerging treatment studied in various central nervous system diseases. More importantly, animal studies show that transplantation of mesenchymal stem cells (MSCs) can alleviate neurological deficits and bring hope to patients suffering from ischemic stroke. This paper reviews the biological characteristics of MSCs and discusses the mechanism and progression of MSC transplantation to provide new therapeutic directions for ischemic stroke.

Human Umbilical Cord-Derived Mesenchymal Stem Cell Therapy Effectively Protected the Brain Architecture and Neurological Function in Rat After Acute Traumatic Brain Injury

Intracranial hemorrhage from stroke and head trauma elicits a cascade of inflammatory and immune reactions detrimental to neurological integrity and function at cellular and molecular levels. This study tested the hypothesis that human umbilical cord–derived mesenchymal stem cell (HUCDMSC) therapy effectively protected the brain integrity and neurological function in rat after acute traumatic brain injury (TBI). Adult male Sprague-Dawley rats (n = 30) were equally divided into group 1 (sham-operated control), group 2 (TBI), and group 3 [TBI + HUCDMSC (1.2 × 10⁶ cells/intravenous injection at 3 h after TBI)] and euthanized by day 28 after TBI procedure. The results of corner test and inclined plane test showed the neurological function was significantly progressively improved from days 3, 7, 14, and 28 in groups 1 and 3 than in group 2, and group 1 than in group 3 (all P < 0.001). By day 28, brain magnetic resonance imaging brain ischemic volume was significantly increased in group 2 than in group 3 (P < 0.001). The protein expressions of apoptosis [mitochondrial-bax positive cells (Bax)/cleaved-caspase3/cleaved-poly(adenosine diphosphate (ADP)-ribose) polymerase], fibrosis (Smad3 positive cells (Smad3)/transforming growth factor-β), oxidative stress (NADPH Oxidase 1 (NOX-1)/NADPH Oxidase 2 (NOX-2)/oxidized-protein/cytochrome b-245 alpha chain (p22phox)), and brain-edema/deoxyribonucleic acid (DNA)–damaged biomarkers (Aquaporin-4/gamma H2A histone family member X ( (γ-H2AX)) displayed an identical pattern to neurological function among the three groups (all P < 0.0001), whereas the protein expressions of angiogenesis biomarkers (vascular endothelial growth factor/stromal cell–derived factor-1α/C-X-C chemokine receptor type 4 (CXCR4)) significantly increased from groups 1 to 3 (all P < 0.0001). The cellular expressions of inflammatory biomarkers (cluster of differentiation 14 (+) cells (CD14+)/glial fibrillary acidic protein positive cells (GFAP+)/ a member of a new family of EGF-TM7 molecules positive cells (F4/80+)) and DNA-damaged parameter (γ-H2AX) exhibited an identical pattern, whereas cellular expressions of neural integrity (hexaribonucleotide Binding Protein-3 positive cells (NeuN+)/nestin+/doublecortin+) exhibited an opposite pattern of neurological function among the three groups (all P < 0.0001). Xenogeneic HUCDMSC therapy was safe and it significantly preserved neurological function and brain architecture in rat after TBI.

Anti-inflammatory protein TSG-6 secreted by bone marrow mesenchymal stem cells attenuates neuropathic pain by inhibiting the TLR2/MyD88/NF-κB signaling pathway in spinal microglia

Background

Neuroinflammation plays a vital role in the development and maintenance of neuropathic pain. Recent evidence has proved that bone marrow mesenchymal stem cells (BMSCs) can inhibit neuropathic pain and possess potent immunomodulatory and immunosuppressive properties via secreting a variety of bioactive molecules, such as TNF-α-stimulated gene 6 protein (TSG-6). However, it is unknown whether BMSCs exert their analgesic effect against neuropathic pain by secreting TSG-6. Therefore, the present study aimed to evaluate the analgesic effects of TSG-6 released from BMSCs on neuropathic pain induced by chronic constriction injury (CCI) in rats and explored the possible underlying mechanisms in vitro and in vivo.

Methods

BMSCs were isolated from rat bone marrow and characterized by flow cytometry and functional differentiation. One day after CCI surgery, about 5 × 10⁶ BMSCs were intrathecally injected into spinal cerebrospinal fluid. Behavioral tests, including mechanical allodynia, thermal hyperalgesia, and motor function, were carried out at 1, 3, 5, 7, 14 days after CCI surgery. Spinal cords were processed for immunohistochemical analysis of the microglial marker Iba-1. The mRNA and protein levels of pro-inflammatory cytokines (IL-1β, TNFα, IL-6) were detected by real-time RT-PCR and ELISA. The activation of the TLR2/MyD88/NF-κB signaling pathway was evaluated by Western blot and immunofluorescence staining. The analgesic effect of exogenous recombinant TSG-6 on CCI-induced mechanical allodynia and heat hyperalgesia was observed by behavioral tests. In the in vitro experiments, primary cultured microglia were stimulated with the TLR2 agonist Pam3CSK4, and then co-cultured with BMSCs or recombinant TSG-6. The protein expression of TLR2, MyD88, p-p65 was evaluated by Western blot. The mRNA and protein levels of IL-1β, TNFα, IL-6 were detected by real-time RT-PCR and ELISA. BMSCs were transfected with the TSG-6-specific shRNA and then intrathecally injected into spinal cerebrospinal fluid in vivo or co-cultured with Pam3CSK4-treated primary microglia in vitro to investigate whether TSG-6 participated in the therapeutic effect of BMSCs on CCI-induced neuropathic pain and neuroinflammation.

Results

We found that CCI-induced mechanical allodynia and heat hyperalgesia were ameliorated by intrathecal injection of BMSCs. Moreover, intrathecal administration of BMSCs inhibited CCI-induced neuroinflammation in spinal cord tissues. The analgesic effect and anti-inflammatory property of BMSCs were attenuated when TSG-6 expression was silenced. We also found that BMSCs inhibited the activation of the TLR2/MyD88/NF-κB pathway in the ipsilateral spinal cord dorsal horn by secreting TSG-6. Meanwhile, we proved that intrathecal injection of exogenous recombinant TSG-6 effectively attenuated CCI-induced neuropathic pain. Furthermore, in vitro experiments showed that BMSCs and TSG-6 downregulated the TLR2/MyD88/NF-κB signaling and reduced the production of pro-inflammatory cytokines, such as IL-1β, IL-6, and TNF-α, in primary microglia treated with the specific TLR2 agonist Pam3CSK4.

Conclusions

The present study demonstrated a paracrine mechanism by which intrathecal injection of BMSCs targets the TLR2/MyD88/NF-κB pathway in spinal cord dorsal horn microglia to elicit neuroprotection and sustained neuropathic pain relief via TSG-6 secretion.

Mesenchymal Stem Cell Therapy in Stroke: A Systematic Review of Literature in Pre-Clinical and Clinical Research

Exogenous stem cell therapy (SCT) has been recognized recently as a promising neuroregenerative strategy to augment recovery in stroke survivors. Mesenchymal stem cells (MSCs) are the primary source of stem cells used in the majority of both pre-clinical and clinical studies in stroke. In the absence of evidence-based guidelines on the use of SCT in stroke patients, understanding the progress of MSC research across published studies will assist researchers and clinicians in better achieving success in translating research. We conducted a systematic review on published literature using MSCs in both pre-clinical studies and clinical trials between 2008 and 2017 using the public databases PubMed and Ovid Medline, and the clinical trial registry ( www.clinicaltrials.gov ). A total of 78 pre-clinical studies and eight clinical studies were identified. While majority of the pre-clinical and clinical studies demonstrated statistically significant effects, the clinical significance of these findings was still unclear. Effect sizes could not be measured mainly due to reporting issues in pre-clinical studies, thus limiting our ability to compare results across studies quantitatively. The overall quality of both pre-clinical and clinical studies was sub-optimal. By conducting a systematic review of both pre-clinical and clinical studies on MSCs therapy in stroke, we assessed the quality of current evidence and identified several issues and gaps in translating animal studies to human trials. Addressing these issues and incorporating changes into future animal studies and human trials may lead to better success of stem cells-based therapeutics in the near future.

Effects of Dl-3-n-butylphthalide on Cerebral Ischemia Infarction in Rat Model by Mass Spectrometry Imaging

Dl-3-n-butylphthalide (NBP) is a drug that is used in the treatment of ischaemic stroke. However, to the best of our knowledge, there are no systematic studies investigating the effects of dl-3-n-butylphtalide on the brain metabolism of small molecules. In this study, we first investigated the effects of dl-3-n-butylphthalide on the spatial distribution of small molecules in the brains of rats with permanent middle cerebral artery occlusion (pMCAO) using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI–TOF–MS) imaging. After pMCAO modelling or a sham operation, rats were given four mg/kg of dl-3-n-butylphthalide through the caudal vein or saline once a day for nine days. The degree of neurological deficit in rats was evaluated using the modified neurological severity score (mNSS). MALDI–TOF–MS imaging was used to observe the content and distribution of small molecules related to metabolism during focal cerebral ischaemia. Multiple reaction monitoring (MRM) mode with liquid chromatography tandem mass spectrometry (LC–MS/MS) was used to verify the results obtained from MALDI–TOF–MS imaging. These small molecules were found to be involved in glucose metabolism, ATP metabolism, the glutamate–glutamine cycle, malate aspartate shuttle, oxidative stress, and inorganic ion homeostasis. Of the 13 metabolites identified by MALDI–TOF–MS imaging, seven compounds, ATP, ADP, AMP, GMP, N-acetylaspartic acid, ascorbic acid and glutathione, were further validated by LC–MS/MS. Taken together, these results indicate that dl-3-n-butylphthalide significantly improved ATP metabolism, level of antioxidants, and sodium-potassium ion balance in a rat model of pMCAO.