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Anti-Inflammatory Mechanism of Neural Stem Cell Transplantation in Spinal Cord Injury

View Article: PubMed Central - PubMed

ABSTRACT

Neural stem cell (NSC) transplantation has been proposed to promote functional recovery after spinal cord injury. However, a detailed understanding of the mechanisms of how NSCs exert their therapeutic plasticity is lacking. We transplanted mouse NSCs into the injured spinal cord seven days after SCI, and the Basso Mouse Scale (BMS) score was performed to assess locomotor function. The anti-inflammatory effects of NSC transplantation was analyzed by immunofluorescence staining of neutrophil and macrophages and the detection of mRNA levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and interleukin-12 (IL-12). Furthermore, bone marrow-derived macrophages (BMDMs) were co-cultured with NSCs and followed by analyzing the mRNA levels of inducible nitric oxide synthase (iNOS), TNF-α, IL-1β, IL-6 and IL-10 with quantitative real-time PCR. The production of TNF-α and IL-1β by BMDMs was examined using the enzyme-linked immunosorbent assay (ELISA). Transplanted NSCs had significantly increased BMS scores (p < 0.05). Histological results showed that the grafted NSCs migrated from the injection site toward the injured area. NSCs transplantation significantly reduced the number of neutrophils and iNOS+/Mac-2+ cells at the epicenter of the injured area (p < 0.05). Meanwhile, mRNA levels of TNF-α, IL-1β, IL-6 and IL-12 in the NSCs transplantation group were significantly decreased compared to the control group. Furthermore, NSCs inhibited the iNOS expression of BMDMs and the release of inflammatory factors by macrophages in vitro (p < 0.05). These results suggest that NSC transplantation could modulate SCI-induced inflammatory responses and enhance neurological function after SCI via reducing M1 macrophage activation and infiltrating neutrophils. Thus, this study provides a new insight into the mechanisms responsible for the anti-inflammatory effect of NSC transplantation after SCI.

No MeSH data available.


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Survival, migration and distribution of grafted NSCs in vivo. (A) Mosaic image of a longitudinally-sectioned spinal cord from the control group four weeks post-transplantation; (B) only F4/80-positive cells (red) were detected in the epicenter of injury area; (C) mosaic image of a longitudinally-sectioned spinal cord from the NSC group four weeks after transplantation; grafted NSCs migrated from the injection site toward injured area; (D) in the NSC group, both GFP-positive cells and F4/80-positive cells (red) were found in the epicenter of the injured area; (E) representative images of spinal cord sections in the NSC group at four week and six weeks after cell transplantation. Nuclei were stained with DAPI. Scale bar: 100 μm (A,C); and 20 μm (B,D,E).
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ijms-17-01380-f002: Survival, migration and distribution of grafted NSCs in vivo. (A) Mosaic image of a longitudinally-sectioned spinal cord from the control group four weeks post-transplantation; (B) only F4/80-positive cells (red) were detected in the epicenter of injury area; (C) mosaic image of a longitudinally-sectioned spinal cord from the NSC group four weeks after transplantation; grafted NSCs migrated from the injection site toward injured area; (D) in the NSC group, both GFP-positive cells and F4/80-positive cells (red) were found in the epicenter of the injured area; (E) representative images of spinal cord sections in the NSC group at four week and six weeks after cell transplantation. Nuclei were stained with DAPI. Scale bar: 100 μm (A,C); and 20 μm (B,D,E).

Mentions: Four weeks after transplantation, the migration and distribution of grafted NSCs with green fluorescent protein (GFP) in the injured spinal cord was observed by longitudinal section. Compared to the control group (Figure 2A,B), cells with the GFP signal were found in the area between the implantation site and injured area four weeks after NSC transplantation (Figure 2C). It has been reported that bone marrow-derived macrophages (BMDMs) could migrate to the injured site about three days after the injury and then accumulate at the epicenter of damaged spinal cord [21]. Therefore, the epicenter of the injured area was identified with many F4/80+ cells having a round cell morphology. As shown in Figure 2D, GFP-NSCs arrived at the lesion epicenter, while there were only F4/80-positive cells without GFP-positive cells within the epicenter of the injury area in the control group (Figure 2B). Then, compared to four weeks after NSC transplantation, the number of NSCs within the injured area was significantly decreased at six weeks post-transplantation (Figure 2E). Therefore, these results suggested that grafted NSCs can survive and migrate toward the injured area.


Anti-Inflammatory Mechanism of Neural Stem Cell Transplantation in Spinal Cord Injury
Survival, migration and distribution of grafted NSCs in vivo. (A) Mosaic image of a longitudinally-sectioned spinal cord from the control group four weeks post-transplantation; (B) only F4/80-positive cells (red) were detected in the epicenter of injury area; (C) mosaic image of a longitudinally-sectioned spinal cord from the NSC group four weeks after transplantation; grafted NSCs migrated from the injection site toward injured area; (D) in the NSC group, both GFP-positive cells and F4/80-positive cells (red) were found in the epicenter of the injured area; (E) representative images of spinal cord sections in the NSC group at four week and six weeks after cell transplantation. Nuclei were stained with DAPI. Scale bar: 100 μm (A,C); and 20 μm (B,D,E).
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ijms-17-01380-f002: Survival, migration and distribution of grafted NSCs in vivo. (A) Mosaic image of a longitudinally-sectioned spinal cord from the control group four weeks post-transplantation; (B) only F4/80-positive cells (red) were detected in the epicenter of injury area; (C) mosaic image of a longitudinally-sectioned spinal cord from the NSC group four weeks after transplantation; grafted NSCs migrated from the injection site toward injured area; (D) in the NSC group, both GFP-positive cells and F4/80-positive cells (red) were found in the epicenter of the injured area; (E) representative images of spinal cord sections in the NSC group at four week and six weeks after cell transplantation. Nuclei were stained with DAPI. Scale bar: 100 μm (A,C); and 20 μm (B,D,E).
Mentions: Four weeks after transplantation, the migration and distribution of grafted NSCs with green fluorescent protein (GFP) in the injured spinal cord was observed by longitudinal section. Compared to the control group (Figure 2A,B), cells with the GFP signal were found in the area between the implantation site and injured area four weeks after NSC transplantation (Figure 2C). It has been reported that bone marrow-derived macrophages (BMDMs) could migrate to the injured site about three days after the injury and then accumulate at the epicenter of damaged spinal cord [21]. Therefore, the epicenter of the injured area was identified with many F4/80+ cells having a round cell morphology. As shown in Figure 2D, GFP-NSCs arrived at the lesion epicenter, while there were only F4/80-positive cells without GFP-positive cells within the epicenter of the injury area in the control group (Figure 2B). Then, compared to four weeks after NSC transplantation, the number of NSCs within the injured area was significantly decreased at six weeks post-transplantation (Figure 2E). Therefore, these results suggested that grafted NSCs can survive and migrate toward the injured area.

View Article: PubMed Central - PubMed

ABSTRACT

Neural stem cell (NSC) transplantation has been proposed to promote functional recovery after spinal cord injury. However, a detailed understanding of the mechanisms of how NSCs exert their therapeutic plasticity is lacking. We transplanted mouse NSCs into the injured spinal cord seven days after SCI, and the Basso Mouse Scale (BMS) score was performed to assess locomotor function. The anti-inflammatory effects of NSC transplantation was analyzed by immunofluorescence staining of neutrophil and macrophages and the detection of mRNA levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and interleukin-12 (IL-12). Furthermore, bone marrow-derived macrophages (BMDMs) were co-cultured with NSCs and followed by analyzing the mRNA levels of inducible nitric oxide synthase (iNOS), TNF-α, IL-1β, IL-6 and IL-10 with quantitative real-time PCR. The production of TNF-α and IL-1β by BMDMs was examined using the enzyme-linked immunosorbent assay (ELISA). Transplanted NSCs had significantly increased BMS scores (p < 0.05). Histological results showed that the grafted NSCs migrated from the injection site toward the injured area. NSCs transplantation significantly reduced the number of neutrophils and iNOS+/Mac-2+ cells at the epicenter of the injured area (p < 0.05). Meanwhile, mRNA levels of TNF-α, IL-1β, IL-6 and IL-12 in the NSCs transplantation group were significantly decreased compared to the control group. Furthermore, NSCs inhibited the iNOS expression of BMDMs and the release of inflammatory factors by macrophages in vitro (p < 0.05). These results suggest that NSC transplantation could modulate SCI-induced inflammatory responses and enhance neurological function after SCI via reducing M1 macrophage activation and infiltrating neutrophils. Thus, this study provides a new insight into the mechanisms responsible for the anti-inflammatory effect of NSC transplantation after SCI.

No MeSH data available.


Related in: MedlinePlus