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Photoluminescent Mesoporous Silicon Nanoparticles with siCCR2 Improve the Effects of Mesenchymal Stromal Cell Transplantation after Acute Myocardial Infarction.

Lu W, Xie Z, Tang Y, Bai L, Yao Y, Fu C, Ma G - Theranostics (2015)

Bottom Line: The therapeutic effects of PMSNs-siCCR2 for MSC transplantation were determined at the mRNA, protein and functional levels.In addition, significant amelioration of left ventricular (LV) remodeling (thickness of the LV posterior walls) (0.84±0.11 mm vs. 0.61±0.08 mm, p<0.001) was also observed at the same time compared with the control group.These results suggest that PMSNs-siCCR2 could potentially be used to develop an anti-inflammatory therapy for post-AMI MSC transplantation.

View Article: PubMed Central - PubMed

Affiliation: 1. Department of Cardiology, ZhongDa Hospital affiliated with Southeast University, China; ; 2. Department of Cardiology, the Second Hospital affiliated with Southeast University, China;

ABSTRACT

Background: Despite the benefits of mesenchymal stromal cell (MSC) transplantation in cardiac tissue, detailed in vivo observations have shown that MSCs only survive for a brief period after transplantation due to harsh microenvironmental conditions, including ischemia, inflammation and anoikis, in the infarcted myocardium. Thus, new strategies are needed to enhance MSC survival and inhibit cardiac remodeling. Studies have now demonstrated that chemokine [C-C motif] ligand 2 (CCL2) and its cognate receptor C-C chemokine receptor 2 (CCR2) promote excessive Ly6C(high) inflammatory monocyte infiltration at the infarct in response to ischemic myocardial injury. Therefore, decreasing the activities of these monocytes immediately after acute myocardial infarction (AMI) could be beneficial for AMI patients.

Objectives: This study tested the hypothesis that therapeutic siRNA-loaded photoluminescent mesoporous silicon nanoparticles (PMSNs) targeting CCR2 expression in Ly6C(high) inflammatory monocytes decrease the accumulation of these cells in the infarct, improve the efficacy of MSC transplantation and attenuate myocardial remodeling.

Methods: PMSNs carrying therapeutic siCCR2 were first synthesized without the inclusion of fluorescent materials or dyes. After AMI BALB/c mice were established, 10(5) 5-ethynyl-2'- deoxyuridine (EdU)-labeled MSCs suspended in 100 µl of phosphate buffered saline (PBS) were injected into the border zone of the infarct of each mouse. PMSNs-siCCR2 (25 µg/g) were also intravenously injected via the tail vein immediately following AMI induction. Control mice were injected with an equal amount of PMSNs without siCCR2. PMSNs-siCCR2 were examined in vivo using near-infrared imaging technology. The therapeutic effects of PMSNs-siCCR2 for MSC transplantation were determined at the mRNA, protein and functional levels.

Results: PMSNs-siCCR2 circulated freely in vivo and were cleared in a relatively short period of time (t(½)=37 min) with no evidence of toxicity. The therapeutic PMSNs-siCCR2 showed higher levels of cellular accumulation in Ly6C(high) monocytes in the spleen and more efficient degradation of CCR2 compared with the control (8.04%±2.17% vs. 20.02%±4.55%, p<0.001). Subsequently, the PMSNs-siCCR2 decreased the accumulation of CD11b-positive monocytes at the infarct (49.3%±17.34% vs. 61.32%±22.43%, p<0.001) on day 1. Increased survival of transplanted MSCs (13±3/mm(2) vs. 4±1/mm(2), p<0.001) and significantly decreased TdT-mediated dUTP nick end labeling (TUNEL)(+) cardiac myocytes (17.44%±6.26% vs. 39.49%±13.28%, p<0.001) were then identified in the infarct zone three days after AMI induction in the PMSNs-siCCR2 group. Three weeks after MSC injection, significant increases were observed in the vascular density (235.5±39.6/mm(2) vs. 147.4±20.3/mm(2), p<0.001) and the cardiac myosin-positive area (21.7%±8.4% vs. 13.2%±4.4%, p<0.001) of the infarct border zone. In addition, significant amelioration of left ventricular (LV) remodeling (thickness of the LV posterior walls) (0.84±0.11 mm vs. 0.61±0.08 mm, p<0.001) was also observed at the same time compared with the control group.

Conclusions: PMSNs-siCCR2-mediated CCR2 gene silencing in Ly6C(high) monocytes improved the effectiveness of MSC transplantation and selectively ameliorated myocardial remodeling after AMI. These results suggest that PMSNs-siCCR2 could potentially be used to develop an anti-inflammatory therapy for post-AMI MSC transplantation.

No MeSH data available.


Related in: MedlinePlus

Dynamic fluorescence imaging of the distribution and metabolism of PMSNs-siCCR2-PEI in vivo determined using a near-infrared imaging system (n=12). (a), In vivo images of PMSNs-siCCR2-PEI. The mice were imaged at multiple time points after intravenous injection of the compounds (25 mg/kg). The white and red arrowheads indicate the liver and spleen, respectively. Imaging the dynamic biodistribution of siCCR2 shows major uptake in the spleen and liver. (b), Fluorescence images showing the in vivo biodistribution of PMSNs-siCCR2 in the heart, liver, spleen, kidney and lung over time; the compounds are rapidly cleared from the blood in 12 hours and were excreted via the hepatobiliary and renal routes during this time. (c), Confocal laser scanning microscopy of the spleen red pulp shows colocalization of PMSNs-siCCR2 (red) and CD11b-expressing monocytes (green). (d), Immunofluorescence microscopy of spleen sections reveals detached siCCR2 and PMSNs with green fluorescence and red fluorescence, respectively.
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Figure 3: Dynamic fluorescence imaging of the distribution and metabolism of PMSNs-siCCR2-PEI in vivo determined using a near-infrared imaging system (n=12). (a), In vivo images of PMSNs-siCCR2-PEI. The mice were imaged at multiple time points after intravenous injection of the compounds (25 mg/kg). The white and red arrowheads indicate the liver and spleen, respectively. Imaging the dynamic biodistribution of siCCR2 shows major uptake in the spleen and liver. (b), Fluorescence images showing the in vivo biodistribution of PMSNs-siCCR2 in the heart, liver, spleen, kidney and lung over time; the compounds are rapidly cleared from the blood in 12 hours and were excreted via the hepatobiliary and renal routes during this time. (c), Confocal laser scanning microscopy of the spleen red pulp shows colocalization of PMSNs-siCCR2 (red) and CD11b-expressing monocytes (green). (d), Immunofluorescence microscopy of spleen sections reveals detached siCCR2 and PMSNs with green fluorescence and red fluorescence, respectively.

Mentions: The specific siRNA sequence used in this study (5′-uGcuAAAcGucucuGcAAAdTsdT-3′, 5′- UUUGcAGAGACGUUuAGcAdTsdT-3′) to target CCR2 (siCCR2/fluorescent dye-labeled siCCR2, synthesized by Gene Pharma, China) was previously reported by Matthias Nahrendorf et al 24. After the siRNA was scaled up and encapsulated in the particles, the PMSNs-siCCR2-PEI were intravenously injected into AMI mice. In vivo data were acquired serially for up to 24 hours using near-infrared technology. Ten minutes after injection, a strong fluorescent signal was observed in the cardiac region and the circulation (0.0144±0.00214 scaled counts/s), reflecting the presence of PMSNs-siRNA-PEI in the blood. These nanoparticles accumulate and degrade quickly in the circulation, with a short half-life of 37 minutes (Fig. 3a).


Photoluminescent Mesoporous Silicon Nanoparticles with siCCR2 Improve the Effects of Mesenchymal Stromal Cell Transplantation after Acute Myocardial Infarction.

Lu W, Xie Z, Tang Y, Bai L, Yao Y, Fu C, Ma G - Theranostics (2015)

Dynamic fluorescence imaging of the distribution and metabolism of PMSNs-siCCR2-PEI in vivo determined using a near-infrared imaging system (n=12). (a), In vivo images of PMSNs-siCCR2-PEI. The mice were imaged at multiple time points after intravenous injection of the compounds (25 mg/kg). The white and red arrowheads indicate the liver and spleen, respectively. Imaging the dynamic biodistribution of siCCR2 shows major uptake in the spleen and liver. (b), Fluorescence images showing the in vivo biodistribution of PMSNs-siCCR2 in the heart, liver, spleen, kidney and lung over time; the compounds are rapidly cleared from the blood in 12 hours and were excreted via the hepatobiliary and renal routes during this time. (c), Confocal laser scanning microscopy of the spleen red pulp shows colocalization of PMSNs-siCCR2 (red) and CD11b-expressing monocytes (green). (d), Immunofluorescence microscopy of spleen sections reveals detached siCCR2 and PMSNs with green fluorescence and red fluorescence, respectively.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4508497&req=5

Figure 3: Dynamic fluorescence imaging of the distribution and metabolism of PMSNs-siCCR2-PEI in vivo determined using a near-infrared imaging system (n=12). (a), In vivo images of PMSNs-siCCR2-PEI. The mice were imaged at multiple time points after intravenous injection of the compounds (25 mg/kg). The white and red arrowheads indicate the liver and spleen, respectively. Imaging the dynamic biodistribution of siCCR2 shows major uptake in the spleen and liver. (b), Fluorescence images showing the in vivo biodistribution of PMSNs-siCCR2 in the heart, liver, spleen, kidney and lung over time; the compounds are rapidly cleared from the blood in 12 hours and were excreted via the hepatobiliary and renal routes during this time. (c), Confocal laser scanning microscopy of the spleen red pulp shows colocalization of PMSNs-siCCR2 (red) and CD11b-expressing monocytes (green). (d), Immunofluorescence microscopy of spleen sections reveals detached siCCR2 and PMSNs with green fluorescence and red fluorescence, respectively.
Mentions: The specific siRNA sequence used in this study (5′-uGcuAAAcGucucuGcAAAdTsdT-3′, 5′- UUUGcAGAGACGUUuAGcAdTsdT-3′) to target CCR2 (siCCR2/fluorescent dye-labeled siCCR2, synthesized by Gene Pharma, China) was previously reported by Matthias Nahrendorf et al 24. After the siRNA was scaled up and encapsulated in the particles, the PMSNs-siCCR2-PEI were intravenously injected into AMI mice. In vivo data were acquired serially for up to 24 hours using near-infrared technology. Ten minutes after injection, a strong fluorescent signal was observed in the cardiac region and the circulation (0.0144±0.00214 scaled counts/s), reflecting the presence of PMSNs-siRNA-PEI in the blood. These nanoparticles accumulate and degrade quickly in the circulation, with a short half-life of 37 minutes (Fig. 3a).

Bottom Line: The therapeutic effects of PMSNs-siCCR2 for MSC transplantation were determined at the mRNA, protein and functional levels.In addition, significant amelioration of left ventricular (LV) remodeling (thickness of the LV posterior walls) (0.84±0.11 mm vs. 0.61±0.08 mm, p<0.001) was also observed at the same time compared with the control group.These results suggest that PMSNs-siCCR2 could potentially be used to develop an anti-inflammatory therapy for post-AMI MSC transplantation.

View Article: PubMed Central - PubMed

Affiliation: 1. Department of Cardiology, ZhongDa Hospital affiliated with Southeast University, China; ; 2. Department of Cardiology, the Second Hospital affiliated with Southeast University, China;

ABSTRACT

Background: Despite the benefits of mesenchymal stromal cell (MSC) transplantation in cardiac tissue, detailed in vivo observations have shown that MSCs only survive for a brief period after transplantation due to harsh microenvironmental conditions, including ischemia, inflammation and anoikis, in the infarcted myocardium. Thus, new strategies are needed to enhance MSC survival and inhibit cardiac remodeling. Studies have now demonstrated that chemokine [C-C motif] ligand 2 (CCL2) and its cognate receptor C-C chemokine receptor 2 (CCR2) promote excessive Ly6C(high) inflammatory monocyte infiltration at the infarct in response to ischemic myocardial injury. Therefore, decreasing the activities of these monocytes immediately after acute myocardial infarction (AMI) could be beneficial for AMI patients.

Objectives: This study tested the hypothesis that therapeutic siRNA-loaded photoluminescent mesoporous silicon nanoparticles (PMSNs) targeting CCR2 expression in Ly6C(high) inflammatory monocytes decrease the accumulation of these cells in the infarct, improve the efficacy of MSC transplantation and attenuate myocardial remodeling.

Methods: PMSNs carrying therapeutic siCCR2 were first synthesized without the inclusion of fluorescent materials or dyes. After AMI BALB/c mice were established, 10(5) 5-ethynyl-2'- deoxyuridine (EdU)-labeled MSCs suspended in 100 µl of phosphate buffered saline (PBS) were injected into the border zone of the infarct of each mouse. PMSNs-siCCR2 (25 µg/g) were also intravenously injected via the tail vein immediately following AMI induction. Control mice were injected with an equal amount of PMSNs without siCCR2. PMSNs-siCCR2 were examined in vivo using near-infrared imaging technology. The therapeutic effects of PMSNs-siCCR2 for MSC transplantation were determined at the mRNA, protein and functional levels.

Results: PMSNs-siCCR2 circulated freely in vivo and were cleared in a relatively short period of time (t(½)=37 min) with no evidence of toxicity. The therapeutic PMSNs-siCCR2 showed higher levels of cellular accumulation in Ly6C(high) monocytes in the spleen and more efficient degradation of CCR2 compared with the control (8.04%±2.17% vs. 20.02%±4.55%, p<0.001). Subsequently, the PMSNs-siCCR2 decreased the accumulation of CD11b-positive monocytes at the infarct (49.3%±17.34% vs. 61.32%±22.43%, p<0.001) on day 1. Increased survival of transplanted MSCs (13±3/mm(2) vs. 4±1/mm(2), p<0.001) and significantly decreased TdT-mediated dUTP nick end labeling (TUNEL)(+) cardiac myocytes (17.44%±6.26% vs. 39.49%±13.28%, p<0.001) were then identified in the infarct zone three days after AMI induction in the PMSNs-siCCR2 group. Three weeks after MSC injection, significant increases were observed in the vascular density (235.5±39.6/mm(2) vs. 147.4±20.3/mm(2), p<0.001) and the cardiac myosin-positive area (21.7%±8.4% vs. 13.2%±4.4%, p<0.001) of the infarct border zone. In addition, significant amelioration of left ventricular (LV) remodeling (thickness of the LV posterior walls) (0.84±0.11 mm vs. 0.61±0.08 mm, p<0.001) was also observed at the same time compared with the control group.

Conclusions: PMSNs-siCCR2-mediated CCR2 gene silencing in Ly6C(high) monocytes improved the effectiveness of MSC transplantation and selectively ameliorated myocardial remodeling after AMI. These results suggest that PMSNs-siCCR2 could potentially be used to develop an anti-inflammatory therapy for post-AMI MSC transplantation.

No MeSH data available.


Related in: MedlinePlus