Photoluminescent Mesoporous Silicon Nanoparticles with siCCR2 Improve the Effects of Mesenchymal Stromal Cell Transplantation after Acute Myocardial Infarction.
Photoluminescent Mesoporous Silicon Nanoparticles with siCCR2 Improve the Effects of Mesenchymal Stromal Cell Transplantation after Acute Myocardial Infarction.
复制标题
带有siCCR2的光致发光介孔硅纳米粒子改善急性心肌梗塞后间充质基质细胞移植的效果
作者：
Lu W;Xie Z;Tang Y;Bai L;Yao Y;Fu C;Ma G
背景：尽管间充质间质细胞（MSC）移植在心脏组织中有益处，但详细的体内观察表明，由于梗死心肌中恶劣的微环境条件，包括缺血、炎症和损伤，MSC在移植后只能存活很短的时间。因此，需要新的策略来提高MSC的存活和抑制心脏重塑。目前的研究表明，趋化因子[C-C基序]配体2 （CCL2）及其同源受体C-C趋化因子受体2 （CCR2）在缺血性心肌损伤反应中促进梗死区过度的ly6high炎性单核细胞浸润。因此，在急性心肌梗死（AMI）后立即降低这些单核细胞的活性可能对AMI患者有益。目的：本研究验证了靶向ly6高炎性单核细胞CCR2表达的sirna负载的治疗性光致发光介孔硅纳米颗粒（PMSNs）可减少这些细胞在梗死区聚集，提高间充质干细胞移植的疗效，减轻心肌重构的假设。方法：首次合成携带治疗性siCCR2的pmsn，不含荧光材料或染料。AMI BALB/c小鼠建立后，将105个5-乙基-2′-脱氧尿苷（EdU）标记的MSCs悬于100µl磷酸缓冲盐水（PBS）中，注射到每只小鼠的梗死边界区。AMI诱导后立即经尾静脉静脉注射pmsn - siccr2（25µg/g）。对照小鼠注射等量的不含siCCR2的pmsn。采用近红外成像技术对pmsn - siccr2进行体内检测。从mRNA、蛋白和功能水平检测pmsn - siccr2对MSC移植的治疗作用。结果：pmsn - siccr2在体内自由循环，并在相对较短的时间内（t½=37 min）被清除，无毒性证据。与对照组相比，治疗组pmsn - siccr2在脾脏ly6 - high单核细胞中的细胞积累水平更高，CCR2的降解效率更高（8.04%±2.17%比20.02%±4.55%,p<0.001）。随后，pmsn - siccr2在第1天降低了梗死区cd11b阳性单核细胞的积累（49.3%±17.34% vs. 61.32%±22.43%,p<0.001）。pmsn - siccr2组在AMI诱导3天后梗死区移植MSCs的存活率增加（13±3/mm2 vs. 4±1/mm2, p<0.001）， tdt介导的dUTP缺口末端标记(TUNEL)+心肌细胞的存活率显著降低（17.44%±6.26% vs. 39.49%±13.28%,p<0.001）。注射MSC后3周，心肌梗死边界区血管密度（235.5±39.6/mm2 vs. 147.4±20.3/mm2, p<0.001）和心肌肌球蛋白阳性面积（21.7%±8.4% vs. 13.2%±4.4%,p<0.001）显著增加。此外，与对照组相比，左室重构（左室后壁厚度）（0.84±0.11 mm vs 0.61±0.08 mm, p<0.001）也有显著改善。结论：pmsn - siccr2介导的ly6high单核细胞CCR2基因沉默提高了间充质干细胞移植的有效性，并选择性地改善了AMI后心肌重构。这些结果表明，pmsn - siccr2可能用于ami后MSC移植的抗炎治疗。
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 Ly6Chigh 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 Ly6Chigh 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, 105 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 (t½=37 min) with no evidence of toxicity. The therapeutic PMSNs-siCCR2 showed higher levels of cellular accumulation in Ly6Chigh 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/mm2 vs. 4±1/mm2, 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/mm2 vs. 147.4±20.3/mm2, 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 Ly6Chigh 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.