[Efficacy of subgroup mouse bone mesenchymal stem cells on mobilizing autologous cardiac stem cells and repairing ischemic myocardial tissue].

OBJECTIVE: To search for the bone mesenchymal stem cell (MSC) subgroup which might be more effective on repairing myocardial damage. METHODS: In this experiment, four MSC subgroups were defined based on the surface differentiation antigen detection of mouse bone mesenchymal stem cells (mBMSCs): SCA-1(+)/CD45(+)/CD31(+), SCA-1(+)/CD45(+)/CD31(-), SCA-1(+)/CD45(-)/CD31(-) and SCA-1(+)/CD45(-)/CD31(+). These subgroup cells and unselected mBMSCs were injected into infarcted mouse via tail vein. Echocardiographic heart function measurement and in vivo DiR-labeled stem cells imaging were performed at 48 h after injection. In situ C-kit (a flag antigen of cardiac stem cells) and cardiac-specific differentiation antigen immunohistochemistry detection was made in the infarcted myocardium. RESULTS: The capacity of the SCA-1(+)/CD45(+)/CD31(+) cells on improving heart function was significantly higher than other cell groups (all P < 0.05). In vivo imaging showed that the mean fluorescence intensity of the SCA-1(+)/CD45(+)/CD31(+) cells was also higher than other cell groups (all P < 0.05). Number of cardiac stem cells in the infracted myocardium was significantly increased after the injection of all subgroup cells and unsorted mBMSCs cells for 48 h compared untreated infracted myocardium. The capacity of mobilizing cardiac stem cells is as follows: SCA-1(+)/CD45(+)/CD31(+) >SCA-1(+)/CD45(-)/CD31(+) >SCA-1(+)/CD45(-)/CD31(-) >SCA-1(+)/CD45(+)/CD31(-). CONCLUSION: The SCA-1(+)/CD45(+)/CD31(+) subgroups of mBMSCs exhibites the highest capacity to improve cardiac function after myocardial infarction and to mobilize autologous cardiac stem cells compared with other mBMSCs subgroups and unsorted mBMSCs cells.

[The application of triple branches aortic arch stent-graft placement in the surgical treatment of acute Stanford type A aortic dissection].

OBJECTIVE: To sum up the experience of performing ascending aorta replacement combined triple-branched stent graft implantation for acute Stanford type A aortic dissection. METHODS: From January 2010 to December 2010, 14 patients with acute Stanford type A aortic dissection underwent the procedure of performing ascending aorta replacement combined triple-branched stent graft implantation. Right axillary artery cannulation was used for cardiopulmonary bypass and selected cerebral perfusion. When the body temperature drops below 18°C, the ascending aorta was transected near the base of the innominate artery. From the incision, the triple-branched stent graft was implanted into the true lumen of the arch, descending aorta and the aorta bifurcation vessel. The transected stump of the ascending aorta was anastomosis to the proximal of the branched blood vessel prosthesis. RESULTS: Cardiopulmonary bypass time was (186 ± 38) min, cross clamp time was (101 ± 27) min, and average selective cerebral perfusion and lower body arrest time was (39 ± 11) min. The in-hospital mortality was zero. One patient of transient postoperative neurologic dysfunction, one of acute renal failure, one of transient limbs disturbance, one of secondary thoracotomy operation, one of gastrointestinal hemorrhage and one of postoperative chylothorax were observed. CT angiography rechecked showed the position of the vascular stent were satisfactory and the blood flow of arterial branches stents were lucid. The false lumen of the aortic arch and descending aorta closed with thrombus or shrinked. CONCLUSIONS: The patients required aortic arch to be reconstructed which had no main tearing of intima in the arch may be best candidates for this technique. Open triple-branched stent graft placement combined ascending aorta replacement is an effective means for aortic arch reconstruction in acute Stanford type A aortic dissection.

MicroRNA-134-5p Regulates Media Degeneration through Inhibiting VSMC Phenotypic Switch and Migration in Thoracic Aortic Dissection.

Abnormal phenotypic switch, migration, and proliferation of vascular smooth muscle cells (VSMCs) are hallmarks for pathogenesis of thoracic aortic dissection (TAD). In the current study, we identified miR-134-5p as a critical regulator controlling human VSMC phenotypic switch and migration to investigate whether miR-134-5p affects human VSMC functions and development of TAD. Using miRNA microarray of aorta specimens from 12 TAD and 12 controls, we identified miR-134-5p, which was significantly downregulated in TAD tissues. With qPCR detection, we found that miR-134-5p was also evidently decreased in human AoSMCs. Ectopic expression of miR-134-5p obviously promoted VSMC differentiation and expression of contractile markers, such as α-SMA, SM22α, and MYH11. miR-134-5p potently inhibited PDGF-BB-induced VSMC phenotypic switch and migration. We further identified STAT5B and ITGB1 as downstream targets of miR-134-5p in human VSMCs and proved them to be mediators in VSMC phenotypic switch and progression of TAD. Finally, Ad-miR-134-5p obviously suppressed the aorta dilatation and vascular media degeneration by 39% in TAD mice after vascular injury induced by Ang II. Our findings revealed that miR-134-5p was a novel regulator in vascular remodeling and pathological progress of TAD via targeting STAT5B/ITGB1 expression. Targeting miR-134-5p or its downstream molecules in VSMCs might develop new avenues in clinical treatment of TAD.

A functional variant of SMAD4 enhances macrophage recruitment and inflammatory response via TGF-ß signal activation in Thoracic aortic aneurysm and dissection.

Thoracic aortic aneurysm and dissection (TAAD) is the most fatal macro vascular disease. The mortality of 48h after diagnosis of dissection is up to approximately 50-68%. However, the genetic factors and potential mechanism underlying sporadic TAAD remain largely unknown. Our previous study suggested rs12455792 variant of SMAD4 gene significantly contributed to the increased risk and might participated the pathological progression of TAAD. This investigation aims to test (1) the associations between rs12455792 and MØ recruitment, inflammatory response in aggressiveness of TAAD, and (2) the molecular mechanism accounting for their effects. In TGF-ß signaling molecular detection, rs12455792 C>T variant activated the canonical and non-canonical TGF-ß mediators. It also increased the secretion of chemotactic factors of HASMCs. To confirm the impact of this change, we detected MØ recruitment and infiltration in HASMCs and aortic tissues of TAAD patients. We found that MØ recruitment in cells and tissues with rs12455792 variant genotypes was increased than that in wild type groups. Moreover, rs12455792 variant increased M1 type inflammatory response, which might contribute much to TAAD progression. To mimic the SMAD4 suppression effect of rs12455792 in vivo, we constructed the SMAD4 KD mouse. After induction with Ang II for 4w, the thoracic aorta dilatation and vascular remodeling were more serious than that of wild type group. In conclusion, rs12455792 increased MØ recruitment, M1 type inflammatory response via activated TGF-ß signaling, and further promoted vascular remodeling and pathological progress of TAAD.

A Functional Variant of SMAD4 Enhances Thoracic Aortic Aneurysm and Dissection Risk through Promoting Smooth Muscle Cell Apoptosis and Proteoglycan Degradation.

Recent studies indicate important roles for SMAD4 in SMCs proliferation, extracellular matrix maintenance, and blood vessel remodeling. However, the genetic effects of SMAD4 in the pathogenesis of thoracic aortic aneurysm and dissection (TAAD) are still largely unknown. Here we identified a functional variant of SMAD4 which might be involved in the pathological progression of TAAD. Five tagging SNPs of SMAD4 were genotyped in 202 TAAD cases and 400 controls using MALDI-TOF. rs12455792 CT or TT variant genotypes was associated with an significantly elevated TAAD risk (adjusted OR=1.58, 95%CI=1.09-2.30) under a dominant genetic model. It was located in the 5'UTR and predicted to influence transcription activity and RNA folding of SMAD4. In luciferase reporter assay, rs12455792 T allele markedly decreased luciferase activities. Accordingly, SMAD4 expression in tissues was lower in patients with CT or TT genotypes, compared with CC. Movat's pentachrome showed that rs12455792 T allele enhanced SMCs loss and fibers accumulation. With angiotensin II induction, rate of Apoptotic SMCs was significantly higher while SMAD4 silenced. Moreover, rs12455792 T allele also increased Versican degradation via ADAMTS-4. In conclusion, this variant might promote SMCs apoptosis and proteoglycans degradation, and further facilitate the progress of TAAD. Our findings identified rs12455792 as a predictor for progression of vascular media pathological changes related thoracic aortic disorders.

AKT-modified autologous intracoronary mesenchymal stem cells prevent remodeling and repair in swine infarcted myocardium.

BACKGROUND: Transplantation of adult bone marrow-derived mesenchymal stem cells (MSCs) has been proposed as a strategy for cardiac repair following myocardial damage. However cell transplantation strategies to replace lost myocardium are limited by the inability to deliver large numbers of cells that resist peritransplantation graft cell death. Accordingly, we set out to isolate and expand adult swine bone marrow-derived MSCs, and to engineer these cells to overexpress AKT1 (protein kinase B), to test the hypothesis that AKT1-engineered MSCs are more resistant to apoptosis and can enhance cardiac repair after transplantation into the ischemic swine heart. METHODS: The CDS (regulation domain of AKT1) AKT1-cDNA fragment was amplified, and MSCs were transfected following synthesis with a pCDH1-AKT1 shuttling plasmid. Western blotting analysis and real-time reverse transcription-polymerase chain reaction (RT-PCR) was performed. Myocardial infarction (MI) models were constructed in Meishan pigs, and cardiac function was evaluated by magnetic resonance imaging (MRI) measurements and echocardiography 4 weeks later. All pigs were assigned to four groups: control (A), DMEM (B), MSC (C), and AKT-transfected (D). MSCs were transfected with the AKT1 gene, and autologous BrdU-labeled stem cells (1 x 10(7)/5 ml) were injected into left anterior descending coronary atery (LAD) of the infarct heart in groups C and D. In group B, DMEM was injected using the same approach. In group A, there was no injection following LAD occlusion. After 4 weeks, cardiac function and regional perfusion measurements were repeated by MRI and echocardiography, and histological characteristics of the hearts were assessed. Connecxin-43 (CX-43), BrdU, and von Willebrand factor (VWF) immunoreactivity was tested using enzyme linked immunosorbent assay (ELISA). Vascular endothelial growth factor (VEGF), transforming growth factor-beta1 (TGF-beta1) were analyzed at the same time. RESULTS: AKT1-cDNA was cloned into pCDH1-MCS1-EF1-copGFP and the sequence was confirmed. AKT mRNA expression was detected at 24 hours after transfection. AKT1 expression in MSCs remained strong after 2 weeks, according to real-time RT-PCR and Western blotting. Prior to cell implantation, end-diastolic left ventricular dimension (EDLVd) increased and stroke volume (SV) decreased in the MI hearts. MRI scans revealed significantly improved cardiac function following implantation, and implanted MSCs prevented thinning and expanding in the infarct region, as well as improved contraction and increased perfusion in all groups compared to control hearts. The left ventricular chamber size was smaller in cell-transplanted hearts than in control hearts. Moreover, group D exhibited significant improvement. The expression of CX-43, BrdU, and VWF could be found in the immunohistochemical pathological sections of group C and group D. The level of VEGF reached a high level 1 week after implanting the MSCs, but the level of TGF-beta1 decreased gradually. CONCLUSIONS: The AKT1-expressing lentiviral vector resulted in stable over-expression of AKT1 in MSCs. MSC engraftment in host myocardium improved cardiac function by attenuating contractile dysfunction and pathological thinning of the infracted left ventricular wall, which likely resulted from myocardial regeneration and angiogenesis.