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ABSTRACT: Based on a porcine model with surgically created myocardial infarction (MI) as a pre-clinical scheme, this study investigates the clinical translation of cell sheet fragments of autologous mesenchymal stem cells (MSCs) for cellular cardiomyoplasty. MSC sheet fragments retaining endogenous extracellular matrices are fabricated using a thermo-responsive methylcellulose hydrogel system. Echocardiographic observations indicate that transplantation of MSC sheet fragments in infarcted hearts can markedly attenuate the adverse ventricular dilation and preserve the cardiac function post MI, which is in contrast to the controlled groups receiving saline or dissociated MSCs. Additionally, histological analyses suggest that administering MSC sheet fragments significantly prevents the scar expansion and left ventricle remodeling after MI. Immunohistochemistry results demonstrate that the engrafted MSCs can differentiate into endothelial cells and smooth muscle cells, implying that angiogenesis and the subsequent regional perfusion improvement is a promising mechanism for ameliorating post-infarcted cardiac function. However, according to the data recorded by an implantable loop recorder, the transplanted MSCs may provoke arrhythmia. Nevertheless, the proposed approach may potentially lead to the eventual translation of MSC-based therapy into practical and effective clinical treatments.
Biomaterials 03/2013; · 7.40 Impact Factor
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ABSTRACT: Trypanosoma (subgenus Megatrypanum) theileri was first identified over one hundred years ago, and is a widespread parasite in cattle. Its life cycle within the mammalian host has rarely been reported. Whether there is an intracellular stage in tissues is unknown and such a stage has not been demonstrated experimentally. Intriguingly, using Giemsa staining with light microscopy and transmission electron microscopy examination, we found that the parasite was able not only to attach to cells but also to invade several phagocytic and non-phagocytic mammalian cells. Based on these findings, we conducted further investigations using a special antibody in immunofluorescence confocal images. Moreover, we examined a series of possible events of cell invasion in T. theileri. The results revealed that GM1, a marker of membrane rafts, was implicated in the mechanism of entry by this parasite. After incubation with tissue culture trypomastigotes, the gelatinolytic activity was significantly increased and accumulated at the attachment sites. Using ultrastructural localization detection by CytoTracker live imaging and confocal immunofluorescence microscopy, we found that lysosome fusion and the autophagy pathway were engaged in invaginating processes. T. theileri amastigotes also invaded cells and were enclosed by the lysosomes. Furthermore, tissue-cultured trypomastigotes were found to be capable of triggering intracellular free Ca(2+) transients and TGF-β-signaling. Our findings that intracellular amastigote stages exist in mammalian cells infected with T. theileri and that the invasion processes involved various host cell components and cell signalings were extremely surprising and warrant further investigation.
Veterinary Parasitology 09/2012; · 2.58 Impact Factor
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ABSTRACT: This study aimed to investigate the relationship between oxidized regenerated cellulose (ORC) and mucosa healing in an experimental animal model.
Fifteen adult Sprague-Dawley rats were randomly divided into three groups that underwent different wound treatments. In Group 1, no pharyngeal wound was created. In Group 2, the pharyngeal wound was sutured with Prolene only. In Group 3, the pharyngeal wound was sutured with Prolene, and covered with one layer of ORC before closure of the skin wound. The animals were euthanized either 5 or 10 days after operation, and wound conditions were inspected and recorded. Specimens including sections of larynx and pharynx/upper esophagus were taken for microscopic and molecular biological examination.
The pharyngotomy/esophagotomy wounds achieved good healing outcomes 10 days after operation. Wounds treated with ORC had significantly diminished inflammatory cell infiltration in microscopic examination when compared with that of those without ORC 5 days after operation. The matrix metalloproteinases (MMP) expression level was higher in wounds of Group 2 and Group 3, when compared with that of group 1. In addition, the MMP expression level was lower in the ORC-treated wounds when compared with that of those without ORC. There was no significant difference in fibroblast proliferation, collagen deposition, endothelin-1, alpha-smooth muscle actin, and transforming growth factor beta 1 expression level between wounds treated with ORC and those without ORC.
Reduced inflammatory response and decreased MMP expression level was observed in ORC-treated wounds. Whether ORC facilitates mucosa healing requires further investigation.
Journal of the Chinese Medical Association 04/2012; 75(4):176-82. · 0.79 Impact Factor
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ABSTRACT: Rapid induction and creation of functional vascular networks is essential for the success of treating ischemic tissues. The formation of mature and functional vascular networks requires the cooperation of endothelial cells (ECs) and perivascular cells. In the study, we used a thermo-responsive hydrogel system to fabricate core-shell cell bodies composed of cord-blood mesenchymal stem cells (cbMSCs) and human umbilical vascular ECs (HUVECs) for functional vasculogenesis. When seeded on Matrigel, the shelled HUVECs attempted to interact and communicate vigorously with the cored cbMSCs initially. Subsequently, HUVECs migrated out and formed tubular structures; cbMSCs were observed to coalesce around the HUVEC-derived tubes. With time progressing, the tubular networks continued to expand without regression, indicating that cbMSCs might function as perivascular cells to stabilize the nascent networks. In the in vivo study, cbMSC/HUVEC bodies were embedded in Matrigel and implanted subcutaneously in nude mice. At day 7, visible blood-filled vessels were clearly identified within the implant containing cbMSC/HUVEC bodies, indicating that the formed vessels anastomosed with the host vasculature. The cored cbMSCs were stained positive for smooth muscle actin, suggesting that they underwent smooth muscle differentiation and formed microvessels with the shelled HUVECs, as the role of perivascular cells. These data confirm that the formation of mature vessels requires heterotypic cooperation of HUVECs and MSCs. This study provides a new strategy for therapeutic vasculogenesis, by showing the feasibility of using cbMSC/HUVEC bodies to create functional vascular networks.
Biomaterials 08/2011; 32(33):8446-55. · 7.40 Impact Factor
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ABSTRACT: Individual activation of nicotinic acetylcholine receptor (nAChR) or nitric oxide (NO) synthase in the dorsal facial area (DFA) increases blood flow of common carotid artery (CCA) supplying intra- and extra-cranial tissues. We investigated whether the activation of nAChR initiated the activation of NO synthase and guanylyl cyclase to increase CCA blood flow in anesthetized cats. Microinjections of nicotine (a non-selective nAChR agonist), or choline (a selective α7-nAChR agonist) in the DFA produced increases in CCA blood flow ipsilaterally. These increases were significantly reduced by pretreatment with NG-nitro-arginine methyl ester (l-NAME, a non-specific NO synthase inhibitor), 7-nitroindazole (7-NI, a relatively selective neuronal NO synthase inhibitor) or methylene blue (MB, a guanylyl cyclase inhibitor) but not by that with N5-(1-iminoethyl)-l-ornithine (l-NIO, a potent endothelial NO synthase inhibitor). Control microinjection with d-NAME (an isomer of l-NAME), artificial cerebrospinal fluid or DMSO (a solvent for 7-NI) did not affect resting CCA blood flow, nor did they affect nicotine- or choline-induced response. In conclusion, activation of nAChR, at least α7-nAChR, led to the activation of neuronal NO synthase and guanylyl cyclase in the DFA, which induced an increase in CCA blood flow.
Neuroscience Letters 12/2010; 486(3):122-6. · 2.11 Impact Factor
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I-Chen Tsai,
Jin-Long Huang,
Kwo-Chang Ueng, Yi-Wen Hung,
Chin-Fang Hung,
Wan-Chun Liao,
Ho-Yi Lei,
Min-Chi Chen,
Wei-Lin Tsai,
Shih-Ann Chen,
Clayton Chi-Chang Chen,
Yun-Ching Fu,
Chih-Tai Ting
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ABSTRACT: This study used multi-detector row CT (MDCT) to evaluate the regional geometric parameters of left ventricle (LV) in patients and dogs after right ventricular apical (RVA) pacing. First, we measured and compared the global and regional wall motion parameters derived from MDCT images between three patients post RVA pacing and seven age-matched healthy subjects. The LV ejection fraction (LVEF), LV end-diastolic volume and LV end-systolic volume were measured. We also measured the regional wall thickness, wall thickening and regional wall motion in 12 different segments of the LV. Second, we performed MDCT scan on five dogs as the study group (pacing wire + RVA pacing, 2 months) and four dogs as the sham control group (pacing wire, 2 months). The global and regional geometric parameters were compared within both human and canine groups. Compared with normal subjects, patients post RVA pacing had low LVEF (60.4 ± 10.5 vs. 33.2 ± 17.6, P = 0.014), impaired regional wall thickening and regional wall motion, particularly in segments near the pacing lead. Some segments near the pacing lead were showing dyskinesia after pacing. These findings were successfully reproduced in the canine model. We found that RVA pacing can result in impaired regional wall thickening and regional wall motion, particularly in segments near the pacing lead.
The international journal of cardiovascular imaging 12/2010; 26(Suppl 2):223-35. · 2.15 Impact Factor
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ABSTRACT: Growing three-dimensional (3D) scaffolds that contain more than a few layers of seeded cells in vitro is crucial for the creation of thick and viable cardiac tissues in vivo. Embryonic stem cells (ESCs) have been used as an alternative cell source for cardiac repair; however, dissociated ESCs show poor viability in the scaffold and do not form the embryoid body (EB)-like structures. In this study, a strategy intended for cultivating EB-derived cells (EBDCs) uniformly in a porous 3D tissue scaffold was developed. This strategy employed techniques of formation of spherically symmetric EBs in a thermo-responsive hydrogel system, production of cell sheets of EBDCs in a similar hydrogel system coated with collagen and fabrication of sliced porous tissue scaffolds. The prepared EBs were collected and plated evenly in the cell-sheet culture system. After 8 days in culture, a continuous sheet of EBDCs with cell beating was obtained; our qPCR and flow cytometric analyses showed that the collagen-coated on the cell-sheet culture system can significantly enhance the population of cardiac-lineage cells. The produced EBDC sheets were then sandwiched into the sliced porous tissue scaffold. After reculture, the seeded EBDCs were redistributed uniformly throughout the scaffold, with a significant increase in mechanical strength. Cardiac-specific myosin heavy chain and alpha-actinin were expressed for some cells grown in the scaffold, while connexin 43 was clearly expressed at the cell borders. Additional studies such as employing purification techniques to enrich the population of cardiomyocytes are needed to further improve the developed tissue constructs as a bioengineered cardiac patch.
Biomaterials 08/2010; 31(24):6218-27. · 7.40 Impact Factor
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ABSTRACT: Drug-eluting stents have emerged as a predominant percutaneous strategy in patients with coronary artery disease. However, hypersensitivity reactions caused by their nonerodable polymer coatings and bare-metal stents may result in serious clinical sequelae. In this report, a new biodegradable sirolimus-eluting stent, made from chitosan-based strips fixed by an epoxy compound, coated with a hydrophobic heparin was developed. Due to the covalent crosslinks formed in the stent matrix, the fabricated stent had a shape-memory property to memorize its permanent shape. The shape-memory ability and mechanical strength of the stent could be enhanced by increasing its degree of crosslinking. The cytocompatibility of the stent was demonstrated in vitro. The heparin coating on the stent effectively reduced platelet adhesion; additionally, it acted as a diffusion barrier and led to a nearly linear sustained-release profile of sirolimus. Cell-cycle analysis demonstrated that the released sirolimus could inhibit smooth muscle cell proliferation by inducing cell-cycle arrest in G(1) phase. When compared to the unloaded stent, neointimal formation was significantly suppressed after implantation of the sirolimus-eluting stent in rabbit infrarenal abdominal aortas. These findings suggested that the developed sirolimus-eluting polymeric stent can be a potential alternative for treatment of atherosclerosis.
Biomaterials 11/2008; 30(1):79-88. · 7.40 Impact Factor
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ABSTRACT: Intravenous norepinephrine (NE) at a dose of 1-6 microg/kg/minute can induce increased extracellular matrix (ECM) and hypertrophic cardiomyopathy. This study aimed to investigate the effects of a higher dose of NE on cardiac remodeling.
After intraperitoneal urethane-chloralose anesthesia, 7 cats (3.03 +/- 0.58 kg) received intravenous infusion of NE 30 microg/kg/minute for 3 hours. Aortic blood pressure and heart rate (HR) were measured by polygraphy at 0, 5, 15, 30, 60, 90, 120, and 180 minutes. Left ventricular size and ejection fraction (EF) were measured by M-mode echocardiography before and after NE administration. Histopathology was performed by hematoxylin-eosin, silver impregnation, and Sirius red staining. Activity of matrix metalloproteinases (MMP) in the left ventricle was measured by zymography.
Mean blood pressure (mmHg) increased from 139 +/- 20 to 198 +/- 19, 187 +/- 23, and 166 +/- 16 at 15, 30, and 60 minutes, respectively, during NE infusion. HR (beats/minute) decreased from 214 +/- 10 to 158 +/- 28 at 15 minutes and then recovered gradually. The left ventricles showed significant dilatation (end-diastolic diameter: from 1.20 +/- 0.18 to 1.58 +/- 0.23cm, p=0.003; end-systolic diameter: from 0.62 +/- 0.23 to 1.35 +/- 0.29cm, p=0.002) and hypokinesia (EF: from 86.2 +/- 5.2 to 33.1 +/- 16.5%, p < 0.001). Histopathology revealed that left ventricular myocytes were elongated, wavy, and fragmented, while collagen fibers were overstretched, straightened, and disrupted. MMP-9 activity was significantly elevated (p = 0.003 vs. control), while MMP-2 activity was unchanged.
High-dose NE increases MMP-9 activity and causes ECM disruption, left ventricular dilatation and dysfunction.
Journal of the Chinese Medical Association 08/2006; 69(8):343-50. · 0.79 Impact Factor
