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Cellular cardiomyoplasty has been limited by poor graft retention after cell transplantation. To ensure good retention of the engrafted cells, a microfluidic device was used to fabricate spherical porous beads of poly(D,L-lactic-co-glycolic acid) as a platform for cell delivery. The beads thus obtained had a relatively uniform size, a highly porous structure, and a favorably interconnected interior architecture, to facilitate the transportation of oxygen and nutrients. These porous beads were loaded with human amniotic fluid stem cells (hAFSCs) to generate cellularized microscaffolds. Live/dead assay demonstrated that most of the cells in the porous constructs were viable. The hAFSCs that were grown in beads formed a complex three-dimensional organization with well-preserved extracellular matrices (ECM) according to their porous structure. Retention of the administered beads was clearly identified at the site of engraftment following an experimentally induced myocardial infarction in a rat model. The results of echocardiography, magnetic resonance imaging, and histological analyses suggest that the transplantation of hAFSC beads into an infarcted heart could effectively maintain its gross morphology, prevent successive ventricular expansion, and thereby improve the post-infarcted cardiac function. Immunofluorescent staining revealed that the microenvironment that was provided by the infarcted myocardium might offer cues for the induction of the engrafted hAFSCs into angiogenic and cardiomyogenic lineages. Our results demonstrate that the cellularized beads with endogenously secreted ECM were of sufficient physical size to be entrapped in the interstitial tissues following transplantation, thereby benefiting the infarcted heart., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Direct intramyocardial injection of the desired cell types in a dissociated form is a common route of cell transplantation for repair of damaged myocardium. However, following injection of dissociated cells, a massive loss of transplanted cells has been reported. In this study, human amniotic fluid stem cells (hAFSCs) were used as the cell source for the fabrication of cell sheet fragments, using a thermo-responsive methylcellulose hydrogel system. The fabricated hAFSC sheet fragments preserved the endogenous extracellular matrices (ECM) and retained their cell phenotype. Test samples were xenogenically transplanted into the peri-ischemic area of an immune-suppressed rat model at 1 week after myocardial infarction (MI) induction. There were four treatment groups (n>=10): sham; saline; dissociated hAFSCs; and hAFSC sheet fragments. The results obtained in the echocardiography revealed that the group treated with hAFSC sheet fragments had a superior heart function to those treated with saline or dissociated hAFSCs. Due to their inherent ECM, hAFSC sheet fragments had a better ability of cell retention and proliferation than dissociated hAFSCs upon transplantation to the host myocardium. Additionally, transplantation of hAFSC sheet fragments stimulated a significant increase in vascular density, consequently contributing towards improved wall thickness and a reduction in the infarct size, when compared with dissociated hAFSCs. Our histological findings and qPCR analyses suggest that the transplanted hAFSCs can be differentiated into cardiomyocyte-like cells and cells of endothelial lineages and modulate expression of multiple angiogenic cytokines and cardiac protective factor with the potential to promote neo-vascularization, which evidently contributed to the improvement of ventricular function., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)

Human amniotic fluid stem cells (hAFSCs) derived from second-trimester amniocentesis were evaluated for the therapeutic potential of cardiac repair. Whether hAFSCs can be differentiated into cardiomyogenic cells and toward the maturation of endothelial cell lineage was investigated in vitro using mimicking differentiation milieu. Employing an immune-suppressed rat model with experimental myocardial infarction, an intramyocardial injection was conducted with a needle directly into the peri-infarct areas. There were three treatment groups: sham, saline, and hAFSCs (n > or = 10). When cultured with rat neonatal cardiomyocytes or in endothelial growth medium-2 enriched with vascular endothelial growth factor, hAFSCs were differentiated into cardiomyocyte-like cells and cells of endothelial lineage, respectively. After 4 weeks, hAFSC-treated animals showed a preservation of the infarcted thickness, an attenuation of left ventricle remodeling, a higher vascular density, and thus an improvement in cardiac function, when compared with the saline injection group. Survival and proliferation of the transplanted hAFSCs were revealed by immunohistochemical staining. Expressions of the cardiac-specific markers such as Nkx2.5, alpha-actinin, and cardiac Troponin T were observed in the transplanted hAFSCs. Additionally, Cx43 was clearly expressed at the borders of the transplanted/transplanted and host/transplanted cells, an indication of enhancement of cell connection. The results demonstrated that hAFSCs induce angiogenesis, have cardiomyogenic potential, and may be used as a new cell source for cellular cardiomyoplasty.

Abstract: Growing three-dimensional scaffolds that contain more than a few layers of seeded cells is crucial for the creation of thick and viable cardiac tissues. To achieve this goal, a bioengineered cardiac patch (the MSC patch) composed of a sliced porous biological scaffold inserted with multilayered mesenchymal stem cells (MSCs) was developed for myocardial repair in a syngeneic rat model. After culture, sliced layers of the scaffold were stuck together and seeded MSCs were redistributed throughout the scaffold. Immunofluorescence analyses indicated that cells were viable and tightly adhered to a robust fibronectin meshwork within the scaffold. Results of echocardiography and heart catheterization revealed that the MSC-patch group had a superior heart function to the infarct group. Cells together with neo-muscle fibers and neo-microvessels were clearly observed in the entire MSC patch to fill its original pores, indicating that the implanted patch became well integrated into the host. The thickness of the retrieved MSC patch increased significantly as compared to that before implantation. When compared with the infarct group, expressions of angiogenic cytokines (bFGF, vWF and PDGF-B) and cardioprotective factors (IGF-1 and HGF) were significantly increased in the MSC-patch group. The aforementioned results indicated that transplantation of the MSC patch could restore the dilated LV and preserve cardiac functions after infarction. [Copyright &y& Elsevier]

Abstract: A patch is often mandatory to repair myocardial defects; however, currently available patches lack the possibility of regeneration. To overcome this limitation, a porous acellular bovine pericardium seeded with BrdU-labeled mesenchymal stem cells (MSCs) was prepared (the MSC patch) to repair a surgically created myocardial defect in the right ventricle of a syngeneic rat model. The bovine pericardium before cell extraction was used as a control (the Control patch). The implanted samples were retrieved at 4- and 12-week postoperatively ( per group at each time point). At retrieval, no aneurysmal dilation of the implanted patches was seen for both studied groups. No apparent tissue adhesion was observed for the MSC patch throughout the entire course of the study, while for the Control patch, two out of the five studied animals at 12-week postoperatively had a filmy adhesion to the chest wall. On the inner (endocardial) surface, intimal thickening was observed for both studied groups; however, no thrombus formation was found. Intact layers of endothelial and mesothelial cells were identified on the inner and outer (epicardial) surfaces of the MSC patch. Smooth muscle cells together with neo-muscle fibers, neo-glycosaminoglycans and neo-capillaries were observed within the pores of the MSC patch. Some cardiomyocytes, which stained positively for BrdU and α-sacromeric actin, were observed in the MSC patch, indicating that the implanted MSCs can engraft and differentiate into cardiomyocytes. Additionally, a normality of the local electrograms on the epicardial surface of the MSC patch was observed. In contrast, no apparent tissue regeneration was observed for the Control patch throughout the entire course of the study, while only abnormal electrogram signals were seen on its epicardial surface. In conclusion, the MSC patch may preserve the structure of the ventricular wall while providing the potential for myocardial tissue regeneration. [Copyright &y& Elsevier]