Browsing by Author "Balaoing, Liezl R."

Now showing 1 - 3 of 3
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    3-Dimensional spatially organized PEG-based hydrogels for an aortic valve co-culture model
    (Elsevier, 2015) Puperi, Daniel S.; Balaoing, Liezl R.; O'Connell, Ronan W.; West, Jennifer L.; Grande-Allen, K. Jane; Bioengineering
    Physiologically relevant inﾠvitro models are needed to study disease progression and to develop and screen potential therapeutic interventions for disease. Heart valve disease, in particular, has no early intervention or non-invasive treatment because there is a lack of understanding the cellular mechanisms which lead to disease. Here, we establish a novel, customizable synthetic hydrogel platform that can be used to study cell-cell interactions and the factors which contribute to valve disease. Spatially localized cell adhesive ligands bound in the scaffold promote cell growth and organization of valve interstitial cells and valve endothelial cells in 3D co-culture. Both cell types maintained phenotypes, homeostatic functions, and produced zonally localized extracellular matrix. This model extends the capabilities of inﾠvitro research by providing a platform to perform direct contact co-culture with cells in their physiologically relevant spatial arrangement.
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    Hyaluronan turnover and hypoxic brown adipocytic differentiation are co-localized with ossification in calcified human aortic valves
    (Elsevier, 2012) Stephens, Elizabeth H.; Saltarrelli, Jerome G. Jr.; Balaoing, Liezl R.; Baggett, L. Scott; Nandi, Indrajit; Anderson, Kristin M.; Morrisett, Joel D.; Reardon, Michael J.; Simpson, Melanie A.; Weigel, Paul H.; Olmsted-Davis, Elizabeth A.; Davis, Alan R.; Grande-Allen, K. Jane; Bioengineering; Statistics
    The calcification process in aortic stenosis has garnered considerable interest but only limited investigation into selected signaling pathways. This study investigated mechanisms related to hypoxia, hyaluronan homeostasis, brown adipocytic differentiation, and ossification within calcified valves. Surgically explanted calcified aortic valves (nﾠ=ﾠ14) were immunostained for markers relevant to these mechanisms and evaluated in the center (NodCtr) and edge (NodEdge) of the calcified nodule (NodCtr), tissue directly surrounding nodule (NodSurr); center and tissue surrounding small ﾓprenodulesﾔ (PreNod, PreNodSurr); and normal fibrosa layer (CollFibr). Pearson correlations were determined between staining intensities of markers within regions. Ossification markers primarily localized to NodCtr and NodEdge, along with markers related to hyaluronan turnover and hypoxia. Markers of brown adipocytic differentiation were frequently co-localized with markers of hypoxia. In NodCtr and NodSurr, brown fat and ossification markers correlated with hyaluronidase-1, whereas these markers, as well as hypoxia, correlated with hyaluronan synthases in NodEdge. The protein product of tumor necrosis factor-? stimulated gene-6 strongly correlated with ossification markers and hyaluronidase in the regions surrounding the nodules (NodSurr, PreNodSurr). In conclusion, this study suggests roles for hyaluronan homeostasis and the promotion of hypoxia by cells demonstrating brown fat markers in calcific aortic valve disease.
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    Identifying Behavioral Phenotypes and Heterogeneity in Heart Valve Surface Endothelium
    (Karger, 2016) Blancas, Alicia A.; Balaoing, Liezl R.; Acosta, Francisca M.; Grande-Allen, K. Jane; Bioengineering
    Heart valvular endothelial cells (VECs) are distinct from vascular endothelial cells (ECs), but have an uncertain context within the spectrum of known endothelial phenotypes, including lymphatic ECs (LECs). Profiling the phenotypes of the heart valve surface VECs would facilitate identification of a proper seeding population for tissue-engineered valves, as well as elucidate mechanisms of valvular disease. Porcine VECs and porcine aortic ECs (AECs) were isolated from pig hearts and characterized to assess known EC and LEC markers. A transwell migration assay determined their propensity to migrate toward vascular endothelial growth factor, an angiogenic stimulus, over 24 h. Compared to AECs, Flt-1 was expressed on almost double the percentage of VECs, measured as 74 versus 38%. The expression of angiogenic EC markers CXCR4 and DLL4 was >90% on AECs, whereas VECs showed only 35% CXCR4+ and 47% DLL4+. AECs demonstrated greater migration (71.5 ± 11.0 cells per image field) than the VECs with 30.0 ± 15.3 cells per image field (p = 0.032). In total, 30% of VECs were positive for LYVE1+/Prox1+, while these markers were absent in AECs. In conclusion, the population of cells on the surface of heart valves is heterogeneous, consisting largely of nonangiogenic VECs and a subset of LECs. Previous studies have indicated the presence of LECs within the interior of the valves; however, this is the first study to demonstrate their presence on the surface. Identification of this unique endothelial mixture is a step forward in the development of engineered valve replacements as a uniform EC seeding population may not be the best option to maximize transplant success.