Bachelor of Science, University of California San Diego (2007)
Doctor of Philosophy, University of California Davis (2013)
Ngan Huang, Postdoctoral Faculty Sponsor
It is generally agreed that engineered cardiovascular tissues require cellular interactions with the local milieu. Within the microenvironment, the extracellular matrix (ECM) is an important support structure that provides dynamic signaling cues in part through its chemical, physical, and mechanical properties. In response to ECM factors, cells activate biochemical and mechanotransduction pathways that modulate their survival, growth, migration, differentiation, and function. This Review describes the role of ECM chemical composition, spatial patterning, and mechanical stimulation in the specification of cardiovascular lineages, with a focus on stem cell differentiation, direct transdifferentiation, and endothelial-to-mesenchymal transition. The translational application of ECMs will be discussed in the context of cardiovascular tissue engineering and regenerative medicine.
View details for DOI 10.1002/adhm.201300620
View details for PubMedID 24443420
Initial steps in establishing an optimal strategy for functional bioengineered tissues is generation of three-dimensional constructs containing cells with the appropriate organization and phenotype. To effectively utilize rhesus monkey decellularized kidney scaffolds, these studies evaluated two key parameters: (1) residual scaffold components after decellularization including proteomics analysis, and (2) the use of undifferentiated human embryonic stem cells (hESCs) for recellularization in order to explore cellular differentiation in a tissue-specific manner. Sections of kidney and lung were selected for a comparative evaluation because of their similar pattern of organogenesis. Proteomics analysis revealed the presence of growth factors and antimicrobial proteins as well as stress proteins and complement components. Immunohistochemistry of recellularized kidney scaffolds showed the generation of Cytokeratin+ epithelial tubule phenotypes throughout the scaffold that demonstrated a statistically significant increase in expression of kidney-associated genes compared to baseline hESC gene expression. Recellularization of lung scaffolds showed that cells lined the alveolar spaces and demonstrated statistically significant upregulation of key lung-associated genes. However, overall expression of kidney and lung-associated markers was not statistically different when the kidney and lung recellularized scaffolds were compared. These results suggest that decellularized scaffolds have an intrinsic spatial ability to influence hESC differentiation by physically shaping cells into tissue-appropriate structures and phenotypes, and that additional approaches may be needed to ensure consistent recellularization throughout the matrix.
View details for DOI 10.1371/journal.pone.0064134
View details for PubMedID 23717553
New therapies for severely damaged kidneys are needed due to limited regenerative capacity and organ donor shortages. The goal of this study was to repopulate decellularized kidney sections in vitro and to determine the impact of donor age on recellularization. This was addressed by generating decellularized kidney scaffolds from fetal, juvenile, and adult rhesus monkey kidney sections using a procedure that removes cellular components while preserving the structural and functional properties of the native extracellular matrix (ECM). Kidney scaffolds were recellularized using explants from different age groups (fetal, juvenile, adult) and fetal renal cell fractions. Results showed vimentin+ cytokeratin+ calbindin+ cell infiltration and organization around the scaffold ECM. The extent of cellular repopulation was greatest with scaffolds from the youngest donors, and with seeding of mixed fetal renal aggregates that formed tubular structures within the kidney scaffolds. These findings suggest that decellularized kidney sections from different age groups can be effectively repopulated with donor cells and the age of the donor is a critical factor in repopulation efficiency.
View details for DOI 10.1089/ten.tea.2010.0714
View details for Web of Science ID 000298077900001
View details for PubMedID 21902603
The goal of this study was the production of a decellularized kidney scaffold with structural, mechanical, and physiological properties necessary for engineering basic renal structures in vitro. Fetal, infant, juvenile, and adult rhesus monkey kidney sections were treated with either 1% (v/v) sodium dodecyl sulfate or Triton X-100 followed by quantitative and qualitative analysis. Comparison of decellularization agents and incubation temperatures demonstrated sodium dodecyl sulfate at 4 degrees C to be most effective in preserving the native architecture. Hematoxylin and eosin staining confirmed the removal of cellular material, and immunohistochemistry demonstrated preservation of native expression patterns of extracellular matrix proteins, including heparan sulfate proteoglycan, fibronectin, collagen types I and IV, and laminin. Biomechanical testing revealed a decrease in the compressive modulus of decellularized compared to fresh kidneys. Layering of fetal kidney explants on age-matched decellularized kidney scaffolds demonstrated the capacity of the scaffold to support Pax2+/vimentin+ cell attachment and migration to recellularize the scaffold. These findings demonstrate that decellularized kidney sections retain critical structural and functional properties necessary for use as a three-dimensional scaffold and promote cellular repopulation. Further, this study provides the initial steps in developing new regenerative medicine strategies for renal tissue engineering and repair.
View details for DOI 10.1089/ten.tea.2009.0602
View details for Web of Science ID 000279455500010
View details for PubMedID 20156112