Cellular Bioengineering (Liver, Skin), Cell-Interactive Biomaterials, Micro/Nanosystems Bioengineering
Professor Moghe's current research activities are organized into three major thrust areas.
(1) Lipoprotein Retentive Nanoscale Substrates for Treatment of Atherosclerosis
Cardiovascular disease takes a staggering toll of casualties among adult Americans each year. Two of the significant vascular pathologies related to the abnormal accumulation of lipids are atherosclerosis and macrovascular disease, which claims a million lives each year globally. Much research has been directed at the molecular design of drugs to alleviate the disorders of lipid metabolism. However, such drugs fail to comprehensively treat lipoprotein transport and retention dynamics. particularly at peripheral vascular sites. Thus, a comprehensive approach to treating lipid-related vascular disease could involve use of molecules regulating lipid metabolism as well as molecules that are suitably lipoprotein-philic and serve as multifunctional carriers for processing lipoproteins in transit. Ultimately, such carriers could be engineered to (a) sequester lipoproteins from macromolecular depots such as proteoglycans that heighten atherogenic tendencies; (b) reduce lipoprotein oxidation (which leads to unregulated uptake of LDL by macrophages, transforming them into foam cells, the precursors to atherosclerosis); and (c) enhance lipoprotein transport and clearance of mildly oxidized lipoproteins (via macrophages, and the liver). However, to engineer such carriers, an understanding of the chemical and geometric determinants of lipoprotein-retentive carrier substrates is necessary. Through active collaborations with Professor Uhrich (Chemistry) and Professor Tomassone (Chemical and Biochemical Engineering), we are currently investigating the chemistry and nanoscale geometry of substrates with maximal LDL retentivity. As a competitive strategy for LDL retention, novel diffusible, nanoscale carriers will be designed, that can present GAG-mimetic chemistry and retain LDL with high affinity.
(2) Biodynamic Ligand Nanointerfaces with Biomaterials For Wound Healing/Tissue Engineering
Migration of epidermal cells such as keratinocytes is critical to efficient re-epithelialization of chronic wounds and bioartificial matrices used in the tissue engineering of skin. We hypothesize that the establishment of a highly biodynamic interface of ligands on polymer substrates can significantly enhance the activation of cell motility. We have recently filed a patent application for such an interface by displaying adhesion ligands (fibronectin and its fragments) at the surface of self-assembled nanoshells of degradable matrix molecules, and presenting it on differentially PEGylated polymeric materials. We expect that cell activation can be systematically promoted through such interfaces via two primary mechanisms: first, at certain PEG levels in the polymer substrate, the ligand-nanocarrier can be actively "remodeled" upon cell attachment; second, by designing the appropriate size of the nanocarrier and the chemistry of the minimally activating ligand fragment, the entire ligand-nanocarrier can be internalized within the cells, thus activating the cells through a parallel endocytic pathway. This study focuses on the study of the trafficking dynamics of ligand nanocarriers through multiphoton microscopy of quantum-dot encapsulated ligand-nanocarriers. The use of quantum dots with different emission wavelengths will allow us to discriminate between the trafficking behavior of different ligand fragments. Finally, we will elucidate the changes in intracellular signaling molecules upon activation through the ligand nanocarriers. The innovative components of this research are its focus on biodynamic nanoscale ligand substrates that can activate cells through enhanced "sampling dynamics" of ligands at the cell-ligand adhesive interface. which has direct relevance to the ultimate development of improved biomimetic materials technology. This project is a result of multidisciplinary collaborations with Profs. Joachim Kohn (Chemistry) and Richard Riman (Ceramics & Materials Eng).
(3) Cytomimetic Materials for Cell Adhesion and Differentiation
The identification of appropriate liver-specific biomolecular signals can greatly enhance the cell-specific signaling elicited by "biomimetic" substrates for applications in cell-based ex vivo bioreactors, hepatic tissue engineering, and studies of pharmacology and toxicology using cell-based devices. Most adhesive matrix ligands, however, generally promote growth of liver cells (hepatocytes) at the expense of hepatocellular differentiation. We are currently exploring approaches to systematically establish a new biopolymeric hepatocyte-supporting interface based on fragments of the cell-cell adhesion molecule, E-cadherin. Cadherins are ubiquitous adhesion molecules that can trigger intracellular signaling necessary for liver-specific differentiated gene expression. However, the cell functional determinants of cadherin microdisplay from polymer substrates are not currently understood. Cadherin-activation of cell differentiation is usually studied in systems with multicellular adhesion. due to which direct cadherin activation in individual cells cannot be decoupled from juxtacrine signaling caused by secondary cell-cell adhesion processes. Therefore, we are investigating the role of cadherin signaling on single-cell systems (using micropatterned ligands), as well as on multicellular systems (using cocultures and hepatocyte aggregates). In our single-cell studies, we utilize advances in microscale lithographic technology to create microstamped anchors for display of variable concentrations of E-cadherin chimeras from "discrete" biopolymeric islands of microscale dimensions, for binding to single hepatocytes. The study has one major objective, to study the effect of cadherin microdisplay on single cell adhesion and intracellular cytoskeletal activity (morphogenesis, and differentiated gene expression and signaling. We seek to identify a microdisplay regimen where cadherin (ligand) binding can cause intracellular cytoskeletal complexation and adhesion strengthening without significant overall cell morphogenesis. Furthermore, the effects of cadherin presentation are examined on upstream signaling of cadherin-activated pathways and downstream gene expression profiling of key transcription factors that may promote liver-specific differentiated functions. The outcomes of single-cell studies can potentially aid: the development of novel single hepatocyte cultures for diagnostic applications (cell-on-a-chip for pharmacology); and design of "cell-mimetic" substrates for cell transplantation, which are function inductive even under conditions of sparse cellularity. Our recent coculture studies of hepatocytes and E-cadherin transfected fibroblasts have shown that the progressive display of E-cadherins at the heterocellular interface can significantly improve hepatocellular function beyond the basal elevation of function due to mixed cultures. We are currently investigating the parameters that can maximize this effect using acellular cadherins displayed from microbeads and micropillars. in an effort to recapitulate the minimal functional determinants in the coculture system.
Funding Sponsors: National Science Foundation, American Heart Association, Johnson & Johnson Discovery Award, Rutgers SROA Award, NIH Biotechnology Training Program, NIH NCRR Grant