RESEARCH
NARRATIVE
Dr.
Moghe's research is focused on three major areas, described further in the
narrative below. (1) Cellular
Bioengineering; (2) Nanobiomaterials and Nanobiotechnology; and (3)
Cell-Biomaterial Interactions.
Selected
publications of Moghe's work appear on-line at: http://www.rci.rutgers.edu/~moghe/Publications.html
Cellular
Bioengineering
Current
and Past Members of Moghe Laboratory:
Dr. Colette Ranucci, Dr. Thomas Brieva, Dr. Anouska Dasgupta, Dr. Eric
Semler, Rebecca Hughey, Nayyereh Rajaei, Perry Lancin, Zubia Naji,
Collaborators: Dr. Fredrick Kauffman (Pharmacology,
Rutgers), Dr. Ronald Hart (Cell Biology, Rutgers), Dr. Surendra Batra (Integra
LifeSciences), Dr. Mehmet Toner (Harvard), Dr. Lionel Larue (Institut Curie, France),
Dr. Malcolm Steinberg (Princeton)
Funding
Sources: NSF, NIH, Johnson & Johnson, Merck, Biocure, Integra LifeSciences
Dr.
Moghe's research in the area of cell and tissue engineering has addressed the
role of matrix, substrate, and growth factor cues on the phenotypic and
differentiation behavior of liver cells, hepatocytes, and embryonic stem
cells. At Rutgers, Dr. Moghe and
his graduate students have reported that the morphogenesis and differentiation
of anchorage-sensitive hepatocytes can be acutely governed by changes in the
substrate microscale topography as well as the nature of adsorbed matrix
ligands. Dr. Moghe's studies
(supported by the NSF CAREER Program) examined how hepatocyte differentiation
can be engineered through the interplay of substrate topography and
matrix/mechanochemical stimulation.
Dr. Moghe's papers with his graduate students and postdocs in Tissue
Engineering,
Biomaterials,
and J. Biomedical Materials Research, have been frequently cited by investigators in
the field. For example, a recent review
in Science (Assender et al., 2002) cites the publication on cooperative effects on cell motility
dynamics of ligand adsorption and material microstructure (Ranucci and Moghe, 2001).
Using
differentially compliant hydrogels, Dr. Moghe reported that increased growth
factor stimulation and growth factor pulsing can be used as a dual strategy to
promote differentiation or cell growth (Semler and Moghe, 2001;
Semler et al., 2000). This pioneering work has been widely cited, ranging from
tissue engineering papers such as Dr. Robert Langer's review in Developmental
Biology (Levenberg and Langer,
2004), Dr. Paul Janmey's review
in J. Appl. Physiology (Georges and Janmey, 2005), all the way to leading cell/molecular biology journal such as
J. Cell Science (Haouzi et al., 2005). Advancing these studies further using a new system of
polyacrylamide substrates functionalized with matrix ligand, fibronectin, Dr.
Moghe and graduate student, Eric Semler, showed using hydrogels of intermediate
compliance that hepatocytes can be made to differentiate with highest
sensitivity when exposed to increased ligand concentration (Semler et al., 2005). This recent
study was cited in a prominent review in Science focussed on cellular
engineering via rigid/compliant substrates by Dr. Dennis Discher and colleagues
at U. Pennsylvania (Discher et al., 2005). Dr. Linda
Griffith of MIT also cites this work in her 2006 Nature Reviews- Molecular
& Cell Biology (Griffith and Swartz, 2006).
In
the area of hepatocellular engineering, Dr. Moghe has pioneered the approach of
incorporation of adhesive and signaling cell-cell adhesion molecule, the
cadherins, for controlled differentiation of hepatocytes. Five prominent publications from his
laboratory have by now documented that (a) cadherin based cell-cell adhesion
between liver cells and other cell types can significantly promote cell
differentiation (Brieva and Moghe, 2001) (b) the mode of cadherin display can engineer the
differentiation-proliferation balance (Brieva and Moghe, 2004) (c) acellular fragments of E-cadherin can used on artificial
substrates to promote hepatocyte differentiation (Semler et al., 2005); and, recently, that (d) E-cadherins can promote embryonic
stem cell differentiation in conjunction with growth factor stimulation (Dasgupta et al., 2005). Current advances
in the Moghe laboratory, using approaches utilizing microfabrication,
immunocytochemistry, and DNA microarray technology, show that E-cadherin
engineered embryonic stem cells can be more effectively primed to mature to
differentiated hepatocyte-like cells when transplanted within liver-like
environments in vitro (Hughey et al., 2006). This is the
first report in the field that probes the maturation potential of ES cells in
the presence of adult hepatocytes.
These studies are expanding the investigation to include several new
questions in the area: (a) Can
cadherin-engineered ES cells be further genetically modified via SiRNA
technology? (b) Can cadherin-based wnt signaling and other growth factor signaling
be used cooperatively to promote the kinetics of ES cell maturation? (c) Can cadherin engineering insights
learned from murine ES cells be applied to human ES cells (being addressed
through a current collaboration between Dr. Moghe, and Drs. Larue of France and
Cellartis, Inc. of Sweden).
Nanobiomaterials
and Nanobiotechnology
Current
and Past Members of Moghe Laboratory: Jane S. Tjia, Ram I. Sharma, Evangelia
Chnari, Nicole Iverson, Nicole Plourde, Dr. Marian Pereira, Dr. Maria Rossi,
Thomas Gentzel, Rebecca Penkala, Eileen Dawson, Jessica Nikitczuk
Collaborators: Dr. Brian Aneskievich (UMDNJ/U.
Connecticut); Dr. Jean Schwarzbauer (Princeton); Dr. Kathryn Uhrich (Rutgers,
Chemistry); Dr. David Talaga (Rutgers, Chemistry); Dr. Gary Nackman (UMDNJ,
Surgery); Dr. Joanna Aizenberg (Lucent Technologies/Bell Labs); Dr. Thomas
Tsakalakos (Rutgers Materials Science & Eng); Dr. Aric Menon (Tech. U,
Denmark)
Funding
Sources: NSF, NIH, Johnson & Johnson, Integra LifeSciences
Two
major federally funded research projects in the Moghe laboratory pursue studies
on the design and elucidation of nanoscale particles for controlled
interactions with cells. These are
discussed below.
Nanoparticles
for Engineered Cell Biodynamics in Cell/Matrix Engineering
Cell
adhesion to the extracellular matrix is followed by a series of cellular
events, such as cell spreading, cell migration or differentiation or
proliferation. Given the
complexity and dynamic nature of cell interactions with the matrix ligands,
biointerfacial/biomaterials scientists and bioengineers are now trying to
recapitulate the biodynamic nature of the cell-ligand interface. Dr. Moghe has made a major contribution
to this area of research over the past nine years. Having recognized the importance of cytointernalizable
matrix ligands for the motility processes in skin cells, his laboratory
published the first series of systematic reports on a model system to
quantitatively describe cell-nanoparticle interactions. Using both experimental and modeling
approaches focused on a collagen-colloidal gold particle system, Dr. Moghe and
his graduate student, Jane Tjia, published four papers from 1999-2000 (Tjia et al., 1999; Tjia and
Moghe, 2002; Tjia and Moghe, 2002; Tjia and Moghe, 2002), which highlighted the following findings: (1)
Nano/submicroscale particles presenting adhesive matrix ligands significantly
activated a motile cell phenotype in terms of cell filopodial morphology and
cytoskeletal organization; and consequently enhanced
cytointernalization-coupled cell migration rates relative to controls
(nanoparticles alone; ligand alone) in a ligand concentration dependent manner
(2) The enhancement in cell migration depended critically on cell-engendered
mobility and cytointernalization of the nanoparticles (3) The rate of cell
migration is correlated to the rate of ligand sampling, in turn, related to the
rate of cell-ligand binding and rate of ligand internalization (4) Matrix
cytointernalization-coupled cell motility is regulated by growth factor
stimulation and reciprocity with cell-secreted matrix (fibronectin).
Given
the limitations of the gold system for long-term applications, since 2003, the
Moghe laboratory developed a new platform based on albumin nanoparticles, which
can be easily metabolized once internalized, can be fabricated to various
sizes; and is easily derivatized with organic ligands. In 2006, Dr. Moghe's team published the
first paper using 100 nm albumin nanoparticles showing that the albumin
nanoparticle core exposes the cell-adhesion domain of III9-10 fibronectin
fragments (Sharma et al., 2006). Keratinocyte
cell adhesion to substrate deposited ligand-nanoparticles resulted in a
prominent F-actin filopodial organization, and cell motility was significantly
enhanced relative to substrate controls with comparable levels of ligand alone.
A subsequent manuscript focuses on the role of variation of nanoparticle size
in induction of ligand/nanoparticle cytointernalization and migration (Nature
Nanotechnology,
Submission 7/06). Smaller
nanoparticles (30-50 nm) further promote cytointernalization dynamics, and thus
promote cell migration kinetics (Sharma et al., 2006).
Separately,
the Moghe laboratory investigated the potential for manipulating dynamic
nanoparticle interactions with integrins, the cell adhesion receptors. Using
dermal fibroblasts, fibronectin fragment presentation from albumin
nanoparticles was found to (1) markedly promote cell elongation and a
contractile phenotype in a ligand concentration dependent manner (Tissue
Engineering,
in review) (2) promote fibrillogenesis/assembly of cell-secreted fibronectin
(3) accelerate the centripetal translocation of beta1 integrins bound to
ligand-nanoparticles, suggesting that the nanoparticle-induced receptor
dynamics correlates with increased cell-assembly of fibronectin (Pereira et al., 2006). Notably, the
nanoparticle effects were abolished if the nanoparticles were merely presented
via solution or if Rac/Rho inhibitors were incorporated, indicating the
importance of cell adhesion and contractile signaling mechanisms for the
biodynamics. A subsequent
manuscript investigates the role of nanoparticle size on the cell contractility
and cell matrix assembly. A
combination of the nanoscale particle effects on cell motility and matrix
assembly processes is being presented in a manuscript (Sharma et al., 2006). The key finding
of this paper is that two scale regimens were found: for smaller
ligand-particles, the biodynamics of internalization was accelerated, while for
larger ligand-particles, biodynamics of membrane clustering, contraction and
assembly was accelerated.
Nanoparticles
for Controlled Cellular Uptake of Lipoproteins
A
prime example of nanoscale interactions of cells and matrix is initiated within
the vascular circulation (blood vessels).
Low density lipoproteins trapped within the vascular intima are
progressively oxidized and modified.
The oxidized LDL is rapidly internalized within blood immune cells such
as macrophages, which transform into foamy cells, secrete cytokines that
trigger the excessive proliferation of smooth muscle cells, and ultimately
undergo apoptosis. These
inflammatory events, in conjunction with thrombosis, escalate the development
of atherosclerotic plaques, and pose a major risk factor for plaque growth,
plaque destabilization, and narrowing of blood vessels (stenosis).
The
Moghe laboratory, in collaboration with Professor Uhrich (Chemistry, Rutgers),
has designed nanoscale self-assembled particles whose backbone chemistry and
architecture can be systematically varied to exhibit controlled amphiphilicity
and anionic groups. The particles are self-assembled from unimers comprised of
acylated derivatives of biocompatible mucic acid conjugated with poly(ethylene
glycol), where anionic functional groups can be derivatized to either
terminus. In a first publication,
such nanoparticles were shown to complex with unoxidized LDL but not with
oxidized LDL (Chnari et al., 2005). A coarse grain
and molecular dynamics simulation study is ongoing to describe the lipoprotein
retentivity of the nanoparticles (Li et al., 2006). Subsequent
studies in the Moghe laboratory report that the anionic nanoparticles reduce
the kinetics of unoxidized LDL by complexation with LDL but reduce the kinetics
of oxidized LDL by binding to scavenger receptors (Chnari et al., 2006). Recent efforts
have identified SRA and CD36 to be the key scavenger receptor targets for the
anionic nanoparticles; consequently, blockage of scavenger receptors by the
nanoparticles reduced cytokine secretion, foam cell formation, and cholesterol
accumulation (Chnari et al., 2006). Certain
characteristics of the nanoparticles were found to be requisite to maximal
scavenger receptor binding. For
example, positioning of anionic groups on hydrophobic termini were found to
reduce oxLDL uptake but not if the anionic groups were displayed from
hydrophobic termini. Recent
studies implicate the size as well as anionic charge density to be important
variables that further accentuate the ability of nanoparticles to inhibit oxLDL
uptake (Wang et al., 2006). These
studies are promising as nanotechnology affords a possible avenue to
effectively alter the dynamics of lipoportein matrix retention within the
intima. Systematic studies of
binding affinities between the nanoparticles and major scavenger receptors are
being pursued using surface plasmon resonance. Further studies are proposed to elucidate how the
nanoparticle structure influences the receptor binding, cross-linking, and possible
conformational changes leading to receptor internalization. The goals are to identify nanoparticle
structures that maximally occupy scavenger receptors with minimal degree of
receptor internalization. Animal
models are currently being tested to examine the potential for the
nanoparticles to reduce inflammation and atherogenesis. The advances in this
project have been highlighted recently by news release from the American
Chemical Society and Nanobiotechnology News, and industrial partnering is
envisioned for successful translation of this project for further development
and possible testing for therapeutic potential.
Characterization
of Cell-Biomaterials Interactions
Current
and Past Members: Dr. Patrick
Johnson, Dr. Robert Dubin, Dr. Charles Chang, Evangelos Tziampazis, Yong Ho
Bae, Ram Sharma, Er Liu, Matthew Treiser
Collaborators: Dr. Joachim Kohn (Chemistry, Rutgers),
Dr. Matthew Becker (NIST), Dr. Sangeeta Bhatia (MIT), Dr. Peter Ma (U.
Michigan), Dr. Treena Arinzeh (NJIT), Dr. Gary Nackman (UMDNJ), Dr. Andres
Garcia (Georgia Tech)
Funding: NIH, NJCST, Rutgers Academic Excellence
Fund, Whitaker Foundation
Between
1996 and 2001, Moghe's group has examined various interactions between white
blood cells and prosthetic materials.
Five publications have appeared quantifying leukocyte adhesive and motility
responsiveness in situ to plasma proteins, flow exposure, and molecular
variations in cell adhesion to materials (e.g. CD43) (Chang et al., 1999; Chang
et al., 2000; Chang et al., 2000; Rosenson-Schloss et al., 2002;
Rosenson-Schloss et al., 1999). Since 1997,
Moghe's group and collaborators from the laboratory of Joachim Kohn at Rutgers
have jointly investigated the cellular interactions with substrates made from
the family tyrosine-derived polycarbonates. These materials can be tailored with different levels of
hydrophobicity, degradation rates, and protein adsorptivity. In the first major report, Moghe et
al., showed that increased levels, within limits, of incorporation of
poly(ethylene glycol) in the polymer backbone weakened cell adhesion strength
and promoted cell motility kinetics (Tziampazis et al., 2000). Subsequent
studies that equalized levels of proteins adsorbed on polycarbonates with
different levels of PEG showed that increased levels of PEG (a) promote cell-mediated
ligand remodeling and exposure of cell adhesive epitopes on the ligand; (b)
enhance cell migration kinetics (Sharma et al., 2004).
Recent
reports from the Moghe laboratory comparing two members of the polyarylate
family of polymers with similar levels of hydrophobicity and glass transition
temperatures, but differing in the presence of a single atom substitution of a
carbon by an oxygen, showed that cell adhesion and motility behavior on the
substrates are identical at all ligand levels except at intermediate ligand
concentrations, where cellular responses were significantly different (Bae et al., 2006). Studies on a
library of combinatorially designed polycarbonate polymers are currently
exploring how the incorporation of PEG, DT (acid), and iodine (for
radio-opacity) modulate cell adhesivity and motility responsiveness (Johnson et al., 2006). To this end, a library of biodegradable, tyrosine-derived
polycarbonates was selected with tunable protein/cell adsorption, X-ray
visibility, and degradability. Three chemical components were selectively
varied through copolymerization: 1) iodine to achieve X-ray visibility; 2)
poly(ethylene glycol) (PEG) to decrease protein adsorption and cell adhesivity;
and 3) DT to increase the degradation rate. In a rapid screening format, the
complex interplay of the chemical components on smooth muscle cell attachment,
motility and proliferation, was investigated. For the base polymer, poly(DTE
carbonate) the progressive incorporation of PEG reduced cell attachment.
However, upon the inclusion of iodine in the tyrosine ring, the PEG effect was
significantly reduced. Furthermore, following copolymerization with 10% of the
DT monomeric derivative containing a free carboxylic acid, the PEG effect was
negated for the iodine containing polymers and reversed for the non-iodinated
polymers. Cross-functional analysis of motility and proliferation revealed
substrate chemistry related cell response regimes. For instance, with the base
poly(DTE carbonate) polymers, increasing PEG levels increased smooth muscle
cell motility at the expense of proliferation. In contrast, for poly(DTE
carbonate) with 10% DT, increasing PEG levels increased cell adhesion,
motility, and proliferation. These studies provide an example of
multidimensional, quantitative cross-functional profiling of cells on
biomaterials-- further correlations are sought for other cell functions in
strategic cell types for cell differentiation and apoptosis.
Moghe's
laboratory has actively employed a variety of high-resolution optical
microscopy approaches to elucidate cell-material interactions, including
confocal laser-scanning microscopy (CLSM), atomic force microscopy (AFM), and
recently, multi-photon microscopy (MPM).
In earlier reports, Moghe et al, quantified polymer scaffold
microstructure using fluorescence and reflection mode CLSM both pre- and
post-degradation (Semler et al., 1997; Tjia
and Moghe, 1998), while more recently, they
have authored a manuscript focused on microstructure analysis of scaffolds of
blends of poly(DTE carbonates) and poly(DTO carbonates), that shows the
increased signal-to-noise ratio, biorelevant cell characterization, and
quantitative capabilities of MPM relative to CLSM (Liu et al., 2006). The imaging
methods are also being applied to fluorescently engineered cells on
biomaterials, as described next.
Moghe's
studies on cell profiling on biomaterials are integral to the NIH program grant
on Integrated Resources for Polymeric Materials. Two major toolboxes are being assembled under Moghe's
directorship and in conjunction with collaborators toward the building of a cell-biomaterials
interactome. The first is a suite
of imaging and image analysis modalities assembled on the multiphoton
microscope. The imaging platform
is currently a 100-grid chamber assembled in collaboration with NIST using a
optically active adhesive glue to create a chamber where polymers can be
deposited and cell dynamics studies using real-time MPM. The imaging modality consists of
generation of genetically engineered fluororeporter cell lines, which express
cell morphologic, cytoskeletal, and differentiation markers. A manuscript under preparation for
submission to Nature Methods summarizes for over one-hundred compositions on
gradients of polymer blends, the reporter profiling for several successful cell
lines, which respond sensitively to changes in biomaterial chemistry (Treiser et al., 2006). The advantage of
such fluororeporters is that for each fluororeporter, up to hundred cell
descriptors can be quantified using fluorescent imaging and image
analysis. A major endeavor is
currently underway to identify the descriptors that discern these biomaterial
features: an example is the identification of descriptors that resolve
incorporation of PEG and DT, both singly and together, in relation to poly(DTE
carbonates). Once such descriptors
are identified, they are rank ordered via decision tree analysis in relation to
cell functions, such as cell proliferation, motility, and apoptosis. Thus, a family of key
biomaterial-responsive cell descriptors can be identified for each strategic
cell function. Cross co-relations
between such descriptors can be examined for the selective amplification or
suppression of certain functions.
These ideas, in conjunction with systems biology concepts, are being
investigated further within the paradigm of modeling of cell-material
interactome (Kohn and Moghe, 2006).
Publications
can be downloaded from a tabulated list on-line at: http://www.rci.rutgers.edu/~moghe/Publications.html
BIBLIOGRAPHY
(Recent
Publications of Dr. Moghe and coworkers, and Key Citations)