Developing
systems
capable of controlled and efficient gene
transfer is a fundamental goal of biotechnology, with applications
ranging from
basic science to clinical medicine. The successful application to basic
science
and clinical medicine requires the ability to manipulate the expression
of
target genes, either up or down, in the desired cell population. The
expression
level for a gene of interest can be increased through delivery of a
plasmid
encoding for that gene or can be decreased using antisense
oligonucleotides
that limit messenger RNA stability and translation. We are
investigating two
alternative delivery strategies: sustained delivery and substrate
immobilization.
Sustained delivery can function to maintain the extracellular
concentration and
provide extended opportunities for cellular internalization.
Substrate-mediated
delivery increases the concentration of DNA within the cellular
microenvironment.
In these approaches, the polymers function to regulate the
biodistribution,
which can be combined with the packaging approaches that facilitate
cellular
internalization and trafficking.
Severe nerve
damage, an
injury that affects many thousands of
patients each year, often results in loss of function, such as
paralysis below
the level of the injury. A crush injury to central nervous system (CNS)
neurons
can result in massive cell death and produce a cyst and glial scar that
pose a
formidable barrier to nerve regeneration. CNS neurons have the capacity
for
regeneration; however, the current strategies for augmenting nerve
regeneration
following injury have met with limited success. We are developing
polymer
scaffolds that can be used to stimulate the appropriate cellular
processes, or
can be used as a cell transplantation vehicle. Tubes with either an
empty lumen
or porous polymer scaffolds are being fabricated that function to limit
invasion of inappropriate cell type, support cell adhesion and
migration, and
also serve as a vehicle for the delivery of bioactive factors (e.g.,
protein
growth factors or plasmid DNA). Direct injection of the factors or
delivery
using a pump has some limitations which may be overcome with controlled
release
systems. Additionally, the use of the three-dimensional scaffold as the
delivery vehicle provides a means to spatially and temporally regulate
the concentration
of multiple tissue inductive factors. The scaffolds have the potential
to
create an environment that excludes the factors that inhibit
regeneration and
provides the factors that stimulate neurite outgrowth.
(Researchers: Dr. Anne des Rieux,
Yang
Yang, Tiffany
Houchin, Laura
DeLaporte, Kanika Bhatia, Hannah
Tuinstra)
In Vitro Ovarian Follicle Maturation In vitro culture
systems for the maturation of follicles are needed for
the treatment of
infertility resulting from
diseases that affect the ovary or cancer therapeutics. Immature
follicles consist of an oocyte surrounded by one or two layers of
granulosa cells. The goal of this project is to employ a
three-dimensional, engineered, synthetic stroma to examine granulosa
cell-oocyte complexes (GOC) maturation and development in vitro. Oocyte
maturation and granulosa cell development involve endocrine, paracrine,
and autocrine-acting factors in addition to appropriate somatic-germ
cell and somatic cell-matrix interactions. The native stroma
surrounding a GOC dynamically regulates growth and maturation by
maintaining cellular interactions and providing the matrix interactions
that direct cell function. Currently used two-dimensional culture
systems do not adequately retain the three-dimensional architecture. A
synthetic scaffold can serve as a stroma that creates a cellular
environment designed to provide the factors that stimulate maturation
of the GOCs, but lacks the factors found in the native stroma that
inhibit GOC maturation. Synthetic scaffolds can be created which
maintain the appropriate size, shape and architecture of the tissue
while providing the necessary signals to direct cellular responses.
Importantly, synthetic three-dimensional scaffolds could function to
maintain the intimate physiological connections between the oocytes and
somatic cells within the GOC, which are essential for normal
development.
(Researchers: Erin West, Elizabeth Parrish, Leo Mosquea) Islet Cell Transplantation The
recent clinical successes using islet cell transplantation have
demonstrated
that cell replacement therapy has the potential to be a viable
treatment for
type 1 diabetes. Current clinical approaches deliver islets through the
portal
vein and subsequently reside within the sinusoids of the liver. This
approach
requires large numbers of islets due to limited survival or
hypofunctionality
of the islets following transplantation, and the islets result in
steatosis
that has unknown long-term effects on the liver. The objectives of this
research are to use drug-releasing scaffolds to enhance engraftment,
survival,
and function of transplanted islets. The scaffolds provide a support
for islet
cell attachment, and factors are delivered that can create a
microenvironment
that will support islet cell function and integration with the host
tissue.
(Researchers: Chris
Rives, David
Salvay) |