Drug Delivery Projects
The following are examples of our drug delivery
projects that have been published. We are currently pursuing these and other
areas of related research. We consider our biomaterials
research to be drug delivery research.
- Cervical cancer treatment with a locally insertable controlled release
system
- Matrix metalloprotease triggered
local delivery of cancer chemotherapeutics from hydrogel matrixes
- Extracellular protease activation
of chemotherapeutics from hydrogel matrices: A new paradigm for local
chemotherapy
- Cisplatin Delivery From Poly(Acrylic
Acid-co-Methyl Methacrylate) Microparticles
- Development of amine-containing
polymeric nanoparticles
- Assessment of a Modular
Transfection System based upon Cellular Localization of DNA
- Cellular Fate of a Modular DNA Delivery
System Mediated by Silica Nanoparticles
Cervical
cancer treatment with a locally insertable controlled release system
Keskar, Mohanty, Gemeinhart and Gemeinhart
[back to top]
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Manuscript |
Abstract: Local delivery of cancer chemotherapeutics
enables sustained drug levels at the site of action thereby reducing
systemic side effects. A novel insertable polymeric drug delivery
system for cervical cancer treatment is presented. Cisplatin, the
first line of therapy employed for cervical cancers, was incorporated
in a poly(ethylene-co-vinyl acetate) (EVAc) device that is similar
to those currently used for vaginal contraceptive delivery. Cisplatin
crystals were uniformly dispersed in the polymeric system without
undergoing significant dissolution in the polymer matrix. Cisplatin
dissolution from the devices was biphasic, consistent with a matrix-type
controlled-release system with an initial rapid release phase followed
by a slower, linear release phase. Depending on the drug loading in
the polymeric devices, the near-linear release phase varied in rate
according both empirical, linear curve-fitting (0.38±0.15 µg/day
to 46.9±10.0 µg/day) and diffusion analysis based upon
diffusion through a porous structure (Dapp from 1.3±0.5x10-9
cm2/s to 5.8±0.3x10-12 cm2/s). The devices were tested for
in vitro activity and found to be effective against both HPV positive
and HPV negative cervical cancer cell lines. Preliminary studies indicate
that this delivery system would be a good candidate for investigation
as a choice of treatment in cervical cancers.
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Matrix
metalloprotease triggered local delivery of cancer chemotherapeutics
from hydrogel matrixes
Tauro and Gemeinhart
[back to top]
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Manuscript |
Abstract: Glioblastoma Multiforme (GBM)
is a highly advanced and invasive brain tumor due to which current
treatments cannot completely treat GBM or prevent recurrence. Therefore,
adjunctive treatments are required. As part of the invasive and angiogenic
nature of GBM, it has been well established that matrix metalloprotease-2
(MMP-2) and MMP-9 are overactive. To better treat GBM using chemotherapy,
we have designed a hydrogel-based delivery system which can control
the release of drugs based on the activity of MMPs. A model chemotherapeutic
agent, cisplatin, complexed to an MMP substrate (peptide-linker) was
incorporated into poly(ethylene glycol) diacrylate hydrogel wafers
having different poly(ethylene glycol) chain lengths (Mn ~574 and
4000). Hydrogel wafers were studied for physical characteristics and
drug release in the presence and absence of MMPs. There was a substantial
increase in cisplatin release for the poly(ethylene glycol) 4000 hydrogel
indicating that this chain length provides a mesh size that is sufficient
to permit MMP activity within the hydrogel. Cisplatin bioactivity
increased when the cell media was spiked with MMPs (0% cell survival)
in case of the longer chain length as compared to in the absence of
MMPs (approximately 50% cell survival). The results suggest that this
system can be used for selective, local delivery of drugs where higher
amounts of the drug are released in response to metastasis, angiogenesis,
and invasion promoting proteases. This strategy may prove to be a
novel and effective method to overcome inadequacies in current controlled
drug release systems.
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Extracellular
protease activation of chemotherapeutics from hydrogel matrices: A
new paradigm for local chemotherapy
Tauro and Gemeinhart
[back to top]
| 
Manuscript |
Abstract: A novel paradigm for local
cancer chemotherapy, based upon local activation of chemotherapeutic
molecules by soluble proteases, is presented. In the presence of matrix
metalloproteases, a family of cancer-associated proteases, cisplatin
is release from a hydrogel matrix in an active form. In the absence
of matrix metalloproteases, cisplatin is released at a much lower
rate. The mesh size of the polymer controls metalloprotease-based
cisplatin release from the hydrogel matrix with approximately doubling
of cisplatin release in the presence of matrix metalloprotease. Overall,
this novel paradigm shows much potential for local chemotherapy where
local chemotherapeutic release is in response to the invasive properties
of the tumor.
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Cisplatin
Delivery From Poly(Acrylic Acid-co-Methyl Methacrylate) Microparticles
Yan and Gemeinhart
[back to top]
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Manuscript |
Abstract: To develop a platform for tumor
chemotherapy, poly(acrylic acid-co-methyl methacrylate) microparticles
have been synthesized. Carboxylate containing monomers were included
to complex therapeutic agents, specifically cisplatin. Microparticles
were prepared by free radical emulsion polymerization in aqueous media.
Particle diameter, -potential, in vitro cytotoxicity, and in vivo
acute toxicity were characterized for both cisplatin-loaded microparticles
and unloaded microparticles. In vitro cytotoxicity and FT-IR were
used to characterize cisplatin released from cisplatin-loaded microparticles.
Acrylic acid feed mole fraction determined several key microparticle
properties, including particle size, -potential, and yield. A burst
release of cisplatin (40%) in the first day was followed by a zero-order
release phase. The interaction between cisplatin and microparticles
allowed approximately 20% additional cisplatin release in the next
five days. Cisplatin-loaded and unloaded microparticles are non-toxic
(LC50 > 15 mM) to the cell line used in in vitro tests. Cisplatin
released from cisplatin-loaded microparticles retained activity, but
that activity was slightly lower than freshly prepared cisplatin.
Other than a slight reduction in cisplatin activity, microparticles
exhibited low in vivo acute toxicity (LD50 > 170 mg/kg), which suggests
that this hydrogel particulate system and the hydrogel complexation
mechanism should further be studied for drug delivery.
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Development
of amine-containing polymeric nanoparticles
Tauro and Gemeinhart
[back to top]
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Manuscript |
Abstract: The objective of this study
was to synthesize and characterize particles as a drug delivery platform
for gliomas, a highly advanced and invasive stage of brain tumor with
poor prognosis. Poly(aminoethyl methacrylate-co-methyl methacrylate)
particles were prepared by suspension polymerization and poly(aminoethyl
methacrylate-co-poly(ethylene glycol) methacrylate) particles were
prepared by emulsion (w/o) polymerization. Amine groups of the particles
were complexed with tetrachloroplatinate to form a cisplatin-like
molecule. Particles were characterized with respect to size, -potential,
amine content, loading efficiency and drug release. Poly(aminoethyl
methacrylate-co-methyl methacrylate) particles had diameters of below
10 µm, whereas the poly(aminoethyl methacrylate-co-poly(ethylene glycol)
methacrylate) particles had diameters of approximately 1 µm. Poly(aminoethyl
methacrylate-co-poly(ethylene glycol) methacrylate) particles had
a more positive -potential as compared to poly(aminoethyl methacrylate-co-methyl
methacrylate) particles, although the amino group content of both
particles was almost equivalent. The net positive charge on the particles
decreased after complexation with tetrachloroplatinate for both types
of particles. Both particles had very high platinum loading efficiency
(>85%) and showed slow release of platinum over time. Particles had
relatively low cytotoxicity (LC50 > 100 µg/mL) and demonstrated a
high degree of association with cells. Complexation with poly(aminoethyl
methacrylate-co-methyl methacrylate) particles significantly reduced
the toxicity of platinum. The poly(aminoethyl methacrylate-co-poly(ethylene
glycol) methacrylate) particles have potential for being an effective
drug delivery platform and continued investigation is warranted.
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Assessment
of a Modular Transfection System based upon Cellular Localization
of DNA
Guo and Gemeinhart
[back to top]
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Manuscript |
Abstract: Delivery of plasmid DNA for
protein production in mammalian cells is not an efficient process.
In this study, the theory that cellular localization of plasmid DNA
increases transfection efficiency is examined with an emphasis on
the understanding of the cellular association of the components of
a ternary transfection complex. Mammalian cells take up transfection
reagent-DNA complexes primarily from their local environment. By complexing
DNA-transfection reagent into a ternary complex with a heavy particle,
such as silica, the efficiency of transfection is substantially increased.
We have analyzed cells transfected with the ternary complexes to determine
if sedimentation alone affects the percentage of cells that contain
the complexes or specific components of the complex. A significant
fraction of cells associate with the ternary complexes including silica
nanoparticles. The percentage of cells that associate with DNA was
not significantly influenced by the use of the ternary complex. This
result suggests that the role of the silica nanoparticles is more
than just a sedimentation agent, but the silica nanoparticles are
a secondary transfection reagent. This data also confirms that cells
may contain transfection reagent-DNA complex but do not express the
protein of interest. This knowledge will be used in further research
to better design transfection reagents that will increase the efficiency
of protein production.
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Cellular
Fate of a Modular DNA Delivery System Mediated by Silica Nanoparticles
Gemeinhart, Luo, and Saltzman
[back to top]
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Manuscript |
| Abstract: Development of efficient molecular
medicines, including gene therapeutics, RNA therapeutics, and DNA
vaccines, depends upon efficient means of transfer of DNA or RNA into
the cell. Potential problems, including toxicity and immunogenicity,
surrounding viral methods of DNA delivery have necessitated the use
of non-viral, synthetic carriers. To better design synthetic carriers,
or transfection reagents, the modular design of viruses has inspired
a modular approach to DNA and RNA delivery. Each modular component
can be designed to circumvent each of the many barriers. The modular
approach will allow modification of individual components for a specific
application. By utilizing a dense silica nanoparticle to form a ternary
complex, transfection efficiency of a DNA-transfection reagent complex
was increased by a factor of approximately 10 by concentrating the
DNA at the surface of cells. Surface modification of the silica nanoparticles
allowed determination of the cellular uptake mechanism with only minor
alteration of transfection efficiency. Nanoparticles are internalized
by an endosome-lysosomal route followed by perinuclear accumulation.
The modification mechanism confirms that surface modification of the
modular system can allow specific moieties to be incorporated into
the modular system without significant alteration of the transfection
efficiency. By showing that the modular system based upon concentration
of DNA at the level of the cell can be used to increase transfection
efficiency, we have shown that further modification of the system
may better target DNA delivery and overcome other barriers of DNA
expression. |
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