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1.  An Anti-angiogenic Reverse Thermal Gel as a Drug-Delivery System for Age-Related Wet Macular Degenerationa 
Macromolecular bioscience  2013;13(4):464-469.
Reverse thermal gels have numerous biomedical implications, as they undergo physical gelation upon temperature increases and can incorporate biomolecules to promote tissue repair. Such a material is developed for the sustained release of bevacizumab (Avastin), a drug used to treat age-related macular degeneration. The polymer, poly(ethylene glycol)-poly-(serinol hexamethylene urethane) (ESHU), forms a physical gel when heated to 37 °C and shows good cytocompatibility with ocular cells. ESHU is capable of sustaining bevacizumab release over 17 weeks in vitro, and the release kinetics can be altered by changing the drug dose and the ESHU concentration. These results suggest that ESHU is biologically safe, and suitable for ocular drug delivery.
PMCID: PMC4142681  PMID: 23316011
age-related wet macular degeneration; compatibility; hydrogels; retinal cells; sustained release
2.  Biocompatible Reverse Thermal Gel Sustains the Release of Intravitreal Bevacizumab In Vivo 
We assessed the in vivo release profile of bevacizumab from and biocompatibility of poly(ethylene glycol)-poly-(serinol hexamethylene urethane), or ESHU, a thermoresponsive hydrogel administered intravitreally for drug delivery.
The technical feasibility of injection was assessed quantitatively via mechanical testing. For in vivo studies, New Zealand White rabbit eyes were injected intravitreally with 0.05 mL of either: ESHU dissolved in 25 mg/mL bevacizumab, ESHU dissolved in PBS, or 25 mg/mL bevacizumab. Clinical examination included IOP measurements and examination with indirect ophthalmoscopy for signs of inflammation. Additionally, eyes were examined histologically following euthanasia. To quantify bevacizumab release, aqueous humor samples were obtained via anterior chamber paracentesis and ELISA was used to determine the concentration of drug weekly. In vitro cytotoxicity testing also was performed using bovine corneal endothelial cells.
The ESHU was injected easily through a 31-gauge needle, was well tolerated in vivo, and caused minimal cell death in vitro when compared to other common materials, such as silicone oil. The long-term presence of the gel did not affect IOP, and there was no evidence of inflammation histologically or through indirect observation. The ESHU sustained the release of bevacizumab for over 9 weeks and maintained a drug concentration that averaged 4.7 times higher than eyes receiving bolus bevacizumab injections.
To our knowledge, this is the first report demonstrating sustained bevacizumab release in vivo from an intravitreally injected hydrogel formulation, suggesting that this delivery system may be a promising candidate for ocular drug delivery.
In this study, we studied the sustained release of bevacizumab from an injectable, thermally responsive hydrogel in vivo, and assessed the biocompatibility of the gel in rabbit eyes.
PMCID: PMC3901415  PMID: 24370837
thermally responsive hydrogel; ocular drug delivery; sustained release; biocompatibility; injectable gel
3.  Peripheral Hyperstimulation Alters Site of Disease Onset and Course in SOD1 Rats 
Neurobiology of disease  2010;39(3):252-264.
In amyotrophic lateral sclerosis (ALS), the exogenous temporal triggers that result in initial motor neuron death are not understood. Overactivation and consequent accelerated loss of vulnerable motor neurons is one theory of disease initiation. The vulnerability of motor neurons in response to chronic peripheral nerve hyperstimulation was tested in the SOD1G93A rat model of ALS. A novel in vivo technique for peripheral phrenic nerve stimulation was developed via intra-diaphragm muscle electrode implantation at the phrenic motor endpoint. Chronic bilateral phrenic nerve hyperstimulation in SOD1G93A rats accelerated disease progression, including shortened lifespan, hastened motor neuron loss and increased denervation at diaphragm neuromuscular junctions. Hyperstimulation also resulted in focal decline in adjacent forelimb function. These results show that peripheral phrenic nerve hyperstimulation accelerates cell death of vulnerable spinal motor neurons, modifies both temporal and anatomical onset of disease, and leads to involvement of disease in adjacent anatomical regions in this ALS model.
PMCID: PMC2910141  PMID: 20381620
motor neuron; neurodegeneration; ALS; amyotrophic lateral sclerosis; SOD1; phrenic nerve; diaphragm; diaphragm pacing; diaphragm stimulation; respiratory; disease onset; environment
4.  Focal Transplantation-based Astrocyte Replacement is Neuroprotective in a Model of Motor Neuron Disease 
Nature neuroscience  2008;11(11):1294-1301.
Cellular abnormalities in amyotrophic lateral sclerosis (ALS) are not limited to motor neurons. Astrocyte dysfunction occurs in human ALS and SOD1G93A animal models. Therefore, the value of focal enrichment of normal astrocytes was investigated using transplantation of lineage-restricted astrocyte precursors, Glial-Restricted Precursors (GRPs). GRPs were transplanted around cervical spinal cord respiratory motor neuron pools, the principal cells responsible for death in this neurodegenerative disease. GRPs survived in diseased tissue, differentiated efficiently into astrocytes, and reduced microgliosis in SOD1G93A rat cervical spinal cord. GRPs extended survival and disease duration, attenuated motor neuron loss, and slowed declines in fore-limb motor and respiratory physiological function. Neuroprotection was mediated in part by the primary astrocyte glutamate transporter, GLT1. These findings demonstrate the feasibility and efficacy of transplantation-based astrocyte replacement, and show that targeted multi-segmental cell delivery to cervical spinal cord is a promising therapeutic strategy for slowing focal motor neuron loss associated with ALS.
PMCID: PMC2656686  PMID: 18931666
stem cell; grafting; transplantation; motor neuron; neurodegeneration; replacement; neuroprotection; non-cell autonomous; astroglia; astrocyte; neural precursor cell; progenitor; lineage-restricted precursor; glial precursor; ALS; amyotrophic lateral sclerosis; SOD1

Results 1-4 (4)