methylcellulose and Stroke

We developed a biocomposite that can be mixed with brain-derived neurotrophic factor (BDNF) and dispensed onto the surface of the brain to provide sustained, local release of the protein using a procedure that avoids additional damage to neural tissue. The composite is simple to fabricate, and provides sustained release without nanoparticle encapsulation of BDNF, preserving material and protein bioactivity. We demonstrate that when delivered epicortically to a rat model of stroke, this composite allows BDNF to diffuse into the brain, resulting in enhanced behavioral recovery and synaptic plasticity in the contralesional hemisphere.

Topics: Animals; Behavior, Animal; Brain; Brain-Derived Neurotrophic Factor; Drug Delivery Systems; Hindlimb; Hyaluronic Acid; Male; Methylcellulose; Neurons; Polylactic Acid-Polyglycolic Acid Copolymer; Rats, Sprague-Dawley; Recovery of Function; Stroke; Synaptophysin

The utility of stem cells and their progeny in adult transplantation models has been limited by poor survival and integration. We designed an injectable and bioresorbable hydrogel blend of hyaluronan and methylcellulose (HAMC) and tested it with two cell types in two animal models, thereby gaining an understanding of its general applicability for enhanced cell distribution, survival, integration, and functional repair relative to conventional cell delivery in saline. HAMC improves cell survival and integration of retinal stem cell (RSC)-derived rods in the retina. The pro-survival mechanism of HAMC is ascribed to the interaction of the CD44 receptor with HA. Transient disruption of the retinal outer limiting membrane, combined with HAMC delivery, results in significantly improved rod survival and visual function. HAMC also improves the distribution, viability, and functional repair of neural stem and progenitor cells (NSCs). The HAMC delivery system improves cell transplantation efficacy in two CNS models, suggesting broad applicability.

Topics: Animals; Blindness; Cell Survival; Hyaluronan Receptors; Hyaluronic Acid; Hydrogel, Polyethylene Glycol Dimethacrylate; Immunohistochemistry; Methylcellulose; Mice; Mice, Inbred C57BL; Mice, Knockout; Real-Time Polymerase Chain Reaction; Retina; Retinal Rod Photoreceptor Cells; Rhodopsin; Stem Cell Transplantation; Stem Cells; Stroke

Drug delivery to the central nervous system is limited by the blood-brain barrier, which can be circumvented by local delivery. In applications of stroke therapy, for example, stimulation of endogenous neural stem/progenitor cells (NSPCs) by cyclosporin A (CsA) is promising. However, current strategies rely on high systemic drug doses to achieve small amounts of CsA in the brain tissue, resulting in systemic toxicity and undesirable global immunosuppression. Herein we describe the efficacy of local CsA delivery to the stroke-injured rat brain using an epi-cortically injected hydrogel composed of hyaluronan and methylcellulose (HAMC). CsA was encapsulated in poly(lactic-co-glycolic acid) microparticles dispersed in HAMC, allowing for its sustained release over 14days in vivo. Tissue penetration was sufficient to provide sustained CsA delivery to the sub-cortical NSPC niche. In comparison to systemic delivery using an osmotic minipump, HAMC achieved higher CsA concentrations in the brain while significantly reducing drug exposure in other organs. HAMC alone was beneficial in the stroke-injured rat brain, significantly reducing the stroke infarct volume relative to untreated stroke-injured controls. The combination of HAMC and local CsA release increased the number of proliferating cells in the lateral ventricles - the NSPC niche in the adult brain. Thus, we demonstrate a superior method of drug delivery to the rat brain that provides dual benefits of tissue protection and endogenous NSPC stimulation after stroke.

Topics: Animals; Blood-Brain Barrier; Brain Infarction; Cell Count; Cyclosporine; Drug Compounding; Drug Delivery Systems; Hyaluronic Acid; Hydrogels; Immunosuppressive Agents; Lactic Acid; Lateral Ventricles; Male; Methylcellulose; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Rats; Rats, Long-Evans; Stem Cells; Stroke

Stroke is a leading cause of disability with no effective regenerative treatment. One promising strategy for achieving tissue repair involves the stimulation of endogenous neural stem/progenitor cells through sequential delivery of epidermal growth factor (EGF) followed by erythropoietin (EPO). Yet currently available delivery strategies such as intracerebroventricular (ICV) infusion cause significant tissue damage. We designed a novel delivery system that circumvents the blood brain barrier and directly releases growth factors to the brain. Sequential release of the two growth factors is a key in eliciting tissue repair. To control release, we encapsulate pegylated EGF (EGF-PEG) in poly(lactic-co-glycolic acid) (PLGA) nanoparticles and EPO in biphasic microparticles comprised of a PLGA core and a poly(sebacic acid) coating. EGF-PEG and EPO polymeric particles are dispersed in a hyaluronan methylcellulose (HAMC) hydrogel which spatially confines the particles and attenuates the inflammatory response of brain tissue. Our composite-mediated, sequential delivery of EGF-PEG and EPO leads to tissue repair in a mouse stroke model and minimizes damage compared to ICV infusion.

Topics: Absorbable Implants; Animals; Brain; Delayed-Action Preparations; Drug Delivery Systems; Epidermal Growth Factor; Erythropoietin; Humans; Lactic Acid; Male; Methylcellulose; Mice; Mice, Inbred C57BL; Nanoparticles; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Recombinant Proteins; Regeneration; Stroke

Stimulation of endogenous neural stem/progenitor cells (NSPCs) with therapeutic factors holds potential for the treatment of stroke. Cyclosporin A (CsA) is a particularly promising candidate molecule because it has been shown to act as a survival factor for these cells over a period of weeks both in vitro and in vivo; however, systemically-delivered CsA compromises the entire immune system, necessitating sustained localized delivery. Herein we describe a local delivery strategy for CsA using an epi-cortical hydrogel of hyaluronan-methylcellulose (HAMC) as the drug reservoir. Three methods of incorporating the drug into the hydrogel (solubilized, particulate, and poly(lactic-co-glycolic) acid (PLGA) microsphere-encapsulated) resulted in tunable release, spanning a period of hours to weeks. Importantly, PLGA-encapsulated CsA released from the hydrogel had equivalent bioactivity to fresh drug as measured by the neurosphere assay. Moreover, when CsA was released from the PLGA/HAMC composite that was injected on the cortex of adult mice, CsA was detected in the NSPC niche at a constant concentration for at least 24days post-implant. Thus this hydrogel composite system may be promising for the treatment of stroke.

Topics: Animals; Brain; Chromatography, Liquid; Cyclosporine; Delayed-Action Preparations; Drug Delivery Systems; Hyaluronic Acid; Hydrogels; Lactic Acid; Methylcellulose; Mice; Mice, Inbred C57BL; Microscopy, Electron, Scanning; Microspheres; Models, Biological; Neural Stem Cells; Particle Size; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Solubility; Stroke; Surface Properties; Tandem Mass Spectrometry; Time Factors

Drug delivery to the brain is challenging because systemic delivery requires high doses to achieve diffusion across the blood-brain barrier and often results in systemic toxicity. Intracerebroventricular implantation of a minipump/catheter system provides local delivery, yet results in brain tissue damage and can be prone to infection. An alternate local delivery strategy, epi-cortical delivery, releases the biomolecule directly to the brain while causing minimal tissue disruption. We pursued this strategy with a hyaluronan/methyl cellulose (HAMC) hydrogel for the local release of erythropoietin to induce endogenous neural stem and progenitor cells of the subventricular zone to promote repair after stroke injury in the mouse brain. Erythropoeitin promotes neurogenesis when delivered intraventricularly, thereby making it an ideal biomolecule with which to test this new epi-cortical delivery strategy. We investigated HAMC in terms of the host tissue response and the diffusion of erythropoeitin therefrom in the stroke-injured brain for neural repair. Erythropoietin delivered from HAMC at 4 and 11 days post-stroke resulted in attenuated inflammatory response, reduced stroke cavity size, increased number of both neurons in the peri-infarct region and migratory neuroblasts in the subventricular zone, and decreased apoptosis in both the subventricular zone and the injured cortex. We demonstrate that HAMC-mediated epi-cortical administration is promising for minimally invasive delivery of erythropoeitin to the brain.

Topics: Animals; Apoptosis; Brain; Cell Count; Cerebral Cortex; DNA-Binding Proteins; Doublecortin Domain Proteins; Drug Administration Routes; Drug Delivery Systems; Erythropoietin; Humans; Hyaluronic Acid; Hydrogel, Polyethylene Glycol Dimethacrylate; In Situ Nick-End Labeling; Inflammation; Ki-67 Antigen; Methylcellulose; Mice; Mice, Inbred C57BL; Microtubule-Associated Proteins; Nerve Tissue Proteins; Neuropeptides; Nuclear Proteins; Receptors, Erythropoietin; Stem Cells; Stroke