Specialized vasculature in the rostral migratory stream as a neurogenic niche and scaffold for neuroblast migration.

Neurovascular niches serve as the hosts for adult neural stem cells in both the hippocampus and subventricular zone. The rostral migratory stream (RMS) vasculature has been found to be important for neuroblast migration, while its roles in hosting putative neural stem cells have not been investigated. Here we investigated the organization of RMS vasculature and its contribution to the production of new neurons. A single pulse of bromodeoxyuridine (BrdU) administration revealed locally formed new neurons within RMS were located adjacent to blood vessels. In addition, BrdU label-retaining cells that are putative neural stem cells were also found close to the vasculature. Sodium fluorescein perfusion assay demonstrated that the blood-brain barrier (BBB) organization was especially "leaky" in the neurogenic niches. Immunohistochemical visualization of some BBB component molecules indicated a thinner BBB in the RMS region, compared to that in the frontal cortex of adult rats. Finally, the expression of vascular endothelial growth factor was strong and specialized in the RMS region, implying that the region was active in cell proliferation and migration. Here we show that the RMS vasculature associated with surrounding astrocytes provides a highly organized neurovascular niche for adult neural stem cell proliferation, in addition to the function of neuroblast migration support. This result points to a new vasculature supporting neurogenic region in the brain.

AC5 Surgical Hemostat™ as an effective hemostatic agent in an anticoagulated rat liver punch biopsy model.

Intra-operative and postoperative bleeding is a major concern in surgical procedures for patients taking anticoagulant medications, or where anticoagulants are used to prevent potential life-threatening embolic complications. Heparin is the anticoagulant used most frequently and has an immediate effect on blood clotting, lasting 4 to 6h. Although synthetic self-assembling peptides have been shown to achieve rapid hemostasis in small animals, none have adequately addressed the potential for hemostasis in the presence of anticoagulant therapy in-vivo. Our goal was to investigate the hemostatic activity of a known synthetic self-assembling peptide in animals treated and untreated with heparin anticoagulation therapy. Using a rat liver puncture model, animals were treated with known synthetic peptide AC5 Surgical Hemostatic Device™, or saline controls. Time-to-hemostasis and coagulation times were recorded in both heparinized and non-heparinized animals. Here we show that AC5™ was able to achieve rapid hemostasis equivalently in both heparinized and non-heparinized animals. FROM THE CLINICAL EDITOR: Intra-operative and postoperative bleeding is a major concern in surgical procedures for patients taking anticoagulant medications. In this work the effective hemostasis was demonstrated both in heparinized and non-heparinized animals using self-assembling peptides.

A self-assembling nanomaterial reduces acute brain injury and enhances functional recovery in a rat model of intracerebral hemorrhage.

There is no effective treatment for intracerebral hemorrhage (ICH). Intracerebral delivery of nanomaterials into the hemorrhagic lesion may be a new therapeutic strategy. In a rat model of ICH plus ultra-early hematoma aspiration, we found that locally delivered self-assembling peptide nanofiber scaffold (SAPNS) replaced the hematoma, reduced acute brain injury and brain cavity formation, and improved sensorimotor functional recovery. SAPNS serves as biocompatible material in the hemorrhagic brain cavity. Local delivery of this nanomaterial may facilitate the repair of ICH related brain injury and functional recovery. From the clinical editor: In a rat model of intracranial hemorrhage, these authors demonstrate that following ultra-early hematoma aspiration, local delivery of a self-assembling peptide nanofiber scaffold replaces the hematoma, reduces brain cavity formation, and improves sensorimotor functional recovery. Similar approaches would be welcome additions to the clinical treatment of this often devastating condition.

Carbon nanotubes: their potential and pitfalls for bone tissue regeneration and engineering.

The extracellular environment which supports cell life is composed of a hierarchy of maintenance, force and regulatory systems which integrate from the nano- through to macroscale. For this reason, strategies to recreate cell supporting environments have been investigating the use of nanocomposite biomaterials. Here, we review the use of carbon nanotubes as part of a bottom-up approach for use in bone tissue engineering. We evaluate the properties of carbon nanotubes in the context of synthetic tissue substrates and contrast them with the nanoscale features of the extracellular environment. Key studies are evaluated with an emphasis on understanding the mechanisms through which carbon nanotubes interact with biological systems. This includes an examination of how the different properties of carbon nanotubes affect tissue growth, how these properties and variation to them might be leveraged in regenerative tissue therapies and how impurities or contaminates affect their toxicity and biological interaction. FROM THE CLINICAL EDITOR: In this comprehensive review, the authors describe the status and potential applications of carbon nanotubes in bone tissue engineering.

The microglial system in the eye and brain in response to stimuli in vivo.

Microglial cells function as first responders to signal inflammation, react to injuries by creating a wall to block invaders, and clear debris from the site. To better understand the modulation of microglia in inflammation and injury of eye and brain, we developed a morphological and orienting classification system of each stage of microglia, calling it the 'Spider Effect'. We transected the olfactory bulb of rats and examined the activation of the microglial system histologically. Six stages of bidirectional microglial activation (A) and deactivation (R) were observed. Our findings support a morphologically defined stepwise activation and deactivation of microglia cells. This relates to inflammation in the eye due to noxious stimuli, injury, or increase in pressure. Future studies may address the reported modulation of the microglial system in retina and optic nerve head in acute and chronic glaucoma.

Rat model of intracerebral hemorrhage permitting hematoma aspiration plus intralesional injection.

A combination of hematoma aspiration and local delivery of chemicals may be more effective than either therapy in intracerebral hemorrhage (ICH). The aim of the present study was to develop a rat model of hematoma aspiration plus intralesional injection after ICH. ICH was induced in adult Sprague-Dawley rats by an intrastriatal injection of bacterial collagenase IV. Hematoma aspiration was performed 3.5 h after ICH onset. Following aspiration, normal saline was injected into the lesion cavity. Hematoma aspiration with or without subsequent saline injection significantly reduced the hematoma volume, lesion volume, and perihematomal neutrophil infiltration. Hematoma aspiration plus subsequent intralesional injection is simple, feasible, and safe. This ICH model can be used to assess the effectiveness of hematoma removal plus local delivery of chemicals.

Nanomedicine for treatment of diabetes in an aging population: state-of-the-art and future developments.

Nowadays diabetes, especially type 2 diabetes (which is strongly related to the Western diet and life-style), has developed worldwide into an epidemic disease. Nanomedicine aims to provide novel tools for diagnosis, therapy and point-of-care management of patients. Several nanotechnological approaches were developed to improve life quality for patients with insulin-dependent diabetes. They facilitate blood glucose management by non-invasive glucose measurement as well as insulin administration mainly by delivering the fragile protein as protected and targeted formulation via nasal or oral route. In the present review the oral or nasal insulin delivery by polymeric nanoparticles is discussed with focus on physiological change either related to the disease, diabetes or age-related metabolic variations influencing insulin release and bioavailability. One critical point is that new generations of targeted nanoparticle based drugs are developed and optimized for certain metabolic conditions. These conditions may change with age or disease. The influence of age-related factors such as immaturity in very young age, metabolic and physiologic changes in old age or insufficient animal models are still under-investigated not only in nanomedicine but also generally in pharmacology. Summarizing it can be noted that the bioavailability of insulin administered via routes others than subcutaneously is comparably low (max. 60%). Moreover factors like changed gut permeability as described for diabetes type 1 or other metabolic peculiarities such as insulin resistance in case of type 2 diabetes also play a role in affecting the development of novel nanoparticulated drug preparations and can be responsible for unsuccessful translation of promising animal results into human therapy. In future insulin nanoparticle development for diabetes must consider not only requirements imposed by the drug but also metabolic changes inflicted by disease or by age. Moreover new approaches are required for prevention of the disease.

The spider effect: morphological and orienting classification of microglia in response to stimuli in vivo.

The different morphological stages of microglial activation have not yet been described in detail. We transected the olfactory bulb of rats and examined the activation of the microglial system histologically. Six stages of bidirectional microglial activation (A) and deactivation (R) were observed: from stage 1A to 6A, the cell body size increased, the cell process number decreased, and the cell processes retracted and thickened, orienting toward the direction of the injury site; until stage 6A, when all processes disappeared. In contrast, in deactivation stages 6R to 1R, the microglia returned to the original site exhibiting a stepwise retransformation to the original morphology. Thin highly branched processes re-formed in stage 1R, similar to those in stage 1A. This reverse transformation mirrored the forward transformation except in stages 6R to 1R: cells showed multiple nuclei which were slowly absorbed. Our findings support a morphologically defined stepwise activation and deactivation of microglia cells.

Nanomedicine for treatment of diabetes in an aging population: state-of-the-art and future developments.

Nowadays diabetes, especially type 2 diabetes (which is strongly related to the Western diet and life-style), has developed worldwide into an epidemic disease. Nanomedicine aims to provide novel tools for diagnosis, therapy and point-of-care management of patients. Several nanotechnological approaches were developed to improve life quality for patients with insulin-dependent diabetes. They facilitate blood glucose management by non-invasive glucose measurement as well as insulin administration mainly by delivering the fragile protein as protected and targeted formulation via nasal or oral route. In the present review the oral or nasal insulin delivery by polymeric nanoparticles is discussed with focus on physiological change either related to the disease, diabetes or age-related metabolic variations influencing insulin release and bioavailability. One critical point is that new generations of targeted nanoparticle based drugs are developed and optimized for certain metabolic conditions. These conditions may change with age or disease. The influence of age-related factors such as immaturity in very young age, metabolic and physiologic changes in old age or insufficient animal models are still under-investigated not only in nanomedicine but also generally in pharmacology. Summarizing it can be noted that the bioavailability of insulin administered via routes others than subcutaneously is comparably low (max. 60%). Moreover factors like changed gut permeability as described for diabetes type 1 or other metabolic peculiarities such as insulin resistance in case of type 2 diabetes also play a role in affecting the development of novel nanoparticulated drug preparations and can be responsible for unsuccessful translation of promising animal results into human therapy. In future insulin nanoparticle development for diabetes must consider not only requirements imposed by the drug but also metabolic changes inflicted by disease or by age. Moreover new approaches are required for prevention of the disease.

Factorial analysis of adaptable properties of self-assembling peptide matrix on cellular proliferation and neuronal differentiation of pluripotent embryonic carcinoma.

An integrative and quantitative approach for systematically studying the effects of changing the matrix environment on pluripotent cell viability and neuronal differentiation was demonstrated. This approach, based on factorial analysis and a self-assembling peptide (SAP) matrix, was exemplified using P19 as a pluripotent cell model. In a two-level, three-factor factorial design of experiments, three niche factors, namely, culture dimensionality, fixed biochemical signal and mechanical stiffness, were simultaneously investigated. We found that cell growth was slowed in matrices containing IKVAV epitopes on the SAP constructs, and neuronal differentiation was promoted synergistically by culturing in a three-dimensional matrix and in the presence of IKVAV. Variation of the storage modulus from around 262 Pa to 672 Pa had no significant effect on either viability or differentiation. This approach should be applicable to studying how niche properties that are tunable using SAPs affect the behavior of pluripotent cells in general, thus generating guidelines for constructing artificial matrices. FROM THE CLINICAL EDITOR: In this basic science study, an integrative and quantitative approach to study the effects of matrix environment on pluripotent cell viability and neuronal differentiation is demonstrated. Approaches, like the one described in this paper, are applicable to studying how self assembling peptides affect the behavior of pluripotent cells in general.

Peptide amphiphiles and porous biodegradable scaffolds for tissue regeneration in the brain and spinal cord.

Many promising strategies have been developed for controlling the release of drugs from scaffolds, yet there are still challenges that need to be addressed in order for these scaffolds to serve as successful treatments. The RADA4 self-assembling peptide spontaneously forms nanofibers, creating a scaffold-like tissue-bridging structure that provides a three-dimensional environment for the migration of living cells. We have found that RADA4: (1) facilitates the regeneration of axons in the brain of young and adult hamsters, leading to functional return of behavior and (2) demonstrates robust migration of host cells and growth of blood vessels and axons, leading to the repair of injured spinal cords in rats.

Using self-assembled nanomaterials to inhibit the formation of metastatic cancer stem cell colonies in vitro.

The isolation of cells with stem-like properties from prostate tumors suggests the presence of a cancer stem cell (CSC) population, which may account for the initiation, progression, and metastasis as well as drug resistance of the disease. We hypothesized that containing, or at least immobilizing, the CSCs in a nano-self-assembling material might help prevent prostate tumor progression or metastasis. CSCs were plated in three conditions: 1) placed in 1% concentration self-assembled peptide (SAP) preequilibrate with culture medium; 2) placed in 3% concentration SAP preequilibrate with culture medium; and 3) in nonadherent culture. All were grown for 14 days, after which the cells in both 1% and 3% concentrations were washed out of the SAP and grown for an additional 14 days. Here we report that CSCs from prostate cancer cell lines remained quiescent for more than 28 days when embedded in SAP. When the prostate CSCs were embedded in 1% and 3% SAP, most of the CSCs remained single cells 14 days after plating in a nonadherent plate; no prostaspheres could be detected 14 days after plating, suggesting that self-renewal was significantly suppressed. In the controls, prostate CSCs began to divide 1 day after plating in a nonadherent plate and prostaspheres were visible at day 10, indicating the active self-renewal property of the prostate CSCs. Our findings suggest that SAP can completely inhibit a prostate CSC from self-renewal while preserving its viability and CSC property. Therefore, SAP may be an effective nanomaterial for inhibiting cancer progression and metastasis to stop the progression during treatment and removal.

At the nanoscale: nanohemostat, a new class of hemostatic agent.

Three basic categories of hemostats are widely used in surgery today: chemical agents, thermal devices, and mechanical methods that use pressure or ligature to slow bleeding. Each has its benefits and limitations. However, nanotechnology is rapidly ushering in new medical technologies. This review focuses on the 'nanohemostat', a new class of hemostatic agent that stops bleeding in less than 15 seconds by using (RADA)4, referred to as nanohemostat-1 (NHS-1), a synthetic biological material that self-assembles at the nanoscale when applied to a wound, and compares it to the characteristics of the 'ideal hemostat'.

Redefining tissue engineering for nanomedicine in ophthalmology.

Working at the nanoscale means to completely rethink how to approach engineering in the body in general and in the eye in particular. In nanomedicine, tissue engineering is the ability to influence an environment either by adding, subtracting or manipulating that environment to allow it to be more conducive for its purpose. The goal is to function at the optimum state, or to return to that optimum state. Additive tissue engineering replaces cells or tissue, or tries to get something to grow that is no longer there. Arrestive tissue engineering tries to stop aberrant growth which, if left uncontrolled, would result in a decrease in function. Nano delivery of therapeutics can perform both additive and arrestive functions influencing the environment either way, depending on the targeting. By manipulating the environment at the nanoscale, the rate and distribution of healing can be controlled. It infers that potential applications of nanomedicine in ophthalmology include procedures, such as corneal endothelial cell transplantation, single retinal ganglion cell repair, check of retinal ganglion cell viability, building of nanofibre scaffolds, such as self-assembling peptides, to create a scaffold-like tissue-bridging structure to provide a framework for axonal regeneration in the case of optic nerve reconnection or eye transplantation, and ocular drug delivery. Examples of potential arrestive therapies include gene-related treatment modalities to inhibit intraocular neovascularization and to block retinal cell apoptosis. Looking towards the future, this review focuses on how nanoscale tissue engineering can be and is being used to influence that local environment.

CNS regeneration after chronic injury using a self-assembled nanomaterial and MEMRI for real-time in vivo monitoring.

To speed up the process of central nervous system (CNS) recovery after injury, the need for real-time measurement of axon regeneration in vivo is essential to assess the extent of injury, as well as the optimal timing and delivery of therapeutics and rehabilitation. It was necessary to develop a chronic animal model with an in vivo measurement technique to provide a real-time monitoring and feedback system. Using the framework of the 4 P's of CNS regeneration (Preserve, Permit, Promote and Plasticity) as a guide, combined with noninvasive manganese-enhanced magnetic resonance imaging (MEMRI), we show a successful chronic injury model to measure CNS regeneration, combined with an in vivo measurement system to provide real-time feedback during every stage of the regeneration process. We also show that a chronic optic tract (OT) lesion is able to heal, and axons are able to regenerate, when treated with a self-assembling nanofiber peptide scaffold (SAPNS). FROM THE CLINICAL EDITOR: The authors of this study demonstrate the development of a chronic injury model to measure CNS regeneration, combined with an in vivo measurement system to provide real-time feedback during every stage of the regeneration process. In addition, they determined that chronic optic tract lesions are able to heal with axonal regeneration when treated with a self-assembling nanofiber peptide scaffold (SAPNS).

Ultrasound-enhanced intrascleral delivery of protein.

We aim to investigate ultrasound on enhancing protein penetration into the sclera, a non-invasive method to overcome the first barrier in taking the transscleral route for delivering therapeutics. Rabbit eyes were immersed in a fluorescein isothiocyanate conjugated bovine serum albumin solution. The distances of protein penetration, with and without ultrasound (30s continuous wave, 1MHz, 0.05W/cm(2)) applied on the sclera, and at different immersion time intervals (0, 5, 15, 30 and 60min), were measured by examining the cryo-sectioned tissues under fluorescence microscope (≥60 measurements from 3 eyes for each condition). Retina was examined for structural damage by histology. It was found that ultrasound enhances the intrascleral penetration of protein, increasing the diffusivity by 1.6-folds while causing no damage to the retinal tissues. This physical modulation of the sclera is temporary, as evident by the restoration of the diffusional resistance at 15min after ultrasound treatment. The negligible effect of ultrasound-induced convection and the minimal temperature rise (<0.5°C), together with cavitation detected by acoustic emission and a decreased penetration distance at higher ultrasound frequency (30s continuous wave, 3MHz, 0.05W/cm(2)), suggest that cavitation is a possible mechanism for increasing the permeability of the sclera for diffusive transport.

Resequencing microarray for detection of human adenoviruses in patients with conjunctivitis.

BACKGROUND: Although high-density resequencing microarray is useful for detection and tracking the evolution of viruses associated with respiratory tract infections, no report on using this technology for the detection of viruses in patients with conjunctivitis is available. OBJECTIVES: To test if high-density resequencing microarray can be applied to detection of viruses in conjunctival swabs for patients with conjunctivitis. STUDY DESIGN: In this prospective proof-of-concept study, every 4 or 5 bacterial culture-negative conjunctival swab samples were pooled and subject to viral detection using TessArray Resequencing Pathogen Microarrays-Flu 3.1 (RPM-Flu-3.1). Results were compared with human adenovirus (HAdV) hexon gene PCR sequencing and viral culture. RESULTS: Thirty-two of the 38 conjunctival swab samples were bacterial culture-negative. Four of the 7 pooled samples were positive for HAdV using RPM-Flu-3.1. Hexon gene PCR sequencing on the 38 original individual samples showed that 3 and 4 samples contained HAdVs species D and B respectively. All the 6 samples that were positive for hexon gene PCR but negative for bacterial culture were also positive by the resequencing microarray. Viral culture was positive for HAdV type 3 in 1 sample, which was also positive by PCR and resequencing microarray. CONCLUSIONS: Resequencing microarray is as sensitive as PCR for detection of HAdV in conjunctival swabs. Unlike viral culture and hexon gene PCR sequencing, resequencing microarray was not able to differentiate the type and species of HAdV. Development of microarrays for conjunctivitis can be performed for rapid diagnosis of the viral cause of conjunctivitis.

Visual response properties of Y cells in the detached feline retina.

PURPOSE: To evaluate early changes in the visual response properties of Y cells in the detached feline retina. METHODS: The retinas of young adult cats were detached by injection, with a glass micropipette, of a solution of 0.004% sodium hyaluronate in a balanced salt solution between the neural retina and the retinal pigment epithelium. At 1, 3, and 7 days after detachment, the eyes were removed. The eyecup was prepared as a flat mount in a recording chamber and superfused with medium. Extracellular single-unit responses from Y cells in the retinas were recorded. RESULTS: One, 3, and 7 days after retinal detachment surgery, Y cells showed clear signs of functional deterioration. At each time point, more ON center cells than OFF cells were encountered. Y cells in the detached retinas showed a statistically significant elevation in the average threshold irradiance after 1-, 3-, and 7-day detachment, respectively. The average contrast threshold recorded from cells in the normal retina was 3.6%, but it increased to 14.5%, 21.8%, and 47.5% after 1-, 3-, and 7-day detachment, respectively. Furthermore, at each time point, the capability of Y cells to process contrast information decreased significantly more because of detachment than because of luminance task performance. CONCLUSIONS: Retinal detachment induced rapid functional remodeling that resulted in degenerated Y-cell function, including an elevated luminance threshold and a deteriorated contrast threshold. Detachment had a greater impact on the latter. These physiological changes after retinal detachment could be used as objective indicators of early deterioration of visual function in future studies of retinal remodeling.