Rasagiline Exerts Neuroprotection towards Oxygen-Glucose-Deprivation/Reoxygenation-Induced GAPDH-Mediated Cell Death by Activating Akt/Nrf2 Signaling.

Rasagiline (Azilect®) is a selective monoamine oxidase B (MAO-B) inhibitor that provides symptomatic benefits in Parkinson's disease (PD) treatment and has been found to exert preclinical neuroprotective effects. Here, we investigated the neuroprotective signaling pathways of acute rasagiline treatment for 22 h in PC12 neuronal cultures exposed to oxygen-glucose deprivation (OGD) for 4 h, followed by 18 h of reoxygenation (R), causing 40% aponecrotic cell death. In this study, 3-10 µM rasagiline induced dose-dependent neuroprotection of 20-80%, reduced the production of the neurotoxic reactive oxygen species by 15%, and reduced the nuclear translocation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) by 75-90%. In addition, 10 µM rasagiline increased protein kinase B (Akt) phosphorylation by 50% and decreased the protein expression of the ischemia-induced α-synuclein protein by 50% in correlation with the neuroprotective effect. Treatment with 1-5 µM rasagiline induced nuclear shuttling of transcription factor Nrf2 by 40-90% and increased the mRNA levels of the antioxidant enzymes heme oxygenase-1, (NAD (P) H- quinone dehydrogenase, and catalase by 1.8-2.0-fold compared to OGD/R insult. These results indicate that rasagiline provides neuroprotection to the ischemic neuronal cultures through the inhibition of α-synuclein and GAPDH-mediated aponecrotic cell death, as well as via mitochondrial protection, by increasing mitochondria-specific antioxidant enzymes through a mechanism involving the Akt/Nrf2 redox-signaling pathway. These findings may be exploited for neuroprotective drug development in PD and stroke therapy.

Revascularization of decellularized lung scaffolds: principles and progress.

There is a clear unmet clinical need for novel biotechnology-based therapeutic approaches to lung repair and/or replacement, such as tissue engineering of whole bioengineered lungs. Recent studies have demonstrated the feasibility of decellularizing the whole organ by removal of all its cellular components, thus leaving behind the extracellular matrix as a complex three-dimensional (3D) biomimetic scaffold. Implantation of decellularized lung scaffolds (DLS), which were recellularized with patient-specific lung (progenitor) cells, is deemed the ultimate alternative to lung transplantation. Preclinical studies demonstrated that, upon implantation in rodent models, bioengineered lungs that were recellularized with airway and vascular cells were capable of gas exchange for up to 14 days. However, the long-term applicability of this concept is thwarted in part by the failure of current approaches to reconstruct a physiologically functional, quiescent endothelium lining the entire vascular tree of reseeded lung scaffolds, as inferred from the occurrence of hemorrhage into the airway compartment and thrombosis in the vasculature in vivo. In this review, we explore the idea that successful whole lung bioengineering will critically depend on 1) preserving and/or reestablishing the integrity of the subendothelial basement membrane, especially of the ultrathin respiratory membrane separating airways and capillaries, during and following decellularization and 2) restoring vascular physiological functionality including the barrier function and quiescence of the endothelial lining following reseeding of the vascular compartment. We posit that physiological reconstitution of the pulmonary vascular tree in its entirety will significantly promote the clinical translation of the next generation of bioengineered whole lungs.

Mesenchymal stem cells for therapeutic applications in pulmonary medicine.

INTRODUCTION: Mesenchymal stem cells (MSCs) of different biological sources are in Phase 1 clinical trials and are being considered for Phase 2 therapy of lung disorders, and lung (progenitor) cells derived from pluripotent stem cells (SCs) are under development in preclinical animal models. SOURCES OF DATA: PubMed.gov and ClinicalTrials.gov. AREAS OF AGREEMENT: There is consensus about the therapeutic potential of transplanted SCs, mainly MSCs, primarily involves paracrine 'bystander' effects that confer protection of the epithelial and endothelial linings of the lung caused by inflammation and/or fibrosis and lead to increased survival in animal models. Clinical trials of Phase 1 indicate safety and suggest that the efficacy of SC therapy in patients with various lung diseases will require a higher dosage than previously evaluated. AREAS OF CONTROVERSY: A growing interest in the re-epithelialization and re-endothelialization of damaged lung tissue involves the putative pulmonary differentiation of exogenous MSCs. Currently, it is not clear whether or not the observed regeneration of distal airways/vasculature is derived from lung-resident and/or transplanted SCs. GROWING POINTS: Important topics under investigation include optimization of the cell source with a decrease in cell population heterogeneity characterized by defined markers, route of delivery for effective treatment, potential dose and therapeutic protocol of SC application, development of quantitative assays and biomarkers of lung disease and repair, and the potential use of tissue engineered lung. AREAS TIMELY FOR DEVELOPING RESEARCH: Ability of MSCs to differentiate into epithelial cells of the lung, use of autologous induced pluripotent SCs (iPSCs) derived from the patients, complete biochemical characterization of the secretome of SCs used for therapy, and the incorporation of simultaneous and/or subsequent treatment with drugs which also aid in lung repair and regeneration. CAUTIONARY NOTE: Although safety of MSC-based cell therapy was proved in Phase 1, efficacy, long-term survival and preservation of lung respiratory function need to be further evaluated, cautioning against hastily translating SCs therapy from animal models of lung injury to clinical trials of patients with lung disorders.

Association of p75(NTR) and α9ß1 integrin modulates NGF-dependent cellular responses.

Direct interaction of α9ß1 integrin with nerve growth factor (NGF) has been previously reported to induce pro-proliferative and pro-survival activities of non-neuronal cells. We investigated participation of p75(NTR) in α9ß1 integrin-dependent cellular response to NGF stimulation. Using selective transfection of glioma cell lines with these receptors, we showed a strong, cation-independent association of α9 integrin subunit with p75(NTR) on the cellular membrane by selective immunoprecipitation experiments. The presence of the α9/p75(NTR) complex increases NGF-dependent cell adhesion, proliferation and migration. Other integrin subunits including ß1 were not found in complex with p75(NTR). FRET analysis indicated that p75(NTR) and α9 integrin subunit are not closely associated through their cytoplasmic domains, most probably because of the molecular interference with other cytoplasmic proteins such as paxillin. Interaction of α9ß1 integrin with another ligand, VCAM-1 was not modulated by the p75(NTR). α9/p75(NTR) complex elevated NGF-dependent activation of MAPK Erk1/2 arty for integrin that may create active complexes with other types of receptors belonging to the TNF superfamily.

Anti-angiogenic activities of snake venom CRISP isolated from Echis carinatus sochureki.

BACKGROUND: Cysteine-rich secretory protein (CRISP) is present in majority of vertebrate including human. The physiological role of this protein is not characterized. We report that a CRISP isolated from Echis carinatus sochureki venom (ES-CRISP) inhibits angiogenesis. METHODS: The anti-angiogenic activity of purified ES-CRISP from snake venom was investigated in vitro using endothelial cells assays such as proliferation, migration and tube formation in Matrigel, as well as in vivo in quail embryonic CAM system. The modulatory effect of ES-CRISP on the expression of major angiogenesis factors and activation of angiogenesis pathways was tested by qRT-PCR and Western blot. RESULTS: The amino acid sequence of ES-CRISP was found highly similar to other members of this snake venom protein family, and shares over 50% identity with human CRISP-3. ES-CRISP supported adhesion to endothelial cells, although it was also internalized into the cytoplasm in a granule-like manner. It blocked EC proliferation, migration and tube formation in Matrigel. In the embryonic quail CAM system, ES-CRISP abolished neovascularization process induced by exogenous growth factors (bFGF, vpVEGF) and by developing gliomas. CRISP modulates the expression of several factors at the mRNA level, which were characterized as regulators of angiogenesis and blocked activation of MAPK Erk1/2 induced by VEGF. CONCLUSIONS: ES-CRISP was characterized as a negative regulator of the angiogenesis, by direct interaction with endothelial cells. GENERAL SIGNIFICANCE: The presented work may lead to the development of novel angiostatic therapy, as well as contribute to the identification of the physiological relevance of this functionally uncharacterized protein.

Hypoxia enhances differentiation of mouse embryonic stem cells into definitive endoderm and distal lung cells.

We investigated the effects of hypoxia on spontaneous (SP)- and activin A (AA)-induced definitive endoderm (DE) differentiation of mouse embryonic stem cells (mESCs) and their subsequent differentiation into distal pulmonary epithelial cells. SP differentiation for 6 days of mESCs toward endoderm at hypoxia of 1% O2, but not at 3% or 21% (normoxia), increased the expression of Sox17 and Foxa2 by 31- and 63-fold above maintenance culture, respectively. Treatment of mESCs with 20 ng/mL AA for 6 days under hypoxia further increased the expression of DE marker genes Sox17, Foxa2, and Cxcr4 by 501-, 1,483-, and 126-fold above maintenance cultures, respectively. Transient exposure to hypoxia, as short as 24 h, was sufficient to enhance AA-induced endoderm formation. The involvement of hypoxia-inducible factor (HIF)-1α and reactive oxygen species (ROS) in the AA-induced endoderm enrichment was assessed using HIF-1α(-/-) mESCs and the ROS scavenger N-acetylcysteine (NAC). Under SP conditions, HIF-1α(-/-) mESCs failed to increase the expression of endodermal marker genes but rather shifted toward ectoderm. Hypoxia induced only a marginal potentiation of AA-induced endoderm differentiation in HIF-1α(-/-) mESCs. Treatment of mESCs with AA and NAC led to a dose-dependent decrease in Sox17 and Foxa2 expression. In addition, the duration of exposure to hypoxia in the course of a recently reported lung differentiation protocol resulted in differentially enhanced expression of distal lung epithelial cell marker genes aquaporin 5 (Aqp5), surfactant protein C (Sftpc), and secretoglobin 1a1 (Scgb1a1) for alveolar epithelium type I, type II, and club cells, respectively. Our study is the first to show the effects of in vitro hypoxia on efficient formation of DE and lung lineages. We suggest that the extent of hypoxia and careful timing may be important components of in vitro differentiation bioprocesses for the differential generation of distal lung epithelial cells from pluripotent progenitors.

Transcriptional down-regulation of epidermal growth factor (EGF) receptors by nerve growth factor (NGF) in PC12 cells.

Nerve growth factor (NGF) treatment causes a profound down-regulation of epidermal growth factor (EGF) receptors (EGFR) during the neuronal differentiation of PC12 cells. This process was characterized by a progressive decrease in EGFR level, as measured by (125)I-EGF binding and Scatchard analysis, tyrosine phosphorylation, Western blotting, and bio-imaging using EGF-labeled with a near-infrared probe. Differentiation of the cells with NGF for 5-7 days produces a 95 % reduction in the amount of (35)S-methionine-labeled EGFR. This down-regulation does not occur in PC12-nnr5 cells, which lack the TrkA NGF receptor but is reconstituted in these cells upon their stable transfection with TrkA. The process of NGF-induced EGFR down-regulation was inhibited by K252a, a TrkA antagonist and by anti-TrkA antibodies but not by Thx-B, a blocker of the interaction of NGF with p75(NTR) receptors. NGF-induced (heterologous) down-regulation, but not EGF-induced (homologous) down-regulation of EGFR, was blocked in Ras-deficient PC12 cells. NGF treatment for 5-7 days of PC12 cells, grown in suspension or in 3D collagen gels, induces down-regulation of EGFR independent of neurite outgrowth. The messenger RNA (mRNA) for EGFR decreased in a comparable fashion. This process was correlated temporally with a decrease in the transcription of the EGFR gene. Treatment with NGF also increased the cellular content of GCF2, a putative inhibitory transcription factor of the EGFR gene. The temporal increase in GCF2, like the decrease in the EGFR mRNA, was not seen in TrkA deficient PC12 cells nor in cells expressing dominant-negative Ras. The results suggest that NGF-induced down-regulation of the EGFR is under transcriptional control, is TrkA and Ras-dependent, may involve transcriptional repression by GCF2, and independent of mechanisms that lead to NGF-induced neurite outgrowth in PC12cells. This heterologous down-regulation of EGFR would appear to be an efficient mean of desensitizing the neuron to proliferative stimuli, thereby representing a safety latch for initiating and sustaining NGF-induced neuronal differentiation.

Heterogeneous mixed-lineage differentiation of mouse embryonic stem cells induced by conditioned media from a549 cells.

Conditioned media (CM) of transformed cells, such as the human lung-derived A549 cells, is a useful tool for directing differentiation of embryonic stem cells (ESCs). Previous work indicates that A549-CM induced pulmonary differentiation of mouse ESCs (mESCs). In this study, we compared the effects of A549-CM treatment on the differentiation of mESCs organized in monolayer or embryoid bodies. We analyzed the cultures treated with A549-CM using specific lineage markers by quantitative polymerase chain reaction (qPCR) and lineage-focused PCR arrays and demonstrated heterogeneous CM-induced differentiation. We then constructed bioinformatics-based gene networks to establish correlations between the upregulated lineage-specific genes and proteins in the A549-CM identified by proteomic analysis. Network analysis supported the phenotypic and genotypic heterogeneic differentiation of mESCs into multiple cell lineages via enriched stemness, cardiovascular, neuronal, and lung development gene ontologies (GOs). The significant enrichment toward lung ontologies was specific for treatment with A549-CM, but not CM of liver (HepG2) and pancreas (Capan-1) cells. Based on network analysis, we identified laminin alpha5, prosaposin, lamin A/C, dickkopf homolog 1, clusterin, and calreticulin as the most relevant proteins related to the enrichment of lung GOs. We validated the effects of laminin isoforms on mESC differentiation in vitro and found enriched differential induction of surfactant protein gene expression. Our data suggest that A549-CM can be used for identifying secreted proteins for the heterogeneous mixed-lineage differentiation of mESCs toward a variety of lung-relevant cells. Such a heterogeneous cell population will be required for the in vitro generation of complex lung tissue and mixed cell populations for regenerative pulmonary therapy.

Cytocompatibility of novel extracellular matrix protein analogs of biodegradable polyester polymers derived from α-hydroxy amino acids.

One of the challenges in regenerative medicine is the development of novel biodegradable materials to build scaffolds that will support multiple cell types for tissue engineering. Here we describe the preparation, characterization, and cytocompatibility of homo- and hetero-polyesters of α-hydroxy amino acid derivatives with or without lactic acid conjugation. The polymers were prepared by a direct condensation method and characterized using gel permeation chromatography, (1)H-nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, optical activity, and solubility. The surface charge of the polymers was evaluated using zeta potential measurements. The polymers were coated onto glass cover slips followed by characterization using nano-surface profiler, thin film reflectometry, and atomic force microscopy (AFM). Their interaction with endothelial and neuronal cells was assessed using adhesion, proliferation, and differentiation assays. Of the characterized polymers, Poly-HOVal-LA, but not Poly-(D)HOPhe, significantly augmented nerve growth factor (NGF)-induced neuronal differentiation of the PC12 pheochromcytoma cells. In contrast, Poly-HOLeu increased by 20% the adhesion of endothelial cells, but did not affect PC12 cell differentiation. NGF-induced Erk1/2 phosphorylation in PC12 cells grown on the different polymers was similar to the effect observed for cells cultured on collagen type I. While no significant association could be established between charge and the differentiative/proliferative properties of the polymers, AFM analysis indicated augmentation of NGF-induced neuronal differentiation on smooth polymer surfaces. We conclude that overall selective cytocompatibility and bioactivity might render α-hydroxy amino acid polymers useful as extracellular matrix-mimicking materials for tissue engineering.

Enhanced reseeding of decellularized rodent lungs with mouse embryonic stem cells.

Repopulation of decellularized lung scaffolds (DLS) is limited due to alterations in the repertoire and ratios of the residual extracellular matrix (ECM) proteins, characterized by e.g., the retention of type I collagen and loss of glycoproteins. We hypothesized that pre-treatment of decellularized matrices with defined ECM proteins, which match the repertoire of integrin receptors expressed by the cells to be seeded (e.g., embryonic stem cells) can increase the efficacy of the reseeding process. To test this hypothesis, we first determined the integrin receptors profile of mouse embryonic stem cells (mESCs). Mouse ESCs express α3, α5, α6, α9 and ß1, but not α1, α2 and α4 integrin subunits, as established by Western blotting and adhesion to laminin and fibronectin, but not to collagens type I and IV. Reseeding of DLS with mESCs was inefficient (6.9 ± 0.5%), but was significantly enhanced (2.3 ± 0.1 fold) by pre-treating the scaffolds with media conditioned by A549 human lung adenocarcinoma cells, which we found to contain ∼5 µg/ml laminin. Furthermore, pre-treatment with A549-conditioned media resulted in a significantly more uniform distribution of the seeded mESCs throughout the engineered organ as compared to untreated DLS. Our study may advance whole lung engineering by stressing the importance of matching the integrin receptor repertoire of the seeded cells and the cell binding motifs of DLS.

Near infrared optical visualization of epidermal growth factor receptors levels in COLO205 colorectal cell line, orthotopic tumor in mice and human biopsies.

In this study, we present the applicability of imaging epidermal growth factor (EGF) receptor levels in preclinical models of COLO205 carcinoma cells in vitro, mice with orthotopic tumors and ex vivo colorectal tumor biopsies, using EGF-labeled with IRDye800CW (EGF-NIR). The near infrared (NIR) bio-imaging of COLO205 cultures indicated specific and selective binding, reflecting EGF receptors levels. In vivo imaging of tumors in mice showed that the highest signal/background ratio between tumor and adjacent tissue was achieved 48 hours post-injection. Dissected colorectal cancer tissues from different patients demonstrated ex vivo specific imaging using the NIR bio-imaging platform of the heterogeneous distributed EGF receptors. Moreover, in the adjacent gastrointestinal tissue of the same patients, which by Western blotting was demonstrated as EGF receptor negative, no labeling with EGF-NIR probe was detected. Present results support the concept of tumor imaging by measuring EGF receptor levels using EGF-NIR probe. This platform is advantageous for EGF receptor bio-imaging of the NCI-60 recommended panel of tumor cell lines including 6-9 colorectal cell lines, since it avoids radioactive probes and is appropriate for use in the clinical setting using NIR technologies in a real-time manner.

NGF promotes hemodynamic recovery in a rabbit hindlimb ischemic model through trkA- and VEGFR2-dependent pathways.

Nerve growth factor (NGF) has been reported to play an important role in physiological and pathological angiogenesis. Based on these observations, we hypothesized that NGF may induce the formation of functional blood vessels in a hindlimb ischemic rabbit model. Hindlimb ischemia was induced in 34 rabbits bilaterally by endovascular embolization of femoral arteries. On the 7th, 14th, and 20th postembolization days, NGF was injected intramuscularly, in 1 ischemic limb, and vehicle was injected in the contralateral control limb. On the 40th day, newly developed collateral vessels (diameter >500 µm) were quantified by transauricular intraarterial subtraction angiography. Perfusion analysis of an in vivo dynamic computed tomography study was performed to the limbs to investigate the hemodynamic recovery of the distal ischemic tissues. Functional estimation of limb perfusion showed a statistically significant increase of blood flow and blood volume for NGF. However, the increase of the collateral vessels was not detectable angiographically, providing evidence for the existence of a NGF-stimulated capillary angiogenic network but not increase of arteriogenesis. The combination of NGF with either tropomyosin-related kinase type A or vascular endothelial growth factor receptor 2 antagonists abolished the NGF-induced hemodynamic recovery. These findings provide new insights into understanding the involvement of NGF in vascular formation and its applications in therapeutic angiogenesis.

Nerve growth factor reduces myocardial ischemia/reperfusion injury in rat hearts.

BACKGROUND: Nerve growth factor (NGF) is a neurotrophin that supports the survival and differentiation of sympathetic neurons, and its increased expression after myocardial infarct was correlated with cardiac sympathetic hyperinnervation and arrhythmias. However, it is unclear whether NGF protects the heart during infarct. In this study, we sought to address this issue in rat heart exposed to ischemia/reperfusion injury (IRI). METHODS: NGF was administered intravenously (IV), 15 min before ischemia, at different concentrations in the absence or presence of inhibitors of phosphatidylinositol-3 kinase (PI3K) or nitric oxide synthase (NOS) in different groups of rats (n=6) with left coronary occlusion for 30 min followed by 120-min reperfusion. The area at risk and infarct to risk ratios were determined from sections stained with 1% 2,3,5-triphenylterazolium chloride. RESULTS: NGF treatment at doses of 0.015-15 µg/kg, with an optimal dose of 0.15 µg/kg given IV before ischemia, reduced the infarct size from about 60% at the area of risk to about 25%, indicating cardioprotection by about 60%. The infarct-sparing effects of NGF were partially abolished by the inhibition of PI3K and NOS using wortmannin and N(G)-monomethyl-l-arginine, respectively. CONCLUSIONS: We have demonstrated for the first time that NGF attenuates myocardial infarct damage in an in vivo rat model of myocardial regional IRI. This cardioprotective effect is proposed to be related to the activities of PI3K and NOS. This suggests that NGF has a potential therapeutic role in the treatment of IRI.

Enhanced survival and neurite network formation of human umbilical cord blood neuronal progenitors in three-dimensional collagen constructs.

Umbilical cord blood (CB) stem cells have been proposed for cell-based therapeutic applications for diverse diseases of the CNS. We hypothesized that tissue-engineering strategies may extend the efficacy of these approaches by improving the long-term viability and function of stem cell-derived neuronal progenitors. To test our hypothesis, we explored the survival and differentiation of human CB-derived neuronal progenitors (HUCBNP) in a three-dimensional (3D) collagen construct. In contrast to two-dimensional culture conditions, the cells survived in 3D for an extended period of time of more than 2 months. Under 3D conditions, HUCBNP underwent spontaneous neuronal differentiation, which was further enhanced by treatment with neuronal conditioned medium (CM) and nerve growth factor (NGF). Neurite outgrowth, quantified by assessing the fractal dimension (D f) of the complex neuronal networks, was significantly enhanced under 3D conditions in the presence of CM/NGF, concomitant with a reduced expression of the early neuronal marker nestin (1.9-fold), and increased levels of mature neuronal markers such as MAP-2 (3.6-fold), ß-tubulin (1.5-fold), and neuronal specific enolase (6.6-fold) and the appearance of the synaptic marker synaptophysin. To assess the feasibility for clinical usage, HUCBNP were also isolated from frozen CB samples and cultured under 3D conditions. The data indicate the essential complete preservation of neurotrophic (survival) and neurotropic (neurite outgrowth) properties. In conclusion, 3D culture conditions are proposed as an essential step for both maintenance of CB neuronal progenitors in vitro and for investigating specific features of neuronal differentiation towards future use in regenerative therapy.

Bio-imaging of colorectal cancer models using near infrared labeled epidermal growth factor.

Novel strategies that target the epidermal growth factor receptor (EGFR) have led to the clinical development of monoclonal antibodies, which treat metastatic colorectal cancer (mCRC) but only subgroups of patients with increased wild type KRAS and EGFR gene copy, respond to these agents. Furthermore, resistance to EGFR blockade inevitably occurred, making future therapy difficult. Novel bio-imaging (BOI) methods may assist in quantization of EGFR in mCRC tissue thus complementing the immunohistochemistry methodology, in guiding the future treatment of these patients. The aim of the present study was to explore the usefulness of near infrared-labeled EGF (EGF-NIR) for bio-imaging of CRC using in vitro and in vivo orthotopic tumor CRC models and ex vivo human CRC tissues. We describe the preparation and characterization of EGF-NIR and investigate binding, using BOI of a panel of CRC cell culture models resembling heterogeneity of human CRC tissues. EGF-NIR was specifically and selectively bound by EGFR expressing CRC cells, the intensity of EGF-NIR signal to background ratio (SBR) reflected EGFR levels, dose-response and time course imaging experiments provided optimal conditions for quantization of EGFR levels by BOI. EGF-NIR imaging of mice with HT-29 orthotopic CRC tumor indicated that EGF-NIR is more slowly cleared from the tumor and the highest SBR between tumor and normal adjacent tissue was achieved two days post-injection. Furthermore, images of dissected tissues demonstrated accumulation of EGF-NIR in the tumor and liver. EGF-NIR specifically and strongly labeled EGFR positive human CRC tissues while adjacent CRC tissue and EGFR negative tissues expressed weak NIR signals. This study emphasizes the use of EGF-NIR for preclinical studies. Combined with other methods, EGF-NIR could provide an additional bio-imaging specific tool in the standardization of measurements of EGFR expression in CRC tissues.

Nerve growth factor stimulation of ERK1/2 phosphorylation requires both p75NTR and α9ß1 integrin and confers myoprotection towards ischemia in C2C12 skeletal muscle cell model.

The functions of nerve growth factor (NGF) in skeletal muscles physiology and pathology are not clear and call for an updated investigation. To achieve this goal we sought to investigate NGF-induced ERK1/2 phosphorylation and its role in the C2C12 skeletal muscle myoblasts and myotubes. RT-PCR and western blotting experiments demonstrated expression of p75(NTR), α9ß1 integrin, and its regulator ADAM12, but not trkA in the cells, as also found in gastrocnemius and quadriceps mice muscles. Both proNGF and ßNGF induced ERK1/2 phosphorylation, a process blocked by (a) the specific MEK inhibitor, PD98059; (b) VLO5, a MLD-disintegrin with relative selectivity towards α9ß1 integrin; and (c) p75(NTR) antagonists Thx-B and LM-24, but not the inactive control molecule backbone Thx. Upon treatment for 4 days with either anti-NGF antibody or VLO5 or Thx-B, the proliferation of myoblasts was decreased by 60-70%, 85-90% and 60-80% respectively, indicative of trophic effect of NGF which was autocrinically released by the cells. Exposure of myotubes to ischemic insult in the presence of ßNGF, added either 1h before oxygen-glucose-deprivation or concomitant with reoxygenation insults, resulted with about 20% and 33% myoprotection, an effect antagonized by VLO5 and Thx-B, further supporting the trophic role of NGF in C2C12 cells. Cumulatively, the present findings propose that proNGF and ßNGF-induced ERK1/2 phosphorylation in C2C12 cells by functional cooperation between p75(NTR) and α9ß1 integrin, which are involved in myoprotective effects of autocrine released NGF. Furthermore, the present study establishes an important trophic role of α9ß1 in NGF-induced signaling in skeletal muscle model, resembling the role of trkA in neurons. Future molecular characterization of the interactions between NGF receptors in the skeletal muscle will contribute to the understanding of NGF mechanism of action and may provide novel therapeutic targets.

Neuroprotective effects of nimodipine and nifedipine in the NGF-differentiated PC12 cells exposed to oxygen-glucose deprivation or trophic withdrawal.

The goal of this study was to compare the neuroprotective properties of the L-type Ca²âº channel blockers, nimodipine and nifedipine, using nerve growth factor (NGF)-differentiated PC12 neuronal cultures exposed to oxygen-glucose deprivation (OGD) and trophic withdrawal-induced cell death. Nimodipine (1-100 µM) conferred 65±13% neuroprotection upon exposure to OGD and 35±6% neuroprotection towards different trophic withdrawal-induced cell death measured by lactate dehydrogenase and caspase 3 activities. The time window of nimodipine conferred neuroprotection was detected during the first 5h but not at longer OGD exposures. Nifedipine (1-100 µM), to a lower potency than nimodipine, conferred 30-55±8% neuroprotection towards OGD in PC12 cells and 29±5% in rat hypocampal slices, and 10±3% neuroprotection at 100 µM towards trophic withdrawal-induced PC12 cell death. The ability to demonstrate that nimodipine conferred neuroprotection in a narrow therapeutic time-window indicates that the OGD PC12 model mimics the in vivo models and therefore suitable for neuroprotective drug discovery and development.

Neuroprotection by human umbilical cord blood-derived progenitors in ischemic brain injuries.

Stem cells have an extremely high potential to treat many devastating diseases, including neuronal injuries. Albeit the need for human neuronal stem cells, their quantities are very limited by relying on early human embryos as the main source. Therefore, progenitors of other origins, such as human umbilical cord blood (CB) are being considered. In the last decade, various populations isolated from the CB were reported to differentiate in vitro towards a neural phenotype. The conditions to induce the cell differentiation are not conclusive and may include addition of chemicals, cytokines and growth factors, including the nerve growth factor (NGF). Some CB cells were found to express the TrkANGF receptor, suggesting an endogenous role for this growth factor also in the CB environment. The ability of CB and derived stem cell populations to protect against neurological deficits was shown, both in vitro and in vivo, in models of ischemic brain injuries. In rodent models of stroke, heatstroke, brain trauma and brain damage at birth, CB cells either by intravenous injection or intrastriatal transplantation, were found to reduce the infarct size and the neurological deficits caused by the injury. The restorative effects of CB were suggested to be mediated by mechanisms other than cell replacement. Some of the proposed mechanisms involve reduced inflammation, nerve fiber reorganization by trophic actions, increased cell survival and enhanced angiogenesis. Furthermore, treatment with CB was found to have a therapeutic window of days compared with the present 36 hour window for the treatment of stroke with clinically available tools such as recombinant tissue plasminogen activator. Considering the encouraging results with whole CB and derived cells transplantation in ischemic injury models and since CB is widely available and have been used clinically, they may be an excellent source of cells for treatment of human brain ischemic disorders.

High plasma levels and effective lymphatic uptake of docetaxel in an orally available nanotransporter formulation.

Docetaxel, an efficient chemotherapeutic drug, exhibits low and variable oral bioavailability due to the active efflux by P-glycoprotein (P-gp) and more so to CYP3A4 gut metabolism. Using a spray-drying technique, docetaxel was incorporated in PLGA [poly(lactic-co-glycolic acid)] nanocapsules (NC) which were embedded in entero-coated microparticles. An oral administration of the NC formulation elicited a higher absolute bioavailability than both a docetaxel solution (276%) and a free docetaxel NC formulation (400%) injected intravenously, a 5-mg/kg dose. The batches (B) I and II NC formulations elicited C(max) values that were 1,735% and 2,254%, respectively; higher than the C(max) value of the oral docetaxel solution combined with blank microparticles, a 10-mg/kg dose. No significant difference in AUC (area under curve) was observed between the batches. These unexpected results can be explained only if the pharmacokinetics of docetaxel had been modified. It was shown that NCs released from the microparticles penetrated the enterocytes, bypassing P-gp; apparently circumventing gut metabolism and accumulating within the lymphatic system from where both intact or biodegraded NCs and free docetaxel were progressively released into the circulation as plausibly supported by the fluorescent imaging results. Furthermore, the circulating docetaxel in plasma was unencapsulated and circulated either in free form or bound to albumin. Both free docetaxel NCs and microparticles exhibited in vitro efficacy on WRC 256 cells suggesting that the activity of docetaxel was not altered. This delivery concept has potential for clinical translation, perhaps allowing docetaxel chemotherapy to be switched from intravenous to oral delivery.

Cetuximab-labeled liposomes containing near-infrared probe for in vivo imaging.

A new liposome-based near-infrared probe that combines both imaging and targeting abilities was developed for application in medical imaging. The near-infrared fluorescent molecule indocyanine green (ICG), and the cetuximab monoclonal antibody for epidermal growth factor receptor (EGFR) were attached to liposomes by passive adsorption. It was found that ICG molecules adsorbed to the liposomes are more fluorescent than free ICG and have a larger quantum yield. Cetuximab-adsorbed fluorescent liposomes preserved EGFR recognition, as is evident from internalization and selective binding to A431 colon carcinoma cells overexpressing EGFR. The binding of cetuximab-targeted fluorescent liposomes to A431 compared with IEC-6 cells (normal enterocytes expressing physiological EGFR levels) was greater by a factor of 3.5, ensuring imaging abilities with available fluorescent equipment. Due to relatively high quantum yield and specific tumor cell-recognizing ability, this technology deserves further in vivo evaluation for imaging and diagnostic purposes. FROM THE CLINICAL EDITOR: A new liposome-based near-infrared probe combining both imaging and targeting abilities is reported. Due to relatively high quantum yield and EGFR-expressing tumor cell specificity, this technology deserves further in vivo evaluation for imaging and diagnostic purposes.