Delivery Of NGF Research Articles

Intranasal delivery of NGF rescues hearing impairment in aged SAMP8 mice

Hearing loss impacts the quality of life and affects communication resulting in social isolation and reduced well-being. Despite its impact on society and economy, no therapies for age-related hearing loss are available so far. Loss of mechanosensory hair cells of the cochlea is a common event of hearing loss in humans. Studies performed in birds demonstrating that they can be replaced following the proliferation and transdifferentiation of supporting cells, strongly pointed out on HCs regeneration as the main focus of research aimed at hearing regeneration. Neurotrophins are growth factors involved in neuronal survival, development, differentiation, and plasticity. NGF has been involved in the interplay between auditory receptors and efferent innervation in the cochlea during development. During embryo development, both NGF and its receptors are highly expressed in the inner ears. It has been reported that NGF is implicated in the differentiation of auditory gangliar and hair cells. Thus, it has been proposed that NGF administration can decrease neuronal damage and prevent hearing loss. The main obstacle to the development of hearing impairment therapy is that efficient means of delivery for selected drugs to the cochlea are missing. Herein, in this study NGF was administered by the intranasal route. The first part of the study was focused on a biodistribution study, which showed the effective delivery in the cochlea; while the second part was focused on analyzing the potential therapeutic effect of NGF in senescence-accelerated prone strain 8 mice. Interestingly, intranasal administration of NGF resulted protective in counteracting hearing impairment in SAMP8 mice, ameliorating hearing performances (analyzed by auditory brainstem responses and distortion product otoacoustic emission) and hair cells morphology (analyzed by microscopy analysis). The results obtained were encouraging indicating that the neurotrophin NGF was efficiently delivered to the inner ear and that it was effective in counteracting hearing loss.

Bioactive 3D Scaffolds for the Delivery of NGF and BDNF to Improve Nerve Regeneration

Peripheral nerve injury is an important cause of disability, that can hinder significantly sensory and motor function. The clinical gold standard for peripheral nerve repair is the use of autografts, nevertheless, this method has limitations such as donor site morbidity. An emerging alternative to autografts are nerve guide conduits, which are used to entubulate the severed nerve and provide guidance for the directed regeneration of the nerve tissue. These nerve guide conduits are less effective than autografts, and to enhance their performance the incorporation of neurotrophins can be considered. To enable optimal nerve regeneration, it is important to continuously stimulate neurite outgrowth by designing a delivery system for the sustained delivery of neurotrophins. The aim of this study was to develop a novel bioactive surface on electrospun fibres to supply a sustained release of heparin bound NGF or BDNF electrostatically immobilised onto an amine functionalized surface to encourage neurite outgrowth and Schwann cell migration. The bioactive surface was characterised by XPS analysis and ELISA. To assess the effect of the bioactive surface on electrospun fibres, primary chick embryo dorsal root ganglia were used, and neurite outgrowth and Schwann cell migration were measured. Our results showed a significant improvement regarding nerve regeneration, with the growth of neurites of up to 3 mm in 7 days, accompanied by Schwann cells. We hypothesize that the physical guidance provided by the fibres along the sustained delivery of NGF or BDNF created a stimulatory environment for nerve regeneration. Our results were achieved by immobilising relatively low concentrations of neurotrophins (1 ng/ml), which provides a promising, low-cost, and scalable method to improve current nerve guide conduits.

Home nasogastric feeding: integration of services to optimise transition from hospital to home

Introduction: Patients requiring enteral feeding are often discharged to home/care facilities, with feeding usually delivered via Percutaneous-Endoscopic-Gastrostomy (PEG) tube. A cohort of patients may be unsuitable for PEG feeding for clinical reasons. The need for home nasogastric feeding (HNGF) in a home/care facility was identified, necessitating discharge of patients from Naas General Hospital (NGH) on HNGF. Practice change implemented: A discharge process is in place at NGH for patients discharged on home PEG feeding; however no such process existed for HNGF. Additional complications may arise with HNGF due to the risk of tube dislodgement. Due to this risk, an outpatient fast track pathway was developed for reinsertion and x-ray confirmation of tube position. Aim and theory of change: The aim was to provide safe delivery of NGF in a home/care facility, to educate the patient/carer, and to ensure smooth transition from hospital to home by optimising the integration of services in the hospital and community. Targeted population and stakeholders: A small cohort of patients may be suitable for HNGF; this group must be carefully selected by agreement between medical, nursing and dietetic staff in consultation with the patient/carers. Liaison with colleagues in the community –community intervention team, public health nurse and GP is an integral part of the process. Timeline: The target timeline for discharge and continuation of HNGF will be patient specific. Highlights: Hospital guidelines on enteral feeding were updated to include procedures for patients discharged on HNGF. An education resource pack was developed for the patient/carer and patient/carer education was carried out by nursing/dietetic staff. Finally, a link between the hospital and the community intervention team was established. Comments on sustainability: A care pathway is now in place for the successful discharge of patients on HNGF. This process is now available for any patient identified as needing enteral feeding after discharge who are not suitable for PEG feeding. To make this process sustainable, close liaison between all relevant stakeholders is needed to continue to ensure the smooth transition from hospital to home and beyond for these patients, with safe and appropriate monitoring. Comments on transferability: This process may be successfully transferred to other sites/organisations provided support and buy-in from key stakeholders is ensured. Conclusions: Through multidisciplinary teamwork and collaboration between hospital and community teams, discharge on HNGF was successful. The success of this process continues to be evaluated as the pilot patients continues on HNGF. Discussions: Patients were previously not discharged on HNGF at NGH. While little published data exists on outcomes for patients on HNGF, it has been demonstrated that for those unsuitable for PEG placement, HNGF represents a safe long-term alternative, provided a specialist enteral feeding support service is in place1. Lessons learned: A patient related outcome measure will be completed once HNGF is discontinued – in order to evaluate and improve the process from the patient’s perspective.

Over-expression of hNGF in adult human olfactory bulb neural stem cells promotes cell growth and oligodendrocytic differentiation.

The adult human olfactory bulb neural stem/progenitor cells (OBNC/PC) are promising candidate for cell-based therapy for traumatic and neurodegenerative insults. Exogenous application of NGF was suggested as a promising therapeutic strategy for traumatic and neurodegenerative diseases, however effective delivery of NGF into the CNS parenchyma is still challenging due mainly to its limited ability to cross the blood–brain barrier, and intolerable side effects if administered into the brain ventricular system. An effective method to ensure delivery of NGF into the parenchyma of CNS is the genetic modification of NSC to overexpress NGF gene. Overexpression of NGF in adult human OBNSC is expected to alter their proliferation and differentiation nature, and thus might enhance their therapeutic potential. In this study, we genetically modified adult human OBNS/PC to overexpress human NGF (hNGF) and green fluorescent protein (GFP) genes to provide insight about the effects of hNGF and GFP genes overexpression in adult human OBNS/PC on their in vitro multipotentiality using DNA microarray, immunophenotyping, and Western blot (WB) protocols. Our analysis revealed that OBNS/PC-GFP and OBNS/PC-GFP-hNGF differentiation is a multifaceted process involving changes in major biological processes as reflected in alteration of the gene expression levels of crucial markers such as cell cycle and survival markers, stemness markers, and differentiation markers. The differentiation of both cell classes was also associated with modulations of key signaling pathways such MAPK signaling pathway, ErbB signaling pathway, and neuroactive ligand-receptor interaction pathway for OBNS/PC-GFP, and axon guidance, calcium channel, voltage-dependent, gamma subunit 7 for OBNS/PC-GFP-hNGF as revealed by GO and KEGG. Differentiated OBNS/PC-GFP-hNGF displayed extensively branched cytoplasmic processes, a significant faster growth rate and up modulated the expression of oligodendroglia precursor cells markers (PDGFRα, NG2 and CNPase) respect to OBNS/PC-GFP counterparts. These findings suggest an enhanced proliferation and oligodendrocytic differentiation potential for OBNS/PC-GFP-hNGF as compared to OBNS/PC-GFP.

P2‐390: Emerging relationship between development and degeneration: TrkA‐APP interaction as a therapeutic target in Alzheimer's disease

It has been proposed that disrupted retrograde transport of NGF-TrkA complexes underlies basal forebrain cholinergic neuron (BFCN) degeneration in Alzheimer's disease (AD). Indeed, targeted BFCN delivery of NGF has been found promising in AD treatment and is currently in a phase II clinical trial. The prevailing view of Alzheimer's disease (AD) is that amyloid-beta (Abeta) causes toxicity through chemical and physical mechanisms. Our data suggest that Abeta functions physiologically as an anti-trophin, and Abeta binding to APP induces APP processing to multiple peptides that mediate physiological neurite retraction and synaptic reorganization (Nat Med 6:397; PNAS 103:7130). An unbiased screen for compounds that block APP caspase cleavage identified ADDN1351, which reduced APP-C31 by 90%. Surprisingly, ADDN1351 proved to be a TrkA inhibitor. We then evaluated the effect of TrkA over-expression on APP-C31 production and cell death induction through transfection, Western blots and MTT assays. We also studied the interaction between APP and TrkA through co-immunoprecipitation and APP-Gal4 transactivation. Furthermore, we treated PDAPP transgenic mice with TrkA inhibitor GW441756 (10mg/kg, 5 days) and assayed the levels of Abeta and sAPPalpha through ELISA and AlphaLISA. TrkA over-expression increased APP-C31 and cell death. APP-C31 cleavage did not occur with the kinase-dead TrkA mutant or in the presence of TrkA inhibitor GW441756, whereas induction was enhanced by NGF. TrkA was shown to interact with APP in co-immunoprecipitation. In APP-Gal4 transactivation assays, TrkA inhibited the transactivation directed by Fe65 or Mint3/YAP by over 90%. Moreover, treatment of PDAPP transgenic mice with GW441756 not only decreased Abeta, but also increased sAPPalpha. These results suggest TrkA inhibition-rather than NGF activation-as a novel therapeutic approach, and raise the possibility that such an approach may counteract the hyperactive signaling resulting from the accumulation of active NGF-TrkA complexes due to reduced retrograde transport. The results also suggest that the optimal therapy for AD may involve both the delivery of NGF or NGF mimetics to basal forebrain cholinergic neuron somata and a TrkA inhibitor that is active more distally.

Development of affinity-based delivery of NGF from a chondroitin sulfate biomaterial

Chondroitin sulfate is a major component of the extracellular matrix in both the central and peripheral nervous systems. Chondroitin sulfate is upregulated at injury, thus methods to promote neurite extension through chondroitin sulfate-rich matrices and synthetic scaffolds are needed. We describe the use of both chondroitin sulfate and a novel chondroitin sulfate-binding peptide to control the release of nerve growth factor. Interestingly, the novel chondroitin sulfate-binding peptide enhances the controlled release properties of the chondroitin sulfate gels. While introduction of chondroitin sulfate into a scaffold inhibits primary cortical outgrowth, the combination of chondroitin sulfate, chondroitin sulfate-binding peptide and nerve growth factor promotes primary cortical neurite outgrowth in chondroitin sulfate gels.

Local delivery of NGF to basal forebrain in AD patients

Local delivery of NGF to basal forebrain in AD patients

P2-424: Delivery of NGF to the brain: Intranasal versus ocular administration in transgenic mice

P2-424: Delivery of NGF to the brain: Intranasal versus ocular administration in transgenic mice

Experimental study on directional control-released delivery of NGF through sclera

目的 探讨巩膜外植入神经生长因子(NGF)药膜后其眼内的药代动力学改变,研究该药膜是否有缓释效果,改善NGF给药途径.方法 筛选与NGF有亲和力的胶原组织,制成具有单向缓释功能的药膜,将其植入健康白兔巩膜表面,用ELISA法测定并观察对照组和实验组各时间点玻璃体内NGF质量浓度的变化,用3P97药代动力学程序计算主要药代动力学参数.结果 实验组在药膜植入后2～15 d内NGF质量浓度明显高于对照组,第18 d降至正常.第3 d达到峰质量浓度20.91 ng/ml,半衰期约7.41 d.药-时曲线下面积AUC0-18为232.788 01 ng·d/ml.结论 自制NGF药膜可缓释进入玻璃体,其峰浓度较高,消除半衰期较长,质量浓度波动较小。

GDNF and NGF released by synthetic guidance channels support sciatic nerve regeneration across a long gap.

The present work was performed to determine the ability of neurotrophic factors to allow axonal regeneration across a 15-mm-long gap in the rat sciatic nerve. Synthetic nerve guidance channels slowly releasing NGF and GDNF were fabricated and sutured to the cut ends of the nerve to bridge the gap. After 7 weeks, nerve cables had formed in nine out of ten channels in both the NGF and GDNF groups, while no neuronal cables were present in the control group. The average number of myelinated axons at the midpoint of the regenerated nerves was significantly greater in the presence of GDNF than NGF (4942 +/-1627 vs. 1199 +/-431, P < or = 0.04). A significantly greater number of neuronal cells in the GDNF group, when compared to the NGF group, retrogradely transported FluoroGold injected distal to the injury site before explantation. The total number of labelled motoneurons observed in the ventral horn of the spinal cord was 98.1 +/-23.4 vs. 20.0 +/-8.5 (P < or = 0.001) in the presence of GDNF and NGF, respectively. In the dorsal root ganglia, 22.7% +/- 4.9% vs. 3.2% +/-1.9% (P +/-0.005) of sensory neurons were labelled retrogradely in the GDNF and NGF treatment groups, respectively. The present study demonstrates that, sustained delivery of GDNF and NGF to the injury site, by synthetic nerve guidance channels, allows regeneration of both sensory and motor axons over long gaps; GDNF leads to better overall regeneration in the sciatic nerve.

Why does PEG 400 co-encapsulation improve NGF stability and release from PLGA biodegradable microspheres?

The aim of this work was to understand the mechanism by which co-encapsulated PEG 400 improved the stability of NGF and allowed a continuous release from PLGA 37.5/25 microspheres. Microparticles were prepared according to the double emulsion method. PEG 400 was added with NGF in the internal aqueous phase (PEG/PLGA ratio 1/1 and 1.8/1). Its effect was investigated through interfacial tension studies. Protein stability was assessed by ELISA. A novel application of PEG in protein stabilization during encapsulation was evidenced by adsorption kinetics studies. PEG 400 limited the penetration of NGF in the interfacial film of the primary emulsion. Consequently, it stabilized the NGF by reducing the contact with the organic phase. In addition, it avoided the NGF release profile to level off by limiting the irreversible NGF anchorage in the polymer layers. On the other hand, the amount of active NGF released in the early stages was increased. During microparticle preparation, NaCl could be added in the external aqueous phase to modify the structure of microparticles. This allowed to reduce the initial release rate without affecting the protein stability always encountered in the absence of PEG. PEG 400 appeared of major interest to achieve a continuous delivery of NGF over seven weeks from biodegradable microparticles prepared by the double emulsion technique.

Targeted intraparenchymal delivery of human NGF by gene transfer to the primate basal forebrain for 3 months does not accelerate beta-amyloid plaque deposition.

Nerve growth factor therapy has been proposed as a potential means of preventing degeneration of basal forebrain cholinergic neurons in Alzheimer's disease and thereby improving cognition. However, NGF has been reported to upregulate expression of the beta-amyloid precursor protein, which in turn could accelerate deposition of "mature" beta-amyloid in the brain. To address this possibility, the brains of 16 adult and aged rhesus monkeys were examined for beta-amyloid plaque deposition in the presence or absence of NGF treatment. Six aged monkeys received intraparenchymal grafts into the cholinergic basal forebrain of autologous cells genetically modified to secrete NGF, six aged monkeys received intraparenchymal grafts of autologous control cells expressing the reporter gene beta-galactosidase, and four adult nonoperated monkeys served as additional controls. All brains were examined for expression of mature beta-amyloid using an antibody recognizing amino acids 1-40 of the beta-amyloid peptide. Amyloid plaques were systematically quantified in representative sections of the temporal, frontal, cingulate, insular, and parietal cortices and in the amygdala and hippocampus. Results disclosed that aging resulted in an increase in amyloid plaque formation: no plaques at all were detected in nonaged monkeys, whereas a mean of 20 +/- 13 plaques per section were present in control-aged monkeys. Aged subjects with intraparenchymal NGF-secreting grafts for 3 months contained a mean of 29 +/- 14 plaques per section, an amount that did not differ significantly from control-aged monkeys (P = 0.66). Thus, 3 months of intraparenchymal NGF delivery did not significantly increase beta-amyloid deposition.

Carrier mediated delivery of NGF: Alterations in basal forebrain neurons in aged rats revealed using antibodies against low and high affinity NGF receptors

Carrier mediated delivery of NGF: Alterations in basal forebrain neurons in aged rats revealed using antibodies against low and high affinity NGF receptors

Delivery of 125I-NGF to the Brain via the Olfactory Route

The blood-brain barrier presents a major problem in the administration and testing of neurotropins as it prevents a sufficient concentration of these potential therapeutic agents from reaching the target areas of the human brain. The olfactory neuroepithelium is the only area of the body in which an extension of the central nervous system comes into direct contact with the environment. Following intranasal administration of 125I-labeled nerve growth factor (125I-NGF), radiolabel appeared rapidly in the olfactory bulb and other brain regions. Radiolabel accumulation in the olfactory bulb of the brain was a linear function of the intranasal dose and of the radiolabel concentration in the olfactory epithelium. Concentration of radiolabel in the olfactory bulb and brain with intranasal administration, but not with intravenous administration, suggests direct transport of label into the brain along the olfactory route following intranasal administration. The rapid appearance of label in the olfactory bulbs, cerebrum, and brain stem is more consistent with entry of label through intercellular clefts in the olfactory epithelium and extracellular transport along the olfactory neural pathway to reach the cerebrospinal fluid and brain than with uptake by olfactory neurons and subsequent intracellular axonal transport. At least 80% of the radiolabel found in the brain following intranasal delivery of 125I-NGF precipitates in cold 5% trichloroacetic acid, suggesting that a significant amount of intact NGF reaches the brain. Preliminary studies using a sandwich enzyme-linked immunosorbent assay have confirmed the uptake of NGF into the brain following intranasal but not intravenous administration to rats. This is the first evidence for noninvasive delivery of unconjugated NGF to the brain.