Articulating the "stem cell niche" paradigm through the lens of non-model aquatic invertebrates.

Stem cells (SCs) in vertebrates typically reside in "stem cell niches" (SCNs), morphologically restricted tissue microenvironments that are important for SC survival and proliferation. SCNs are broadly defined by properties including physical location, but in contrast to vertebrates and other "model" organisms, aquatic invertebrate SCs do not have clearly documented niche outlines or properties. Life strategies such as regeneration or asexual reproduction may have conditioned the niche architectural variability in aquatic or marine animal groups. By both establishing the invertebrates SCNs as independent types, yet allowing inclusiveness among them, the comparative analysis will allow the future functional characterization of SCNs.

Muscarinic receptors modulate Nerve Growth Factor production in rat Schwann-like adipose-derived stem cells and in Schwann cells.

Regenerative capability of the peripheral nervous system after injury is enhanced by Schwann cells (SCs) producing several growth factors. The clinical use of SCs in nerve regeneration strategies is hindered by the necessity of removing a healthy nerve to obtain the therapeutic cells. Adipose-derived stem cells (ASCs) can be chemically differentiated towards a SC-like phenotype (dASCs), and represent a promising alternative to SCs. Their physiology can be further modulated pharmacologically by targeting receptors for neurotransmitters such as acetylcholine (ACh). In this study, we compare the ability of rat dASCs and native SCs to produce NGF in vitro. We also evaluate the ability of muscarinic receptors, in particular the M2 subtype, to modulate NGF production and maturation from the precursor (proNGF) to the mature (mNGF) form. For the first time, we demonstrate that dASCs produce higher basal levels of proNGF and mature NGF compared to SCs. Moreover, muscarinic receptor activation, and in particular M2 subtype stimulation, modulates NGF production and maturation in both SCs and dASCs. Indeed, both cell types express both proNGF A and B isoforms, as well as mNGF. After M2 receptor stimulation, proNGF-B (25 kDa), which is involved in apoptotic processes, is strongly reduced at transcript and protein level. Thus, we demonstrate that dASCs possess a stronger neurotrophic potential compared to SCs. ACh, via M2 muscarinic receptors, contributes to the modulation and maturation of NGF, improving the regenerative properties of dASCs.

Changes in HbA1c and circulating and adipose tissue androgen levels in overweight-obese women with polycystic ovary syndrome in response to electroacupuncture.

AIM: Insulin sensitivity is ~40% lower in women with polycystic ovary syndrome (PCOS) than in controls. We tested the hypothesis that 5 weeks of electroacupuncture treatment improves glucose regulation and androgen levels in overweight/obese women with PCOS. MATERIAL AND METHODS: Seventeen women with PCOS, aged 18 to 38 years, with a body mass index (BMI) ≥25 kg/m2 and diagnosed with PCOS were included in this experimental and feasibility study and subjected to five weeks of electroacupuncture treatments three times/week. The primary outcome was changes in whole-body glucose homeostasis measured by euglycemic hyperinsulinemic clamp before and after the intervention. Secondary outcome were changes in HbA1c, circulating catecholamines, adipocyte size and adipose tissue expression of sex steroids and nerve growth factor (NGF). RESULTS: No significant change in glucose homeostasis was observed, but HbA1c decreased by 9.5% (p = 0.004), circulating testosterone decreased by 22% (p = 0.0007) and dihydrotestosterone decreased by 12% (p = 0.007). The two vagal activity markers of plasma serotonin levels and the dopamine metabolite homovanillic acid decreased by 21% (p = 0.027) and 20% (p = 0.011), respectively. Adipose tissue concentrations of testosterone decreased by 18% (p = 0.049), and androstenedione decreased by 13% (p = 0.035), and mature NGF/proNGF ratio, a marker of sympathetic activity, increased (p = 0.04). These changes occurred without changes in anthropometrics. CONCLUSION: Five weeks of electroacupuncture treatment improves HbA1c and circulating and adipose tissue androgens in women with PCOS. This effect is mediated, at least in part, via modulation of vagal activity and adipose tissue sympathetic activity. Based on these findings, we have recently initiated a randomized controlled study (NTC02647827).

Nerve Growth Factor (NGF) up-regulation in the cerebrospinal fluid of newborns with myelomeningocele.

BACKGROUND: Neurotrophic factors, such as Nerve Growth Factor (NGF), play a key role in the stimulation of sprouting, synaptic plasticity, and reorganization after spinal cord damage. AIM: The aim of this study was to investigate the expression of nerve growth factor (NGF) in the cerebrospinal fluid (CSF) of newborns with myelomeningocele (MMC) and to determine its correlation with this spinal malformation. PATIENTS AND METHODS: To measure the expression of NGF, we collected CSF samples of 14 newborns with MMC taken immediately before the neurosurgical correction of the spinal malformation and of 14 matched controls. Endogenous NGF levels were quantified using a two-site immuno-enzymatic assay. The statistical analysis was performed using the Mann-Whitney two-tailed two-sample test. RESULTS: In the CSF of patients with MMC, NGF levels showed a significant increase compared to the mean levels of the control group (63.05 ± 7.3 vs 18.32 ± 4.5 pg/mL; (p < 0.001). No correlation was found between NGF expression and different types of MMC malformation, such as the level of spinal lesion and the association with Chiari II syndrome. CONCLUSIONS: Our study shows an over-expression of NGF in the CSF of newborns with MMC. The observed pattern of NGF up-regulation in this subset of patients may stimulate axonal sprouting and synaptic reorganization of the damaged neural cells at the site of spinal cord injury, thereby representing an important biochemical marker of spinal cord damage in MMC patients.

Electroacupuncture counteracts the development of thermal hyperalgesia and the alteration of nerve growth factor and sensory neuromodulators induced by streptozotocin in adult rats.

AIMS/HYPOTHESIS: Diabetes is considered the leading cause of neuropathies in developed countries. Dysfunction of nerve growth factor (NGF) production and/or utilisation may lead to the establishment of diabetic neuropathies. Electroacupuncture has been proved effective in the treatment of human neuropathic pain as well as in modulating NGF production/activity. We aimed at using electroacupuncture to correct the development of thermal hyperalgesia and the tissue alteration of NGF and sensory neuromodulators in a rat model of type 1 diabetes. METHODS: Adult rats were injected with streptozotocin to induce diabetes and subsequently treated with low-frequency electroacupuncture for 3 weeks. Variation in thermal sensitivity was studied during the experimental course. Hindpaw skin and spinal cord protein content of NGF, NGF receptor tyrosine kinase A (TrkA), substance P (SP), transient receptor potential vanilloid 1 (TRPV1) receptor and glutamic acid decarboxylase-67 (GAD-67) were measured after electroacupuncture treatments. The skin and spinal cord cellular distribution of TrkA was analysed to explore NGF signalling. RESULTS: Early after streptozotocin treatment, thermal hyperalgesia developed that was corrected by electroacupuncture. The parallel increases in NGF and TrkA in the spinal cord were counteracted by electroacupuncture. Streptozotocin also induced variation in skin/spinal TrkA phosphorylation, increases in skin SP and spinal TRPV1 and a decrease in spinal GAD-67. These changes were counteracted by electroacupuncture. CONCLUSIONS/INTERPRETATION: Our results point to the potential of electroacupuncture as a supportive therapy for the treatment of diabetic neuropathies. The efficacy of electroacupuncture might depend on its actions on spinal/peripheral NGF synthesis/utilisation and normalisation of the levels of several sensory neuromodulators.

Acupuncture in clinical and experimental reproductive medicine: a review.

BACKGROUND: Acupuncture has been used as treatment for infertility for hundreds of years, and recently it has been studied in male and female infertility and in assisted reproductive technologies, although its role in reproductive medicine is still debated. AIM: To review studies on acupuncture in reproductive medicine, in experimental and clinical settings. METHODS: Papers were retrieved on PubMed and Google Scholar and were included in the review if at least the abstract was in English. RESULTS: There is evidence of benefit mainly when acupuncture is performed on the day of embryo transfer (ET) in the live birth rate. Benefit is also evident when acupuncture is performed for female infertility due to polycystic ovary syndrome (PCOS). There is some evidence of sperm quality improvement when acupuncture is performed on males affected by idiopathic infertility. Experimental studies suggest that acupuncture effects are mediated by changes in activity of the autonomic nervous system and stimulation of neuropeptides/neurotransmitters which may be involved in the pathogenesis of infertility. CONCLUSIONS: Acupuncture seems to have beneficial effects on live birth rate when performed on the day of ET, and to be useful also in PCOS as well as in male idiopathic infertility, with very low incidence of side effects. However, further studies are necessary to confirm the clinical results and to expand our knowledge of the mechanisms involved.

Hair cells in non-vertebrate models: lower chordates and molluscs.

The study of hair cells in invertebrates is important, because it can shed light on the debated question about the evolutionary origin of vertebrate hair cells. Here, we review the morphology and significance of hair cells in two groups of invertebrates, the lower chordates (tunicates and cephalochordates) and the molluscs. These taxa possess complex mechanoreceptor organs based on both primary (sensory neurons) and/or secondary, axonless, sensory cells, bearing various apical specializations. Compared with vertebrates, these taxa show interesting examples of convergent evolution and possible homologies of sensory systems. For example, the "lateral line organ" of Octopoda and Decapoda, composed of primary sensory cells aligned on the arms and the head, is considered a classic example of convergent evolution to mechanoreception. Similarly, in ascidians, the cupular organ, formed of primary sensory cells embedded in a gelatinous cupula, is seen as an analog of neuromasts in vertebrates. However, the coronal organ of the oral siphon of ascidians, represented by a line of secondary sensory cells with a hair bundle also comprising graded stereovilli, is currently the best candidate for tracing the evolutionary origin of the vertebrate octavo-lateralis system. Several features, such as embryological origin, position, gene expression and morphology, support this hypothesis.

Streptozotocin-induced diabetes is associated with changes in NGF levels in pancreas and brain.

Type 1 diabetes mellitus (DM), a "classical" result of a pancreatic-beta cell damage, is associated with various metabolic, neuronal, endocrine and immune alterations at cellular, tissue and organ levels. Nerve growth factor (NGF) is one of the most extensively studied neurotrophic factors, which is produced and released by numerous cells including the pancreatic beta cells. NGF plays an important role during brain development and may be able to delay or even reverse damaged forebrain cholinergic neurons that undergo degeneration in aged animals and in Alzheimer's disease (AD). Recent reports indicate that experimentally induced DM in rodents can cause brain biochemical and molecular alterations similar to those observed in sporadic AD. Given the importance of NGF in the pathophysiology of brain cholinergic neurons, we looked for NGF changes in the pancreas and brain of diabetic rats. The aim of this study was, therefore, to investigate the effect of streptozotocin-induced DM on NGF and NGF receptor expression in pancreas and brain. The results showed that DM is associated with altered NGF, NGF-receptor expression in both pancreas and brain.

Hair cells in an ascidian (Tunicata) and their evolution in chordates.

In ascidians, mechanoreceptors of the oral area are involved in monitoring the incoming water flow. Sensory cells are represented by scattered, ciliated primary cells (sending their own axons to the cerebral ganglion) or secondary sensory cells (axonless cells forming afferent and efferent synapses with neurons, whose somata are located in the ganglion) of the coronal organ. Coronal cells have varying morphologies: in species of the Enterogona order, they are multiciliate, whereas those of Pleurogona possess an apical apparatus composed of one or two cilia accompanied by stereovilli, in some cases also graded in length. The coronal organ has been proposed as a homologue to the vertebrate octavo-lateralis system, because coronal cells resemble vertebrate hair cells for morphology, embryonic origin and arrangement. In the ascidian Molgula socialis (Pleurogona), we now describe the morphology of the coronal organ, which contains a few associated rows of sensory cells that run the whole length of the oral velum and the branched tentacles. Three kinds of sensory cells, accompanied by specialised supporting cells, are present. Comparisons between the coronal organ and other chordate mechanosensory structures suggest that hair cells originated in the common ancestor of chordates.

Botryllus schlosseri: a model ascidian for the study of asexual reproduction.

Botryllus schlosseri, a cosmopolitan colonial ascidian reared in the laboratory for more than 50 years, reproduces both sexually and asexually and is used as a model organism for studying a variety of biological problems. Colonies are formed of numerous, genetically identical individuals (zooids) and undergo cyclical generation changes in which the adult zooids die and are replaced by their maturing buds. Because the progression of the colonial life cycle is intimately correlated with blastogenesis, a shared staging method of bud development is required to compare data coming from different laboratories. With the present review, we aim (1) to introduce B. schlosseri as a valuable chordate model to study various biological problems and, especially, sexual and asexual development; (2) to offer a detailed description of bud development up to adulthood and the attainment of sexual maturity; (3) to re-examine Sabbadin's (1955) staging method and re-propose it as a simple tool for in vivo recognition of the main morphogenetic events and recurrent changes in the blastogenetic cycle, as it refers to the developmental stages of buds and adults.

Effect of exercise on ovarian morphology and expression of nerve growth factor and alpha(1)- and beta(2)-adrenergic receptors in rats with steroid-induced polycystic ovaries.

Oestadiol valerate (EV)-induced polycystic ovaries (PCO) in rats cause anovulation and cystic ovarian morphology. Denervation of ovarian sympathetic nerves restores ovulatory disruption. In the present study, we determined whether 5 weeks of voluntary exercise influence ovarian morphology and the expression of sympathetic markers in the EV-induced PCO rat model. The effect of exercise on (i) ovarian morphology; (ii) mRNA and protein expression of nerve growth factor (NGF); and (iii) mRNA and number of ovarian-expressing cells for the NGF receptor (p75 neurotrophin receptor) and the alpha(1a)-, alpha(1b)-, alpha(1d)- and beta(2)-adrenergic receptors (ARs) in rats with EV-induced PCO was evaluated. PCO was induced by a single i.m. injection of EV, and controls were injected with oil alone in adult cycling rats. The rats were divided into four groups: (i) control (oil); (ii) exercise group (oil + exercise); (iii) a PCO group (EV); and (iv) a PCO exercise group (EV + exercise). The exercise and PCO exercise groups ran voluntarily for 5 weeks in computer-monitored wheels placed in the cages where they were housed. The results obtained indicated that ovarian morphology was almost normalised in the PCO exercise group; NGF mRNA and protein concentrations were normalised in the PCO exercise group; high numbers of NGF receptor expressing cells in PCO ovaries were lowered by exercise; and the number of immunopositive cells of the different AR subtypes were all reduced after exercise in the PCO group, except for the alpha(1b)- and beta(2)-AR whereas the mRNA levels were unaffected, indicating transcriptional regulation. In conclusion, our data indicate a beneficial effect of regular exercise, as a modulator of ovarian sympathetic innervation, in the prevention and treatment of human PCOS.

Production and purification of a calcium-dependent protease from Bacillus cereus BG1.

The production and purification of a calcium-dependent protease by Bacillus cereus BG1 were studied. The production of the protease was found to depend specifically on the calcium concentration in the culture medium. This suggests that this metal ion is essential for the induction of protease production and/or stabilisation of the enzyme after synthesis. The calcium requirement is highly specific since other metal ions (such as Mg(2+) and Ba(2+), which both activate the enzyme) are not able to induce protease production. The most appropriate medium for growth and protease production comprises (g L(-1)) starch 5, CaCl(2) 2, yeast extract 2, K(2)HPO(4) 0.2 and KH(2)PO(4) 0.2. The protease of BG1 strain was purified to homogeneity by ultrafiltration, heat treatment, gel filtration on Sephacryl S-200, ion exchange chromatography on DEAE-cellulose and, finally, a second gel filtration on Sephacryl S-200, with a 39-fold increase in specific activity and 23% recovery. The molecular weight was estimated to be 34 kDa on SDS-PAGE. The optimum temperature and pH of the purified enzyme were determined to be 60 degrees C and 8.0, respectively, in 100 mM Tris-HCl buffer + 2 mM CaCl(2).

Topical application of nerve growth factor in human diabetic foot ulcers. A study of three cases.

Three diabetic patients with leg or foot ulcers unresponsive to conventional therapies were treated with topical application of Nerve Growth Factor (NGF). The results showed that NGF promotes healing after 5-14 weeks of treatment. This study suggests that the use of topical application of NGF may represent a new useful tool for the management of difficult diabetic ulcers.

Nerve growth factor promotes reparative angiogenesis and inhibits endothelial apoptosis in cutaneous wounds of Type 1 diabetic mice.

AIMS/HYPOTHESIS: The neurotrophin nerve growth factor (NGF) is pro-angiogenic and facilitates wound repair. The present study was conducted to (i) assess the statement of NGF system components in diabetic wounds and (ii) evaluate whether NGF supplementation could prevent impairment of wound neoangiogenesis by diabetes. METHODS: Skin wounds were produced in the interscapular region of streptozotocin-induced diabetic mice. NGF (1 microg per day in PBS) or vehicle was applied onto the ulcers for 3 days after punching. Non-diabetic mice were used as controls. RESULTS: In wounds of untreated diabetic mice, endogenous levels of immunoreactive NGF were lower than those in wounds of non-diabetic mice ( p<0.01). Immunohistochemical analysis showed down-regulation of tyrosine kinase receptor-A (TrkA) and up-regulation of p75 receptor in granulation tissue microvasculature. Local NFG administration prevented diabetes-induced expressional alterations, enhanced reparative capillarisation ( p<0.01), and accelerated wound closure ( p<0.01). This was associated with a three-fold increase in endothelial cell proliferation ( p<0.01), while apoptosis was reduced by 50% ( p<0.05). Quantitative RT-PCR documented a 5.5-fold increase in the expression of vascular endothelial growth factor-A (VEGF-A) by exogenous NGF in diabetic tissues ( p<0.01). In in vitro preparations of human endothelial cells from derma, NGF increased the release of immunoreactive VEGF-A, and reduced high-glucose-induced apoptosis ( p<0.05), the latter effect being inhibited by a VEGF-A receptor-2 antagonist. CONCLUSIONS/INTERPRETATION: Diabetic ulcers display distinct alterations in reparative angiogenesis and in the expression of NGF and its receptors. NGF supplementation corrects endogenous liabilities, facilitates vascular regeneration, and suppresses endothelial apoptosis seemingly via VEGF-A. Our findings unravel new mechanisms responsible for NGF reparative action.

Nerve growth factor release by human synovial fibroblasts prior to and following exposure to tumor necrosis factor-alpha, interleukin-1 beta and cholecystokinin-8: the possible role of NGF in the inflammatory response.

OBJECTIVE: Aim of this study was to investigate the synthesis, release and effects of nerve growth factor (NGF) in human synovial cells isolated from synovial tissue specimen from healthy and osteoarthritis (OA) patients. METHODS: Human synovial fibroblasts cultures were established starting from healthy and osteoarthritis patients. NGF protein levels in the culture medium, NGFmRNA and high-affinity NGF receptor (Tyrosine kinase A: TrkA) expression in the cells were evaluated in basal conditions and after stimulation with pro-inflammatory cytokines or with the neuropeptide cholecystokinin-8 (CCK-8). The effect of NGF supplement to culture medium on cell proliferation, TrkA expression, and tumour necrosis factor-alpha (TNF-alpha) and inducible-nitric oxide synthase (iNOS) production was investigated. RESULTS: Under basal conditions human synovial cells produce and release NGF. Both interleukin-1-beta (IL-1 beta) and TNF-alpha, but not CCK-8 promote NGF synthesis and release from OA cells. TrkA NGF receptors are also expressed in both normal and OA synovial cells. NGF, but not IL-1 beta, TNF-alpha and CCK-8, enhances the expression of TrkA in isolated synovial cells. NGF down-regulates IL-1 beta-induced TNF-alpha and iNOS production by OA synovial fibroblasts. CONCLUSIONS: NGF is produced and released and TrkA receptors are expressed in synovial inflammation. Overexpression of NGF in inflammed joints might be involved in the modulation rather than in the induction of the joint inflammatory response.

Clinical application of nerve growth factor on human corneal ulcer.

Nerve growth factor (NGF) is a neurotrophic and immunomodulatory factor contributing of the control of cutaneous morphogenesis, wound healing and inflammatory responses. Following the evidence that topical administration of NGF leads to healing of human corneal ulcers, we investigate the therapeutic action of NGF on immune and/or autoimmune cutaneous ulcers. We found that 1-10 micrograms of highly purified murine NGF dissolved in 50 microliters of physiological solution and topically applied to skin ulcer leads, after 4-12 weeks of daily treatment (depending on the size and depth of the lesion) to complete healing of the ulcer. Thus, NGF was able to promote complete repair in human skin and corneal ulcers which were poorly or non-responsive to conventional topical and systemic treatments. No side effects were observed and a follow up after 4 months showed no signs of relapse. These findings indicate that failure of cutaneous tissues to produce sufficient amounts of NGF might represent a prominent mechanism implicated in the clinical manifestation of ocular ulcers.

Role of cholecystokinin-8 in nerve growth factor and nerve growth factor mRNA expression in carrageenan-induced joint inflammation in adult rats.

OBJECTIVES: The aim of our study was to investigate the role of cholecystokinin-8 (CCK-8), which is able to induce the synthesis of nerve growth factor (NGF), in the joint inflammation of carrageenan-injected rats. METHODS: Adult rats were injected in the ankle joint with carrageenan, with or without CCK-8 or a CCK receptor antagonist (proglumide), and tissue swelling, NGF levels and NGF mRNA expression were assessed. RESULTS: Expression of NGF and NGF mRNA increased transiently after carrageenan injection. This effect was not altered by CCK-8 injection but was inhibited by the CCK receptor antagonist. The decrease in NGF level after treatment with the antagonist was concurrent with an increase in paw swelling. CONCLUSIONS: The results demonstrate that, whereas CCK-8 has no anti-inflammatory action in carrageenan-injected animals, proglumide induces a worsening of inflammation and reduces the expression of both NGF and NGF mRNA in inflamed ankle joints. Our data point to a regulatory action of CCK-8 on NGF synthesis during acute synovitis and suggest a role for NGF in the healing phase of inflammation.

Cholecystokinin-8 and nerve growth factor: two endogenous molecules working for the upkeep and repair of the nervous system.

Cholecystokinin-8 (CCK-8), the small peptide initially described as a gastric factor involved in the regulation of feeding behavior, is today recognized as one of the most abundant neurotransmitters/ neuropeptides in brain and is an important signal factor for the peripheral and central nervous systems. In the past twenty years, many studies have focused on possible clinical applications of this peptide and its receptor ligands in psychiatric diseases and gastrointestinal pathologies. Recently it has been suggested that CCK-8 may also have a neuroprotective role, thus opening a new field of interest around the physiology and the pharmacology of this neuropeptide and its receptors. It has been demonstrated that CCK-8 counteracts neuronal deficit following chemical or surgical lesions in both the central and peripheral nervous systems and that Nerve Growth factor (NGF) is involved in the CCK-induced recovery process. By using selective CCK receptor antagonists it has been demonstrated that CCK-8, when injected intraperitoneally, has the ability to stimulate NGF synthesis in brain and peripheral organs by a mechanism that involves the activation of CCK receptors. As has been widely reported, NGF is an essential survival and differentiative factor for selective neuronal populations of the PNS and CNS and plays a role in the events of degeneration and repair of the nervous system in diseases with different etiologies, e.g. neurodegenerative and autoimmune diseases as well as diabetes-associated pathologies. The possibility of using NGF in therapy has been evaluated and systemic and intracerebral NGF treatment have been tested in patients and animal models. Although the results of these studies are encouraging, the difficulty to predict and/or eliminate the side effects of NGF/NGF antibody treatment has made it difficult to fully evaluate the potential of the beneficial effects. In this context recent results obtained in our laboratories may offer a new prospective for the pharmacological approaches to the diseases associated with altered NGF production and functions. The data of our recent observations on NGF and CCK-8 is covered in this review.