Rocío González-Corrochano

Peripheral nerve regeneration by bone marrow stromal cells

Abstract Adult bone marrow contains stem cells that have attracted interest through their possible use for cell therapy in neurological diseases. Bone marrow stromal cells (MSCs) were harvested from donor adult rats, cultured and pre-labeled with bromodeoxyuridine (BrdU) previously to be injected in the distal stump of transected sciatic nerve of the rats. Distal nerve stump of control rats received culture medium solution. MSCs-treated rats exhibit significant improvement on walking track test at days 18 and 33 compared to controls. Dual immunofluorescence labeling shows that BrdU reactive cells survive in the injected area of transected sciatic nerve at least 33 days after implantation, and almost 5% of BrdU cells express Schwann cell-like phenotype (S100 immunoreactivity). Because MSCs injected in a lesioned peripheral nerve can survive, migrate, differentiate in Schwann cells, and promote functional recovery, they may be an important source for cellular therapy in several neurological diseases.

Diabetes Exacerbates the Functional Deficiency of NO/cGMP Pathway Associated with Erectile Dysfunction in Human Corpus Cavernosum and Penile Arteries

INTRODUCTIONnDiabetic men with erectile dysfunction (ED) are less responsive to therapy with type 5 phosphodiesterase (PDE5) inhibitors. Although an impairment of the nitric oxide (NO)/cyclic guanosin-monophosphate (cGMP) pathway has been shown in diabetic ED vs. non-diabetic ED, the functionality of NO/cGMP pathway in non-diabetic and diabetic ED patients with respect to non-ED patients has not been established.nnnAIMnThe aim of this study is to evaluate the function of NO/cGMP signalling in human erectile tissues from ED patients exploring the added impact of diabetes.nnnMETHODSnCorpus cavernosum strips (human corpus cavernosum [HCC]) and penile resistance arteries (HPRA) were collected from penile specimens from organ donors (OD) and from diabetic and non-diabetic men with ED undergoing penile prosthesis implantation.nnnMAIN OUTCOME MEASURESnRelaxations to acetylcholine, electrical field stimulation, sodium nitroprusside, and sildenafil were evaluated in phenylephrine-contracted HCC and norepinephrine-contracted HPRA. cGMP content in HCC was also determined.nnnRESULTSnThe impairment of endothelium-dependent relaxation in HCC and HPRA from ED patients was exacerbated by diabetes (E(max) 76.1, 62.9, and 49.3% in HCC and 73.1, 59.8, and 46.0% in HPRA from OD, non-diabetic and diabetic ED, respectively). Hypertension, hypercholesterolemia, or aging did not exert a further impairment of endothelial relaxation among ED patients. Diabetes also causes a further impairment of neurogenic relaxation in HCC and HPRA. The basal and stimulated content of cGMP in HCC was significantly decreased in patients with ED, but specially reduced in diabetic patients. Diabetes clearly impaired PDE5 inhibitor-induced vasodilation of HPRA from ED patients.nnnCONCLUSIONSnED is related to impaired vasodilation, reduced relaxant capacity, and diminished cGMP content in penile tissue. These alterations are more severe in diabetes and accompany reduced relaxant efficacy of PDE5 inhibition. Thus, an exacerbated reduction of nitric oxide/cGMP signaling could be responsible for ED in diabetic men and would explain their reduced response to treatment.

Gentisic acid, a compound associated with plant defense and a metabolite of aspirin, heads a new class of in vivo fibroblast growth factor inhibitors.

Fibroblast growth factors are key proteins in many intercellular signaling networks. They normally remain attached to the extracellular matrix, which confers on them a considerable stability. The unrestrained accumulation of fibroblast growth factors in the extracellular milieu, either due to uncontrolled synthesis or enzymatic release, contributes to the pathology of many diseases. Consequently, the neutralization of improperly mobilized fibroblast growth factors is of clear therapeutic interest. In pursuing described rules to identify potential inhibitors of these proteins, gentisic acid, a plant pest-controlling compound, an aspirin and vegetarian diet common catabolite, and a component of many traditional liquors and herbal remedies, was singled out as a powerful inhibitor of fibroblast growth factors. Gentisic acid was used as a lead to identify additional compounds with better inhibitory characteristics generating a new chemical class of fibroblast growth factor inhibitors that includes the agent responsible for alkaptonuria. Through low and high resolution approaches, using representative members of the fibroblast growth factor family and their cell receptors, it was shown that this class of inhibitors may employ two different mechanisms to interfere with the assembly of the signaling complexes that trigger fibroblast growth factor-driven mitogenesis. In addition, we obtained evidence from in vivo disease models that this group of inhibitors may be of interest to treat cancer and angiogenesis-dependent diseases.

Inhibition of vascular endothelial growth factor (VEGF)-induced endothelial proliferation, arterial relaxation, vascular permeability and angiogenesis by dobesilate.

Vascular endothelial growth factor (VEGF) is a key factor in angiogenesis and vascular permeability which is associated with many pathological processes. 2,5-hydroxybenzene sulfonate (DHBS; dobesilate) is a small molecule with anti-angiogenic activity that has been described as an inhibitor of fibroblast growth factors (FGF). The aim of the present study was to evaluate the effects of DHBS on VEGF-induced actions. The effects of DHBS were evaluated on VEGF-induced proliferation in human umbilical vein endothelial cells (HUVEC) and rat aorta relaxation, as well as on in vivo VEGF-induced skin vascular permeability and neovascularization in rats. DHBS at 50 and 100 μM concentration significantly inhibited the proliferation of HUVEC induced by VEGF (10 ng/ml), without significantly affecting HUVEC proliferation in the absence of VEGF. Rapid VEGF-induced activation of Akt in HUVEC was also prevented by DHBS (100 μM). Additionally, DHBS (2 μM) specifically inhibited the relaxation of rat aorta induced by VEGF (0.1 to 30 ng/ml), but not endothelium-dependent relaxation to acetylcholine (1 nM to 10 μM). The in vivo enhancement of vascular permeability caused by VEGF injection (50 μl at 10 ng/ml) in rat skin was also inhibited by DHBS co-administration (200 μM) (74.8±3.8% inhibition of dye extravasation). Administration of DHBS (200 mg/kg/day; i.p.) also reduced VEGF-induced angiogenesis in vivo. DHBS inhibits main responses elicited in vitro and in vivo by VEGF. As a dual antagonist of VEGF and FGF activities, DHBS could be of therapeutic interest in the treatment of diseases related to VEGF/FGF overproduction and excessive angiogenesis.

Heparin modulates the mitogenic activity of fibroblast growth factor by inducing dimerization of its receptor. a 3D view by using NMR.

In vitro mitogenesis assays have shown that sulfated glycosaminoglycans (GAGs; heparin and heparan sulfate) cause an enhancement of the mitogenic activity of fibroblast growth factors (FGFs). Herein, we report that the simultaneous presence of FGF and the GAG is not an essential requisite for this event to take place. Indeed, preincubation with heparin (just before FGF addition) of cells lacking heparan sulfate produced an enhancing effect equivalent to that observed when the GAG and the protein are simultaneously added. A first structural characterization of this effect by analytical ultracentrifugation of a soluble preparation of the heparin‐binding domain of fibroblast growth factor receptor 2 (FGFR2) and a low molecular weight (3 kDa) heparin showed that the GAG induces dimerization of FGFR2. To derive a high resolution structural picture of this molecular recognition process, the interactions of a soluble heparin‐binding domain of FGFR2 with two different homogeneous, synthetic, and mitogenically active sulfated GAGs were analyzed by NMR spectroscopy. These studies, assisted by docking protocols and molecular dynamics simulations, have demonstrated that the interactions of these GAGs with the soluble heparin‐binding domain of FGFR induces formation of an FGFR dimer; its architecture is equivalent to that in one of the two distinct crystallographic structures of FGFR in complex with both heparin and FGF1. This preformation of the FGFR dimer (with similar topology to that of the signaling complex) should favor incorporation of the FGF component to form the final assemblage of the signaling complex, without major entropy penalty. This cascade of events is probably at the heart of the observed activating effect of heparin in FGF‐driven mitogenesis.

The Novel Antioxidant, AC3056 (2,6-di-t-butyl-4-((Dimethyl-4-Methoxyphenylsilyl)Methyloxy)Phenol), Reverses Erectile Dysfunction in Diabetic Rats and Improves NO-mediated Responses in Penile Tissue from Diabetic Men

INTRODUCTIONnDiabetes is associated with a high incidence of erectile dysfunction (ED) and poor response to standard treatments. Oxidative stress could be relevant in the pathophysiology of diabetic ED.nnnAIMnTo evaluate the effects of the antioxidant, AC3056 (2,6-di-t-butyl-4-((dimethyl-4-methoxyphenylsilyl)methyloxy)phenol), on diabetic ED.nnnMETHODSnErectile responses to cavernosal nerve electrical stimulation were determined in streptozotocin-induced diabetic rats. Relaxation of human corpus cavernosal (HCC) tissue and penile resistance arteries (HPRA) from human cavernosal specimens was evaluated in organ chambers and myographs, respectively.nnnMAIN OUTCOME MEASURESnThe influence of AC3056 on erectile responses, lipid peroxidation, and nitrite plus nitrate serum content, and nuclear factor-kappaB (NF-kappaB) expression in penile tissue, in diabetic rats, and on endothelium-dependent and neurogenic relaxation of HCC and HPRA from diabetic patients was determined.nnnRESULTSnEight weeks of diabetes caused ED in rats that was prevented by oral AC3056 (0.3% w/w in rat chow) when given from the induction of diabetes. AC3056 also prevented the diabetes-induced elevation of serum thiobarbituric acid-reactive substances (TBARS), the reduction of serum nitric oxide (NO) derivatives, and the increase of NF-kappaB expression. Acute oral administration of AC3056 (450 mg/kg) partially reversed ED in 8-week diabetic rats. Complete reversion of ED was achieved after 3 days of treatment with 0.3% AC3056. This effect remained after 5 weeks of treatment, but it disappeared after withdrawing for 1 week. Erectile function in diabetic rats was inversely related to serum TBARS. AC3056- (30 microM) reversed endothelial dysfunction in diabetic HCC and enhanced endothelium-dependent relaxation in diabetic HPRA and significantly potentiated neurogenic relaxation of both tissues. The reduced cGMP content in HCC from diabetic patients after exposure to acetylcholine (10 microM) was corrected by AC3056 (30 microM).nnnCONCLUSIONSnThese results suggest that oxidative stress has a relevant role in pathophysiology of diabetic ED and provide a rationale for the use of antioxidant therapy in the treatment of ED in diabetes.

Ca2+‐activated K+ channel (KCa) stimulation improves relaxant capacity of PDE5 inhibitors in human penile arteries and recovers the reduced efficacy of PDE5 inhibition in diabetic erectile dysfunction

We have evaluated the influence of calcium‐activated potassium channels (KCa) activation on cGMP‐mediated relaxation in human penile tissues from non‐diabetic and diabetic patients, and on the effects of PDE5 inhibitors on erectile responses in control and diabetic rats.

Nebivolol Dilates Human Penile Arteries and Reverses Erectile Dysfunction in Diabetic Rats through Enhancement of Nitric Oxide Signaling

INTRODUCTIONnTraditional beta-blockers have sometimes been associated with erectile dysfunction (ED). Nebivolol is a cardioselective β(1)-adrenoceptor antagonist that promotes vasodilation through a nitric oxide (NO)-dependent mechanism.nnnAIMnWe evaluated the effects of nebivolol on the NO/cyclic guanosine monophosphate (cGMP) signaling pathway, on erectile function and dysfunction, and in human penile vascular tissues.nnnMETHODSnErectile response to cavernosal nerve electrical stimulation in control and diabetes-induced ED rats were evaluated, along with serum nitrite/nitrate (NOx) concentration and plasma/tissue cGMP levels. Endothelium-dependent and sildenafil-induced relaxation of isolated human corpus cavernosum (HCC) and human penile resistance arteries (HPRA) were also determined.nnnMAIN OUTCOME MEASURESnThe effects of nebivolol on erectile function and dysfunction and on NO/cGMP-mediated responses.nnnRESULTSnTreatment with nebivolol significantly potentiated erectile response in control rats, regardless of its effects on blood pressure. Nebivolol increased NOx and plasma cGMP by 3-fold and 2.75-fold, respectively, and significantly augmented the elevation of plasma cGMP produced by sildenafil. Nebivolol enhanced endothelium-dependent and sildenafil-induced relaxations of HCC tissue, and produced endothelium-dependent vasodilation of HPRA. Nebivolol, but not atenolol, significantly improved erectile response in diabetic rats (51.6%, 53.2%, and 87.1% of response at 3 Hz in nondiabetic rats, for vehicle-treated, atenolol-treated, and nebivolol-treated diabetic rats, respectively); after sildenafil administration, ED was completely reversed in nebivolol-treated diabetic rats (69.6% and 112% for diabetic rats treated with sildenafil and nebivolol plus sildenafil, respectively). Accordingly, nebivolol restored systemic NOx levels and cGMP content in penile tissue from these animals.nnnCONCLUSIONSnNebivolol in vivo activated the NO/cGMP pathway, enhanced erectile response and reversed ED in diabetic rats. Moreover, nebivolol in vitro potentiated NO/cGMP-mediated relaxation of human erectile tissues. These effects may account for the low incidence of ED in nebivolol-treated hypertensive patients. Nebivolol therefore may have utility in the treatment of ED, particularly ED associated with diabetes.

Antiglioma effects of a new, low molecular mass, inhibitor of fibroblast growth factor.

Despite the deployment of multimodal therapies involving neurosurgical resection, radio- and polychemotherapy, the prognosis for glioblastoma patients remains poor. These tumors are pathologically characterized by their associated angiogenesis and diffuse brain invasion, processes that are probably closely linked to the unfavorable prognosis of this disease. Accordingly, pharmacological inhibition of glioblastoma invasion and approaches that impede angiogenesis are considered to be promising therapeutic strategies to combat these tumors. Nevertheless, the anti-angiogenic therapies for glioblastoma currently available are transient and palliative at best. Blocking the effects of fibroblast growth factor (FGF) may represent a novel mean of inhibiting the angiogenesis associated with glioblastoma, as it mediates the angiogenesis induced by other factors and it is an angiogenic factor by itself. In addition, the survival of glioma cells and their resistance to chemotherapeutic agents are highly FGF-dependent. We show here that a recently described inhibitor of FGF, 2,5-dihydroxyphenyl-sulfonate (2,5DHPS, dobesilate), stimulates the apoptosis of tumor cells, inhibits glioblastoma invasion and suppresses its associated angiogenesis. Moreover, this agent augments the efficiency of chemotherapeutic agents in a rat model of orthotopic brain tumor. These results suggest that 2,5DHPS treatment may represent a promising therapy for malignant glioma.

Stimulation of large-conductance calcium-activated potassium channels inhibits neurogenic contraction of human bladder from patients with urinary symptoms and reverses acetic acid-induced bladder hyperactivity in rats.

We have analysed the effects of large-conductance calcium-activated potassium channel (BK) stimulation on neurogenic and myogenic contraction of human bladder from healthy subjects and patients with urinary symptoms and evaluated the efficacy of activating BK to relief bladder hyperactivity in rats. Bladder specimens were obtained from organ donors and from men with benign prostatic hyperplasia (BPH). Contractions elicited by electrical field stimulation (EFS) and carbachol (CCh) were evaluated in isolated bladder strips. in vivo cystometric recordings were obtained in anesthetized rats under control and acetic acid-induced hyperactive conditions. Neurogenic contractions of human bladder were potentiated by blockade of BK and small-conductance calcium-activated potassium channels (SK) but were unaffected by the blockade of intermediate calcium-activated potassium channels (IK). EFS-induced contractions were inhibited by BK stimulation with NS-8 or NS1619 or by SK/IK stimulation with NS309 (3µM). CCh-induced contractions were not modified by blockade or stimulation of BK, IK or SK. The anti-cholinergic agent, oxybutynin (0.3µM) inhibited either neurogenic or CCh-induced contractions. Neurogenic contractions of bladders from BPH patients were less sensitive to BK inhibition and more sensitive to BK activation than healthy bladders. The BK activator, NS-8 (5mg/kg; i.v.), reversed bladder hyperactivity induced by acetic acid in rats, while oxybutynin was ineffective. NS-8 did not significantly impact blood pressure or heart rate. BK stimulation specifically inhibits neurogenic contractions in patients with urinary symptoms and relieves bladder hyperactivity in vivo without compromising bladder contractile capacity or cardiovascular safety, supporting its potential therapeutic use for relieving bladder overactivity.