S. Burchielli

High production of endothelin after foam sclerotherapy: a new pathogenetic hypothesis for neurological and visual disturbances after sclerotherapy

Background Visual and neurological disturbances have always been reported following liquid sclerotherapy (LS) for venous insufficiency. In 1993 Cabrera introduced foam sclerotherapy (FS) using a detergent sclerosant as Lauromacrogol 400 or sodium tetradecyl sulphate. Several authors have reported with FS an increased incidence of such transient visual disturbances and neurological complications. This has been associated with gas or air used to generate the sclerosing foam. The frequent association of the presence of a patent foramen ovale, a common condition in normal population, and such complications has led several authors to consider neurological and visual disturbances as paradoxical gas embolism. Objective We are introducing a new pathogenetic hypothesis for sclerotherapy complications. Medical literature shows evidence of a clear relationship among cerebral and retinal vasospasm, migraine and intimal irritation. We think that the irritating sclerosant agent may stimulate a significant release of vasoactive substances from the venous wall, specifically endothelin 1 (ET-1), the most powerful vasoconstricting agent. Method We have studied systemic ET-1 levels after LS and FS with Lauromacrogol 400 in a group of 13 rats at one and five minutes after injection. Results While ET-1 levels did not change significantly in control and in the LS group, a significant increase was detected after FS at one and five minutes. Conclusion We conclude that should the same results be found in patients treated using sclerosing foam (SF), ET-1 levels may closely correlate to the onset of visual or cerebral complications. Due to the bronchoconstrictor activity of ET-1, a relationship with post-treatment cough can be also postulated.

Significant endothelin release in patients treated with foam sclerotherapy

Background Foam sclerotherapy has been proven to be a safe and effective treatment for superficial venous insufficiency, but transient visual and neurologic disturbances continue to be reported. These side effects have been theorized to be related to the presence of air or gases in the sclerosing foam that results in “bubble” migration into the cerebral circulation. We present a differing hypothesis that significant amounts of endothelin are released from the treated veins, amounts capable of causing these complications. Material and Methods We tested the release of endothelin 1 (ET‐1) in 12 rats after sclerotherapy with sodium tetradecyl sulfate (STS) in liquid and foam preparations. In 11 human subjects, we measured ET‐1 in systemic circulation and in a draining vein after foam sclerotherapy with polidocanol. Results Rats treated with STS showed a significant increase in ET‐1 levels 1 and 5 minutes after foam sclerotherapy. Patients treated with foam sclerotherapy showed a marked increase in ET‐1 levels that correlated significantly with local ET‐1 levels. Conclusions Evidence of ET‐1 release represents a plausible relationship explaining neurologic and visual disturbances reported after sclerotherapy.

Poly(ester urethane) Guides for Peripheral Nerve Regeneration.

A biocompatible and elastomeric PU was synthesized from low-molecular-weight PCL as macrodiol, CMD as chain extender and HDI as chain linker for applications in the field of peripheral nerve repair. PU cast films supported in vitro attachment and proliferation of NOBEC. The in vitro adhesion and proliferation of S5Y5 neuroblastoma cells on the inner surface of uncoated, gelatin- and PL-coated PU guides were compared. Due to their superior in vitro performance, PL-coated PU guides were tested in vivo for the repair of 1.8 cm-long defects in rat sciatic nerves. The progressive regeneration was confirmed by EMG and histological analysis showing the presence of regenerating fibers in the distal stumps.

An autologously generated platelet-rich plasma suturable membrane may enhance peripheral nerve regeneration after neurorraphy in an acute injury model of sciatic nerve neurotmesis.

BACKGROUND The aim of this study was to investigate the ability of suturable platelet-rich plasma (PRP) membrane to promote peripheral nerve regeneration after neurotmesis and neurorraphy. METHODS A total of 36 rats were used: 32 animals underwent surgery and were split in two groups. An interim sacrifice was performed at 6 weeks postsurgery and final sacrifice at 12 weeks; four animals did not sustain nerve injury and served as control. Clinical, electromyographic (EMG), gross, and histological changes were assessed. The EMG signal was evaluated for its amplitude and frequency spectrum. Number of regenerating fibers, their diameter, and myelin thickness were histologically analyzed. RESULTS Both EMG parameters showed a significant (p < 0.05) effect of treatment at 6 and 12 weeks postsurgery. At 6 weeks, the fiber density was statistically different between treated and untreated animals with a higher observed density in treated nerves. No difference in fiber density was observed at 12 weeks postsurgery. The distribution of fiber diameters showed an effect at 12 weeks when only the sections of the nerves sutured with PRP showed fibers with diameters greater than 6 µm. DISCUSSION Our data show that the application of a PRP fibrin membrane around the neurorraphy improves the nerve regeneration process in a rat sciatic nerve model. The use of PRP as a suturable membrane could perform an action not only as a source of bioactive proteins but also as a nerve guide to hold the scar reaction and thus improve axonal regeneration.

The influence of mesh topology in the abdominal wall repair process

The tissue integration and the formation of adhesions in the repair of abdominal wall defects are principally led to the topology and the mechanical properties of implanted prosthesis. In this study we analyzed the influence of the topology of the meshes for abdominal wall repair, made of polypropylene (PP), evaluating its ability to prevent and to minimize the formation of adhesions, and to promote tissue ingrowth. Two series of in vivo studies were performed. In the first, two types of PP meshes, a lightweight macroporous mesh (LWM) and a heavyweight microporous mesh (HWM) were compared with determine the optimal porosity for tissue integration. In the second, a composite mesh, Clear Mesh Composite (CMC), made of a LWM sewn on a PP planar smooth film, was compared with a PP planar film, to demonstrate how two different topologies of same material are able to induce different tissue integration with the abdominal wall and different adhesion with internal organs. In both studies, the prostheses were implanted in Wistar rats and histological analysis and mechanical characterization of tissue coupled with the implants were performed. LWM showed better host tissue ingrowth in comparison to HWM. CMC prosthesis showed no adhesions to the viscera and no strong foreign body reaction, moreover its elasticity and anisotropy index were more similar to that of natural tissue. These results demonstrated that the surface morphology of PP surgical meshes allowed to modulate their repair ability.

Endothelial progenitor cell secretome delivered by novel polymeric nanoparticles in ischemic hindlimb

&NA; Endothelial progenitor cells (EPCs) contribute to ischemic tissue repair by paracrine secretion up‐regulated by hypoxia. In this study we use novel nanoparticles (NPs) as carriers for a controlled release of EPC secretome (CM) to improve their angiogenic properties. The in vivo effect in ischemic hindlimb rat model was evaluated, comparing hypoxic EPC‐CM‐NPs with hypoxic EPC‐CM alone. A proteomic characterization of hypoxic CM and the in vitro effect on endothelial cells (HUVECs) were also performed. Up to 647 protein, 17 of which with angiogenic properties, were upregulated by hypoxia. Moreover, hypoxic EPC‐CM significantly promoted capillary‐like structures on Matrigel. A significant increase of blood perfusion in ischemic limbs at 2 weeks with EPC‐CM‐loaded NPs as compared to both EPC‐CM and control and a significant increase of capillary formation were observed. The use of EPC‐CM‐NPs significantly improved neoangiogenesis in vivo, underlining the advantages of controlled release in regenerative medicine.

Lung inflammation after bleomycin treatment in mice: Selection of an accurate normalization strategy for gene expression analysis in an ex-vivo and in-vitro model

Pulmonary fibrosis (PF) is the most common and aggressive interstitial lung disease, characterized by a patchy development of fibrosis leading to progressive destruction of the normal lung architecture which is preceded by an inflammatory process. Gene expression studies are important to understand the development of PF but the accuracy and reproducibility of Real-Time PCR depend on appropriate normalization strategies. This study aimed to analyze the expression variability of eight commonly used reference genes during the initial inflammatory phase of bleomycin-induced PF in a mouse model and to verify whether the selected reference genes could be applied to an in-vitro model of BLM-treated primary murine lung fibroblasts. Wild-type C57BL/6 mice (n=40) were used. Real-Time PCR was carried out on lung tissue of mice either BLM (BLM-tm) or physiological solution-treated (PSS-tm), and in primary lung fibroblasts, isolated from healthy C57BL/6 mice. Histological analysis was performed to confirm the inflammation development. During inflammation, the most stable genes resulted: PPIA, HPRT-1 and SDHA for both models; the normalization strategy was tested analyzing mRNA expression of PTX-3 and TNF-α which resulted up-regulated both in ex-vivo and in-vitro with respect to PSS-tm/fibroblasts. Histological analysis supported the results. This study identified a new set of reference genes expressed both in the in-vitro and ex-vivo models. A higher expression of both markers in BLM-tm with respect to PSS-tm indicated that BLM might lead to increased PTX-3 local production by a co-regulation with TNF-α at lung level.