Repair of peripheral nerve with vein wrapping.

OBJECTIVE: The post-traumatic neuro-anastomosis must be protected from the surrounding environment. This barrier must be biologically inert, biodegradable, not compressing but protecting the nerve. Formation of painful neuroma is one of the major issues with neuroanastomosis; currently there is no consensus on post-repair neuroma prevention. Aim of this study is to evaluate the efficacy of neuroanastomosis performed with venous sheath to reduce painful neuromas formation, improve the electrical conductivity of the repaired nerve, and reduce the discrepancies of the sectioned nerve stumps. PATIENTS AND METHODS: From a trauma population of 320 patients treated in a single centre between January 2008 and December 2011, twenty-six patients were identified as having an injury to at least one of the peripheral nerves of the arm and enrolled in the study. Patients were divided into two groups. In the group A (16 patients) the end-to-end nerve suture was wrapped in a vein sheath and compared with the group B (10 patients) in which a simple end-to-end neurorrhaphy was performed. The venous segment used to cover the nerve micro-suture was harvested from the superficial veins of the forearm. The parameters analyzed were: functional recovery of motor nerves, sensitivity and pain. RESULTS. Average follow-up was 14 months (range: 12-24 months). The group A showed a more rapid motor and sensory recovery and a reduction of the painful symptoms compared to the control group (B). CONCLUSIONS: The Authors demonstrated that, in their experience, the venous sheath provides a valid solution to avoid the dispersion of the nerve fibres, to prevent adherent scars and painful neuromas formation. Moreover it can compensate the different size of two nerve stumps, allowing, thereby, a more rapid functional and sensitive recovery without expensive devices.

Co-targeting the MAPK and PI3K/AKT/mTOR pathways in two genetically engineered mouse models of schwann cell tumors reduces tumor grade and multiplicity.

Malignant peripheral nerve sheath tumors (MPNSTs) are soft tissue sarcomas that occur spontaneously, or from benign plexiform neurofibromas, in the context of the genetic disorder Neurofibromatosis Type 1 (NF1). The current standard treatment includes surgical resection, high-dose chemotherapy, and/or radiation. To date, most targeted therapies have failed to demonstrate effectiveness against plexiform neurofibromas and MPNSTs. Recently, several studies suggested that the mTOR and MAPK pathways are involved in the formation and progression of MPNSTs. Everolimus (RAD001) inhibits the mTOR and is currently FDA approved for several types of solid tumors. PD-0325901 (PD-901) inhibits MEK, a component of the MAPK pathway, and is currently in clinical trials. Here, we show in vitro than MPNST cell lines are more sensitive to inhibition of cellular growth by Everolimus and PD-901 than immortalized human Schwann cells. In combination, these drugs synergistically inhibit cell growth and induce apoptosis. In two genetically engineered mouse models of MPNST formation, modeling both sporadic and NF1-associated MPNSTs, Everolimus, or PD-901 treatment alone each transiently reduced tumor burden and size, and extended lifespan. However, prolonged treatment of each single agent resulted in the development of resistance and reactivation of target pathways. Combination therapy using Everolimus and PD-901 had synergistic effects on reducing tumor burden and size, and increased lifespan. Combination therapy allowed persistent and prolonged reduction in signaling through both pathways. These data suggest that co-targeting mTOR and MEK may be effective in patients with sporadic or NF1-associated MPNSTs.

mTORC1 inhibition delays growth of neurofibromatosis type 2 schwannoma.

BACKGROUND: Neurofibromatosis type 2 (NF2) is a rare autosomal dominant genetic disorder, resulting in a variety of neural tumors, with bilateral vestibular schwannomas as the most frequent manifestation. Recently, merlin, the NF2 tumor suppressor, has been identified as a novel negative regulator of mammalian target of rapamycin complex 1 (mTORC1); functional loss of merlin was shown to result in elevated mTORC1 signaling in NF2-related tumors. Thus, mTORC1 pathway inhibition may be a useful targeted therapeutic approach. METHODS: We studied in vitro cell models, cohorts of mice allografted with Nf2(-/-) Schwann cells, and a genetically modified mouse model of NF2 schwannoma in order to evaluate the efficacy of the proposed targeted therapy for NF2. RESULTS: We found that treatment with the mTORC1 inhibitor rapamycin reduced the severity of NF2-related Schwann cell tumorigenesis without significant toxicity. Consistent with these results, in an NF2 patient with growing vestibular schwannomas, the rapalog sirolimus induced tumor growth arrest. CONCLUSIONS: Taken together, these results constitute definitive evidence that justifies proceeding with clinical trials using mTORC1-targeted agents in selected patients with NF2 and in patients with NF2-related sporadic tumors.

Regression of schwannomas induced by adeno-associated virus-mediated delivery of caspase-1.

Schwannomas are tumors formed by proliferation of dedifferentiated Schwann cells. Patients with neurofibromatosis 2 (NF2) and schwannomatosis develop multiple schwannomas in peripheral and cranial nerves. Although benign, these tumors can cause extreme pain and compromise sensory/motor functions, including hearing and vision. At present, surgical resection is the main treatment modality, but it can be problematic because of tumor inaccessibility and risk of nerve damage. We have explored gene therapy for schwannomas, using a model in which immortalized human NF2 schwannoma cells expressing a fluorescent protein and luciferase are implanted in the sciatic nerve of nude mice. Direct injection of an adeno-associated virus (AAV) serotype 1 vector encoding caspase-1 (ICE) under the Schwann-cell specific promoter, P0, leads to regression of these tumors with essentially no vector-mediated neuropathology, and no changes in sensory or motor function. In a related NF2 xenograft model designed to cause measurable pain behavior, the same gene therapy leads to tumor regression and concordant resolution of tumor-associated pain. This AAV1-P0-ICE vector holds promise for clinical treatment of schwannomas by direct intratumoral injection to achieve reduction in tumor size and normalization of neuronal function.

Spinal and cutaneous schwannomatosis is a variant form of type 2 neurofibromatosis: a clinical and molecular study.

OBJECTIVE: To delineate the clinical phenotype, molecular basis, and implications for screening in patients and families with multiple schwannomas not generally involving the cranium. METHODS: As part of a United Kingdom clinical and genetic study of type 2 neurofibromatosis (NF2) patients and families with multiple schwannomas who do not fulfil diagnostic criteria for NF2 have been identified. The clinical phenotype was studied in the extended families and molecular analysis was carried out at the NF2 gene locus on chromosome 22. RESULTS: Patterns of inheritance in five families with schwannomatosis are consistent with inheritance of an autosomal dominant gene. The consistency of phenotype, with relative sparing of the cranium, is constant in these families. However, families which initially seem to be indicative of schwannomatosis may develop into classic NF2 as shown by a sixth family. Many of the tumours found in these families were referred to as "neurofibroma" when they were clearly schwannomas. This difference in classification has major implications for the relative risk of each particular type of neurofibromatosis and neuropathological review may be important in some cases. Genetic linkage analysis in the two largest families is entirely consistent with primary involvement of the NF2 gene. CONCLUSIONS: Variant forms of neurofibromatosis have presented a dilemma in classification and determination of recurrence risks in families. Previous reports have suggested that schwannomatosis is a sporadic non-hereditary condition. Patients with multiple schwannomas are likely to have a variant form of NF2 and up to a 50% risk of passing on a gene predisposing to multiple schwannoma.

Influence of the postnatal administration of tumor necrosis factor plus interferon-alpha 2b on the development of ethyl-nitrosourea-induced brain tumors in rats.

Using the experimental model of brain tumors induced by ethyl-nitrosourea (ENU), interferon-alpha 2b and human recombinant tumor necrosis factor-alpha (TNF) have been administered to Wistar rats between 100 and 130 days of life (one injection each week, by intraperitoneal route, of 100 micrograms of TNF and 10(4) IU of interferon-alpha 2b, in a total volume of 1 ml per injection). The results obtained suggest, that at this time, this association achieves a reduction in the number of so-called 'malignant schwannomas', but it does not influence the time of appearance nor the number of so-called 'malignant schwannomas', but it does not influence the time of appearance nor the number of so-called 'oligodendroglioma-like tumors'. On the basis of previous observations about cytokine modulation of these ENU-induced neoplasms, a different course of time for obtaining a postnatal biomodulation of both type of tumors is suggested.

Influence of recombinant interleukin-2 and tumor necrosis factor-alpha on the development of ethyl nitrosourea-induced brain tumors.

Using the experimental model of brain tumors induced by ethyl-nitrosourea (ENU), human recombinant interleukin-2 (rIL-2) and tumor necrosis factor-alpha (TNF-alpha) were administered to Wistar rats in early stages of carcinogenesis. The results obtained suggest that IL-2 does not influence the development of nervous system tumors. In contrast, TNF-alpha was capable of modulating the development of ENU-induced tumors, producing a reduction in the number of schwannomas and a delay in the appearance of intraparenchymatous brain tumors.

Effect of long-term administration of retinoids on rats exposed transplacentally to ethylnitrosourea.

A neurogenic cancer model, involving transplacental administration of ethylnitrosourea (ENU) to Sprague-Dawley rats, was employed to evaluate the efficacy of retinyl acetate, 13-cis-retinoic acid, and all-trans-retinoic acid in prevention of nervous system tumors in the offspring. Supplementation of the diet with either of these retinoids did not alter the incidence, number, or latency period of the induced neurogenic tumors. Long-term administration of high doses of 13-cis-retinoic acid (240 mg/kg of diet) or all-trans-retinoic acid (65 mg/kg of diet) produced lethal toxicity in this strain of rats, possibly due to interference with vitamin K absorption and the resulting internal hemorrhages associated with hypoprothrombinemia. Prolonged feeding of retinyl acetate increased the retinyl palmitate level in the liver. The concentration reached was not dose-dependent; a maximum level (approximately 10-fold that of controls) was observed after six months of feeding. An unexpected observation was the decrease in liver retinyl palmitate concentration in the livers of rats fed 13-cis-or all-transretinoic acid.

Reduction of N-nitroso-N-ethylurea-induced neurogenic tumors by X-radiation: a life-span study in rats.

Whole-body X-irradiation after neonatal injection with N-nitroso-N-ethylurea (ENU) significantly reduced the incidence of induced neurogenic tumors in inbred HMT rats kept for their complete life-span. After administration of 10 mg ENU/kg and 1.25 Gy X-radiation, the incidence of schwannomas but not of gliomas was reduced as compared to the incidence in rats given 10 mg ENU/kg only. In contrast, after administration of 4 mg ENU/kg, 1.25 Gy reduced the incidence of gliomas but not of schwannomas. Administration of 1.25 Gy alone induced a remarkably high incidence of rats with neurogenic tumors (20%). Latency of tumor detection was not significantly affected by radiation. Among the most frequently occurring nonneurogenic tumors, squamous cell carcinomas were reduced in incidence by treatment with ENU, 1.25 Gy X-radiation, or both combined. No treatment affected the incidence of pituitary or mammary tumors. There was a preponderance of ovarian tumors in rats given 4 mg ENU/kg + 1.25 Gy. An incidental finding was the occurrence of granular cell tumors in 7 rats from different treatment groups.

Immunity to transplantable nitrosourea-induced neurogenic tumors. II. Immunoprophylaxis of tumors of the brain.

An effective method was sought to immunize rats against the growth of intracerebrally (IC) injected T9 tumor, a gliosarcoma cell line. Rats which were immunized with either 10(6) T9 cells mixed with 0.14 mg C. parvum, or 10(7) irradiated T9 cells showed tumor immunity to intradermal (ID) transplantation. However, to obtain tumor immunity to an IC challenge of T9 cells, rats initially had to reject an ID challenge of T9 cells. After sequential rejections of ID challenges of as many as 10(7) cells, a high degree of immunity was obtained, allowing rejection of up to 5 X 10(6) T9 cells injected IC. Spleen cells from highly immunized rats mixed with T9 cells at a ratio of 1:25 (tumor:spleen) destroyed T9 tumor cells in a Winn test. Normal spleen cells had no effect on tumor growth. We conclude that: 1) T9 cells are moderately immunogenic, 2) an effective method of immunization of CDF rats against ID transplanted T9 cells is 10(6) T9 cells with 0.14 mg C. parvum or 10(7) irradiated T9 cells, 3) a higher degree of tumor immunity is necessary to reach the brain than is needed to reach the periphery, and 4) spleen cells of highly immunized rats are cytotoxic to T9 tumor cells.

Effect of levamisole on malignant experimental neurinoma grown subcutaneously in a young rat: brief communication.

Levamisole, a drug that stimulates the immunologic defenses of the host, was tested on the experimental malignant neurinoma grown subcutaneously in young female inbred CDF rats in 3-month trial. The drug resulted in prevention of tumor growth in 80% of the treated animals, whereas tumors grew in 100% of the controls. After discontinuation of the drug, none of the animals in the treated group showed evidence of tumor growth upon clinical and pathologic examination 1 month after drug treatment was terminated. Treated animals failed to show any side effects related to levamisole upon clinical and pathologic examination.

Chemotherapeutic effects of some alkylating derivatives of nitrosourea on the development of tumors transplacentally induced in rats by ENU.

The application of BCNU, CCNU and MeCCNU has been shown to greatly reduce the number of tumors induced in rats by transplacentally administered ENU and to inhibit the full development of tumor proliferation. Moreover, no neurinomas appeared after treatment with CCNU. The application of GCNU proved to be much less effective. Our statistics in the form of tables showing these findings are included and discussed.