Gene therapy for laryngeal paralysis.

OBJECTIVES: The surgical options for laryngeal paralysis only achieve static changes of vocal fold position. Laryngeal reinnervation procedures have had little impact on the return of dynamic laryngeal function. The development of a new treatment for laryngeal paralysis, aimed at the return of dynamic function and neurologic restoration and regeneration, is necessary. METHODS: To assess the possibility of gene therapy for laryngeal paralysis aiming for the return of dynamic laryngeal function, we investigated the therapeutic effects of gene therapy using rat laryngeal paralysis models. RESULTS: In a rat vagal nerve avulsion model, we transferred glial cell line-derived neurotrophic factor (GDNF) gene into the nucleus ambiguus using an adenovirus vector. Two and 4 weeks after the GDNF gene transfer, a significantly larger number of surviving motoneurons was observed. These neuroprotective effects of GDNF gene transfer were enhanced by simultaneous brain-derived neurotrophic factor gene transfer. In a rat recurrent laryngeal nerve crush model, we transferred GDNF gene into recurrent laryngeal nerve fibers after crush injury. Two and 4 weeks after GDNF gene transfer, we observed significantly faster nerve conduction velocity and better vocal fold motion recovery. CONCLUSIONS: These results indicate that gene therapy could be a future treatment strategy for laryngeal paralysis. Further studies will be necessary to demonstrate the safety of the vector before clinical application.

Adenoviral gene transfer of BDNF and GDNF synergistically prevent motoneuron loss in the nucleus ambiguus.

We have previously shown that neuroprotective effects of an adenoviral glial cell line-derived neurotrophic factor (GDNF) gene transfer on the lesioned adult rat motoneurons in the nucleus ambiguus. In the present study, we examined neuroprotective effects of adenoviral gene transfer of brain-derived neurotrophic factor (BDNF) or/and GDNF to motoneurons in nucleus ambiguus using an adult rat vagal nerve avulsion model. The animals avulsed and inoculated with adenoviral vectors encoding BDNF (AxCAmBDNFME) or/and GDNF (AxCAhGDNF) showed immunolabeling for BDNF or/and GDNF in the nucleus ambiguus on the treated side, respectively, and expression of virus-induced BDNF or/and GDNF mRNA transcripts in the brainstem tissue that contained the nucleus ambiguus of the treated side. The treatment with AxCAhGDNF or AxCAmBDNFME significantly prevented the loss of vagal motoneurons in comparison to the control; the protective effect of AxCAmBDNFME was greater than that of AxCAhGDNF. The combined treatment with AxCAmBDNFME and AxCAhGDNF acted synergistically and significantly larger number of vagal motoneurons was preserved as compared to either AxCAmBDNFME treatment or AxCAhGDNF treatment. The treatment with AxCAmBDNFME or/and AxCAhGDNF after avulsion also suppressed the activity of nitric oxide synthase in lesioned motoneurons in the nucleus ambiguus. These results indicate that adenovirus-mediated BDNF and GDNF gene transfer may prevent the degeneration of motoneurons in humans after either vagal nerve injury or recurrent laryngeal nerve injury.

Basaloid squamous carcinoma of the hypopharynx with an extensive spindle cell component exhibiting a pedunculated polypoid mass.

We report a case of basaloid squamous carcinoma of the hypopharynx with an extensive spindle cell component in an 82-year-old man. The tumor (4.0 x 2.5 x 2.2 cm) was a pedunculated polypoid mass that was attached to the left pyriform sinus. Histologically, most (70%) of the tumor was composed of malignant spindle cell proliferation, and the rest (30%) was basaloid squamous carcinoma. Some of the spindle cells were positive for cytokeratins. The preoperative histologic diagnosis was difficult because the endoscopic biopsy specimens showed only spindle cell proliferation. This is an unusual presentation of basaloid squamous carcinoma of the head and neck.

[CHEP with the total removal of the arytenoid on the tumor-bearing side].

A supracricoid laryngectomy with cricohyoidoepiglottopexy (CHEP) consists of the resection of the whole thyroid cartilage and paraglottic space, while preserving the cricoid cartilage, the hyoid bone, most of the epiglottis and the arytenoids. Laryngeal reconstruction is achieved be suturing the cricoid cartilage and the hyoid bone. This procedure is mainly indicated for large T2 glottic carcinomas and provides a complete resection and laryngeal preservation without requiring a permanent tracheostomy. Although bilateral arytenoids are usually preserved to ensure better laryngeal function after CHEP, we unavoidably had to remove the arytenoid on the tumor-bearing side during a complete resection performed in a 56-year-old male with a rT2 tumor who had undergone radiation and demonstrated impaired vocal fold motion. Despite the resection of one arytenoid, the final laryngeal function proved to be satisfactory. CHEP should be utilized as an alternative surgical modality for conventional vertical partial laryngectomies or total laryngectomies. CHEP with the total removal of the arytenoid on the tumor-bearing side may be a useful laryngeal preservation procedure for the treatment of patients with glottic carcinoma associated with an impaired vocal fold motion or a fixed vocal fold.

Adenoviral GDNF gene transfer prevents motoneuron loss in the nucleus ambiguus.

We examined neuroprotective effects of an adenoviral vector encoding glial cell line-derived neurotrophic factor (AxCAhGDNF) on the lesioned adult rat motoneurons in the nucleus ambiguus. After vagal nerve avulsion, AxCAhGDNF, AxCALacZ (adenovirus encoding beta-galactosidase gene) or PBS was inoculated into the jugular foramen. Four days after the avulsion and treatment with AxCALacZ, the animals expressed beta-galactosidase activity in the lesioned motoneurons in the nucleus ambiguus. The animals avulsed and inoculated with AxCAhGDNF showed immunolabeling for GDNF in the nucleus ambiguus on the treated side and expression of virus-induced human GDNF mRNA transcripts in the brainstem tissue that contained the nucleus ambiguus of the treated side. The treatment with AxCAhGDNF after avulsion prevented the loss of lesioned motoneurons in the nucleus ambiguus, ameliorated the choline acetyltransferase immunoreactivity, and also suppressed the activity of nitric oxide synthase in these neurons. These results indicate that adenovirus-mediated GDNF gene transfer may prevent the degeneration of motoneurons in humans after either vagal nerve injury or recurrent laryngeal nerve injury.