Effect of oxidized cellulose on human respiratory mucosa and submucosa and its implications for endoscopic skull-base approaches.

BACKGROUND: Regenerated oxidized cellulose (ROC) sheets have gained popularity as an adjunct to a vascularized nasoseptal flap for closure of dural defects after endoscopic endonasal skull-base approaches (EESBS). However, evidence supporting its impact on the healing process is uncertain. This study was performed to evaluate the impact of ROC on the nasal mucosa and assess its effects on tissue pH, structure, and cell viability. METHODS: In 5 patients, a 1-cm2 piece of ROC gauze was placed on the surface of the middle turbinate before it was resected as part of a standard EESBS. Mucosa treated with ROC was separated from untreated mucosa and a histologic examination of structural changes in the respiratory epithelium was performed. To assess the effect of ROC on pH, increasing amounts of ROC were added to culture medium. Nasal fibroblasts viability was assessed in the presence of ROC before and after the pH was neutralized. RESULTS: Compared with unexposed controls, treated mucosa exhibited a higher incidence of cell necrosis and epithelial cell detachment. When added to Dulbecco's modified Eagle medium, ROC caused a dose-dependent decrease in pH of the medium. Only 1 ± 0.8% of cultured fibroblasts exposed to the ROC-induced acidic medium were alive, whereas 98.25 ± 0.5% of the cells were viable when the pH was neutralized (p < 0.001). CONCLUSION: ROC applied in vivo to nasal mucosa induced epithelial necrosis likely by diminishing the medium pH, because pH neutralization prevents its effect. The ultimate effect of this material on the healing process is yet to be determined.

A new model for dura mater healing: human dural fibroblast culture.

OBJECTIVE: Dura mater healing is crucial to prevent cerebrospinal fluid (CSF) leaks after neurosurgical procedures. Biological mechanisms leading to dural closure are only partially understood and have been studied in animals exclusively. We studied an in vitro model of dural closure which uses human cells. MATERIALS AND METHODS: We used human dura intended for disposal after surgery. Explant primary cultures were performed. Cells were characterized through common staining and immunohistochemistry. A cell growth curve was elaborated and the effect of dexamethasone on cell count was assessed. Spongostan®, oxidized regenerated cellulose and autologous plastic materials were also evaluated for their effect on cellular growth. RESULTS: All specimens showed growth in fusiform cells, which project pseudopods and fuse into spindles. Cells showed desmin and vimentin positivity, and were negative for all the other stains, behaving phenotypically like fibroblasts. No collagen base was necessary for cell growth. Dexamethasone decreased cell count in the primary culture as well as in the explant, and reduced the cell proliferation marker Ki-67. Spongostan® was successfully used as a graft, and fibroblast cultures were additionally developed with muscle, pericranium, galea, and fascia. Oxidized cellulose induced cell death by lowering the pH of the solution. DISCUSSION: According to the findings, unlike mini-pigs and rabbits, in humans, dural fibroblast sensitivity to collagen seems to be lower. Dexamethasone inhibits fibroblast invasion, which is the biological base of wound dehiscence in cranial surgery. Although Spongostan is useful, Surgicel® can lower the media pH, thereby inhibiting cellular growth.

Topical hemostatic agents in gynecologic surgery.

Biosurgical compounds and pharmacologic agents can serve as surgical adjuncts to prevent or curtail intraoperative bleeding. Medline, PubMed, and Cochrane electronic data bases were used to search the English literature from 1966 to March 2007 using the terms topical, hemostatic agents, and gynecologic surgery. Several effective topical hemostatic agents are available to reduce intraoperative blood loss. Data on their application in gynecologic surgery are limited, and guidelines for selecting one over another for specific indications are lacking.