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We devised a simple method to isolate mitotically active human Schwann cells from sural nerve biopsy specimens and expand the population in culture. Nerve fascicles were treated with cholera toxin for 7 days in culture before dissociation, which increased the cell yield at least twenty-five-fold over immediated tissue dissociation. Digesting the tissue completely with enzymes in serum-containing medium resulted in the highest cell viability, and released 2 to 6 x 10(4) cells/mg of tissue. Seeding the cells on a poly-L-lysine substrate in a small volume of serum-free medium optimized the plating efficiency. Although Schwann cells comprised 90% of the initial culture population, their numbers declined over time due to a faster mitotic rate of the fibroblasts in the presence of cholera toxin alone. However, treating the cultures with a combination of cholera toxin and forskolin, which act synergistically to elevate cyclic AMP levels, inhibited fibroblast growth without causing Schwann cell toxicity. Adding glial growth factor to the adenyl cyclase activators maximized Schwann cell proliferation, and the population rapidly and selectively expanded. Therefore, it should be possible to generate large numbers of Schwann cells from diseased nerves to study defects in cell function or from normal nerves to study the effects of Schwann cell grafts on neuronal regeneration.

Leukotrienes are pharmacologically active compounds that promote vascular permeability. In this study we sought to determine whether tissue leukotriene-like immunoreactivity was increased in intracranial tumors associated with peritumoral edema. In 20 patients undergoing craniotomy tissue specimens were immediately frozen after removal and tissue leukotriene C4 levels were determined by radioimmunoassay. An index of peritumoral edema was estimated from preoperative contrast-enhanced computed tomographic scans. There was a significant correlation between brain edema and tissue leukotriene levels (p less than 0.003). Metastatic tumors (n = 8) had the highest leukotriene C4 level at 13.8 +/- 8.5 pg/mg tissue (mean +/- SE) and the highest index of edema 5.7 +/- 1.8. The mean leukotriene C4 level in the gliomas (n = 5) was 6.2 +/- 2.3 pg/mg tissue and the edema index was 2.1 +/- 0.6. There was no edema and no neoplasm in the temporal lobes removed for seizure (n = 2), and their level of leukotriene C4 was 0.4 +/- 0.1 pg/mg tissue. The formation of leukotriene C4 is stimulated by intracranial tumors. Leukotrienes increase blood-brain barrier permeability and may be important in the formation of vasogenic edema surrounding tumors.