Long term regeneration of cis-platinum and X ray treated human tumor nodules maintained in continuous organotypic culture.

A simple method for maintaining tumor cells in continuous three-dimensional culture, derived from Wolff's organotypic technique, has been used to study the effects of cis-platinum and X rays on growth inhibition, regrowth and long term regeneration of cultures maintained in low traumatizing conditions (absence of enzymatic dissociation of the cells and the possibility of avoiding subculturing, if necessary). The tumor nodules were derived from cells of the A 549 lung carcinoma cell line. The nodules developed an alveolar structure. After 1 h treatment with 15 micrograms/ml cis-platinum the growth of the nodules was slightly inhibited during the first 10 days, and then resumed normal growth. After treatment with 100 micrograms/ml cis-platinum, growth inhibition lasted longer and regrowth was observed after about 30 days. Treatment with 300 micrograms/ml of cis-platinum induced cell necrosis and loss of alveolar structures. Forty days later, regeneration occurred; two months after the drug treatment, the reconstituted nodules could be routinely subcultured. A single 15 Gy X ray dose (inducing a 0.005% survival in A 549 monolayer cells, n = 8; D0 = 1.4 Gy; Dq = 1.48) caused an early growth inhibition of about 25%. The alveolar structures disappeared. Alveolar structures reappeared in 17% of the nodules 50 days after irradiation. A slight regrowth was observed 90 days after the irradiation. A 549 nodules supported an about 20-fold higher cis-platinum concentration than monolayer cells. An almost lethal X ray dose (15 Gy, inducing a survival of 0.005%) for monolayer cells induced a prolonged lag phase in nodules followed by a slight but regular regrowth. These results support the idea that cells maintained in three dimensional culture are more resistant to radiation and drug-induced injury than monolayer cells. The organotypic culture method may be a useful tool for determining the activity of antitumoral agents.