The influence of mouse sera, regenerating liver extracts and bacterial products on the abilities of different cells in vitro.

ABSTRACT

In the complexity of host tumor relations, the regeneration of the tissue in which the tumor is growing, or in some other tissue in the organism, could influence the maturation of tumor cells, i.e. tumor reversion. Clinical observations and experiments on plants, lower animals, or animal embryos, performed by several authors, and our results on the influence of regenerating mouse liver on the abilities of tumor transplanted there or elsewhere in the organism led us to study the in vitro growth of different cells or bacteria exposed to the extracts of normal or regenerating liver and/or sera from these animals. Further, sterile used bacterial media were added to bacterial or cell cultures, respectively. Depending on the model, liver extracts-particularly extracts and sera from mice with regenerating liver-were shown to inhibit radioactive thymidine incorporation in the cells. In these experiments, the number of bacteria or cells per culture was lower than in otherwise treated corresponding cultures. Further, used sterile media of bacterial cultures stimulated the growth of bacteria but inhibited thymidine incorporation into fibrosarcoma cells in vitro. Whether this means that one or several common regulators exist in nature appears as an intriguing, but still completely open question. The idea of controlling tumor growth by using such regulatory growth factors seems very provocative.