Mitotic autoregulation, growth control and neoplasia.

Abstract A model is proposed for the mitotic autoregulation of the haemopoietic stem cell population. Conditions are derived for the model population to exhibit spontaneous self-limitation; these consist of the satisfaction of algebraic inequality relationships between mathematical parameters referring to the global porperties of the model cell population. Violation of these conditions precludes the possibility of spontaneous self-limitation of the population, which therefore grows indefinitely, but is not synonymous with abolition of all responsiveness to homeostatic regulation. Non-limiting growth modes exist for which “cybernetic” responsiveness to perturbations occur. It is suggested that certain features of the model accord well with some observed characteristics of neoplasia, such as the non-localized “field phenomena” frequently seen in tumour growth and the continued responsiveness of some tumours to hormones and other physiological signals.