Relations between individual cellular motions and proliferative potentials in successive cultures of human keratinocytes.

In the successive cultures of human keratinocyte cells, cellular motions of extension and rotation were analyzed based on observation of the individual cells, to evaluate the proliferative potential in a whole cell population. In lag phases of the serial cultures, an extension index of individual cells, R(E), was defined as an average spreading rate divided by initial cell area for each cell. The mean value of R(E) was found to relate to prolongation of lag time; namely it decreased with increasing passage number in the successive cultures approaching cellular senescence. During the courses of the cultures, the rotation rate of paired cells was also measured through time-lapse observation. The mean value of rotation rate, [Formula: see text], decreased with an increase in doubling time caused by the progress of cellular age, reaching an almost constant value of [Formula: see text] h(-1) in the cultures with prolonged doubling time of over 59 h. It was concluded that the indices determined from the motions of individual cells, R(E) and [Formula: see text], were correlated with the lag time and doubling time, respectively, which are growth parameters varied with the vitality of the cells approaching cellular senescence.