Extracellular matrix and cell migration: locomotory characteristics of MOS-11 cells within a three-dimensional hydrated collagen lattice.

The locomotory trajectories of MOS-11 cells migrating in a three-dimensional hydrated collagen lattice have been determined using a computer-assisted optical sectioning unit. The trajectories have been quantified using a three-dimensional continuous-time Markov probability theory consisting of eight directional states and one stationary state; in the latter the cells are not locomoting. Markov analysis shows that these cells are locomoting in a random manner with regard to direction and remain stationary for about three times as long as they are locomoting. Analysis of persistence also implies random locomotion. Compilation of the distribution of angles between steps reveals that the cells exhibit a predilection for turns around 30 degrees and 150 degrees on either side of the previous step. Time-lapse video recordings show that the cells are bi-polar with ruffling membranes at opposite poles. Ruffling, and hence locomotion, occurs alternately at one pole and then the other, which would account for the distribution of angles encountered. The mean speed of the cells was of the order of 3 microns min-1 including the time stopped and approximately twice this if the time stopped (state 0) is not included. The results obtained provide base-line data on the locomotory characteristics of MOS-11 cells locomoting in a 1.2 mg ml-1 collagen gel. It is now possible to study the role of various matrix components in cell locomotion. Such studies are of importance to embryology, wound healing, host defence mechanisms and the invasion of cancer cells.