Behavior of sea urchin primary mesenchyme cells in artificial extracellular matrices

The primary mesenchyme cells (PMCs) were separated from the mesenchyme blastulae of Pseudocentrotus depressus using differential adhesiveness of these cells to plastic Petri dishes. These cells were incubated in various artificial extracellular matrices (ECMs) including horse serum plasma fibronectin, mouse EHS sarcoma laminin, mouse EHS sarcoma type IV collagen, and porcine skin dermatan sulfate. The cell behavior was monitored by a time-lapse videomicrograph and analysed with a microcomputer. The ultrastructure of the artificial ECM was examined by transmission electron microscopy (TEM), while the ultrastructure of the PMCs was examined by scanning electron microscopy (SEM). The PMCs did not migrate in type IV collagen gel, laminin or dermatan sulfate matrix either with or without collagen gel, whereas PMCs in the matrix which was composed of fibronectin and collagen gel migrated considerably. However, the most active and extensive PMC migration was seen in the matrix which contained dermatan sulfate in addition to fibronectin and collagen gel. This PMC migration involved an increase not only of migration speed but also of proportion of migration-promoted cells. These results support the hypothesis that the mechanism of PMC migration involves fibronectin, collagen and sulfated proteoglycans which contain dermatan sulfate.