Effect of hyaluronan on calcification-nodule formation from human periodontal ligament cell culture

The periodontal ligament (PDL) has been found to house progenitor elements which may give rise to a new periodontium when properly triggered. Complex molecular mechanisms are involved in guiding such cells towards their final regenerative task. Hyaluronan (HA), an extracellular matrix molecule abundantly present during early tissue development, is usually found at high concentrations in all adult mammalian PDL tissue. In this study, PDL cells were cultured on HA coated experimental plastic Petri's dishes (E.D.) and mineralized-nodules formation, at the microscopical level, was evaluated in comparison to HA-free control dishes (C.D.) after 21 days. Little colony formation occurred in presence of HA, whereas CD showed normal cell confluence with mineralization of nodules even at 10 days. However, when harvesting was performed from both dishes after only 12 hours, before cell aggregation occurred, cell confluence and nodule formation could be seen with no apparent difference between test and control. This study shows that, with respect to PDL cells, hyaluronan seems to inhibit cell adhesion, although with no interference with cell aggregates calcifying potentials. This latter finding may: a) provide further insight in analyzing the properties of extracellular matrix substrates in the PDL environment, b)guide research to possible explanations on how the PDL maintains its characteristics of uncalcified tissue and c) lead to theorize regarding utilization in tissue regeneration. (Journal of Applied Biomaterial & Biomechanics 2003; 1: 84-90).