RESULTS

The PG concentration in the culture medium at baseline conditions, in the presence of IL-1ß at a concentration of 5ng/ml without and with PST stimulation, is shown in Fig.1. The presence of IL-1ß determines a significant decrease (p<0.05) in PG levels, but when the cells are cultured in the presence of IL-1ß and submitted to PST stimulation statistically significant restoration (p<0.05) of PG production is observed.

The results concerning metabolic production are further confirmed by the morphologic findings obtained by TEM and SEM. Fig. 2 shows chondrocytes photographed by TEM. Fig. 2A shows a cultured cell at basal conditions: the nucleus (N) appears euchromatic, the cytoplasm contains a fair amount of rough endoplasmic reticulum (RER) and lipid droplets. Fig. 2B shows a cell cultured in the presence of IL-1ß and its damage is evident: several vacuoles (V) in the cytoplasm are devoid of typical structures.

Fig. 2C shows a cell cultured in basal condition and submitted to PST stimulation:  the cell shows a good state of health.

Figure 2
A,B,C,D

Figure 3 
A,B,C,D

Fig. 2D shows a cell cultured in the presence of IL-1ß and submitted to PST stimulation; a clear restoration of the cell structures can be observed: the cytoplasm contains rough and smooth endoplasmic reticuli, and lipid droplets. 

Fig. 3 shows the SEM image of cells. Fig. 3A shows cells cultured at baseline conditions: it is interesting to observe that it has retained its spherical shape, some secretion granules and the thick network of collagen fibrils. Fig. 3B shows a cell cultured in the presence of IL-1ß: its damage is clearly evident and this is further confirmed by the loss of cytoplasmic processes and by the presence of superficial alterations. Fig. 3C shows a cell cultured at basal conditions and submitted to PST stimulation: its SEM image shows the presence of abundant matrix fibers and secretion granules. Fig. 3D shows a cell cultured in the presence of IL-1ß and submitted to PST stimulation; a clear restoration of the cell structures can be observed as confirmed by the presence of several surface granules. 

DISCUSSION

Chondrocyte cultures represent a valid and simplified biological model in which the effects and influence of various factors on the synthesys and degradation of extracellular components can be tested. They also can be used for morphological and ultrastructural evaluations. 

In this study we have tested the effects of PST stimulation on the morphology and metabolism of in vitro human chondrocytes. These tests confirm the studies already carried out on in vitro experimental models: IL-1ß induces a decrease in the production of PG. When the cells were cultivated in the presence of IL-1ß and submitted to PST stimulation there was a restoration of PG concentration in the culture medium. The results concerning metabolic production are further confirmed by the morphological and ultrastructural evaluations obtained by TEM and SEM.

These data demonstrate the protective role played by PST which counteracts the IL-1ß induced effects on chondrocytes in vitro. These results confirm in vitro the data obtained in clinical studies on patients with osteoarthritis.
Further studies are necessary in order to clarify the importance of this approach in for the treatment of cartilage disorders, such as osteoarthritis