Photodynamic Therapy Effect on Synovial Fibroblast Viability

Aim. To evaluate photodynamic therapy effect on synovial fibroblast (SF) viability of inflammatory rheumatoid arthritis (RA) and degenerative osteoarthritis (OA).

Materials and methods. The sam­ples of synovial tissue were taken from the joints of the patients that underwent surgical treatment. SF were cultivated in vitro. Endogenous porphyrins were used as photosensitizers and were produced in the cells from aminolevulinic acid (ALA) and its methyl ester (m-ALA). Cells were irradiated by the blue light of light-emit­ting diod (5 mJ/cm²) with light doses of 50 and 150 mJ/cm². The effect of photo­sensitization was assessed by determin­ing features characteristic of fibroblasts and in the normal culture medium RA-SF exhib­ited higher viability indicators than OA-SF (p<G.G5). The investigation of the impact of two ALA and m-ALA concentrations (G.5 mM and l.G mM) on SF viability in the dark showed, that the highest impact had 1 mM m-ALA solution, but it affected selec­tively only OA fibroblasts by reducing their viability parameters 5 times (p<G.GGl). The impact of light alone and photosensitiza­tion on synovial fibroblasts were investi­gated using two light doses: 5G mJ/cm² and 15G mJ/cm². RA-SF and OA-SF had similar viability parameters when incubated with 1 mM ALA and m-ALA solutions and irra­diated by 5G mJ/cm² light dose. The viabil­ity indicator values of both groups of fibro­blasts, incubated with 1 mM ALA or m-ALA solutions and irradiated with three times higher light dose (15G mJ/cm²), were close to zero. The most suitable con­ditions for in vitro photosensitzation of aggressive RA-FS were established.

Conclusions. Viability parameters of inflammed RA synovial fibroblasts were significantly higher than these of OA fibroblasts when the cells were incu­bated in normal culture medium or with G.5 mM and l.G mM ALA or m-ALA solu­tions. Irradiation of not sensitized fibroblasts with blue light of 15G mJ/cm² dose, had higher impact on more proliferous RA-SF. The most suitible con­ditions for in vitro photosensitization of aggressive RA-FS are following: incuba­tion with the solution of G.5 mM m-ALA and irradiation with 15G mJ/cm² light dose. In this context, the viability of RA-SF is almost completely inhibited down to G.GG2±G.GG r.u. compared to nonirradiated RA-SF (1.95±G.G6 r.u.) at the same conditions.

Keywords: rheumatoid arthritis, osteoarthritis, synovitis, cell viability, photosensitization, aminolevulinic acid.