Irradiation Effects of hMSC on Titanium Surfaces in vitro

Objectives: Patients treated with dental implants may suffer from maxillo-facial cancer and thus receive irradiation treatment. The response of the hMSC on therapeutic irradiation will be of importance for the regenerative potential of the peri-implant bone as well as bone integration with implants placed into irradiated bone. It was the object of the present study to investigate the growth of hMSc on titanium surfaces following irradiation.
Methods: Bone marrow derived hMSC were seeded on different surfaces consisting of commercially pure grade 2 titanium, cp grade 4 fluoride-modified titanium and plastic. Twenty-four hours later the samples were exposed to radiation with single doses of 0, 2, 6 or 10 Gy. The hMSC growth media was changed regularly and saved for analysis (LDH, Total protein and Luminex) at 5 time-points. At day 21 the coins were split into two groups. In one group the cells were fixed with 4% paraformaldehyde, stained with an immune fluorescence technique and studied in a confocal laser-scanning microscope. The cells on the other group of coins and on plastic was washed and stored dry in -80°C for Real-Time PCR analysis.
Results: The visual results from the confocal laser-scanning microscope at day 21 showed a significant difference between the two titanium surfaces. The smooth surface of the non-modified titanium had no or very few cell nuclei present, but showed clearly traces of collagen. The rougher surface of the fluoride-modified titanium showed all over more vial cells evenly spread, with the presence of collagen and actin in context with the amount of cell nuclei. There were no visible differences corresponding to increased radiation dosage.
Conclusions: The findings in the present study indicate that hMSC are better and more stable attached to the rougher surface of the fluoride-modified titanium compared to the smooth machined surface of the non-modified titanium.