Objective: To investigate the effect of 1,25 (OH)2 dihydroxyvitamin D3 on the generation of osteoclasts from mononuclear cells of adult rats.
Methods: With density gradient centrifugation, the mononuclear cells were isolated from rat bone marrow and cultured in the alpha-MEM with 10(-8) mol/L 1,25 (OH)2 dihydroxyvitamin D3. The induced cells were fixed and stained with tartrate-resistant acid phosphatase (TRAP). The bone resorption pits were examined by scanning electron microscope, and the morphology of osteoclasts were examined with inverted phase contrast microscope.
Results: The TRAP+ multinucleated cells could be observed on the seventh culturing day of mononuclear cell group. The number of TRAP+ multinucleated cells went up to a peak on the fourteenth culturing day, and then began to decrease on the twenty-first culturing day. The number of osteoclasts induced from mononuclear cell group was more than that from bone marrow group (P < 0.05) when it was during the fourteenth culturing day to the twenty-third culturing day. The number of bone resorption pits in the mononuclear cell group was much more than that in the bone marrow group (P < 0.05) when it was in period from the tenth culturing day to the twenty-third culturing day. The number of osteoclasts induced from mononuclear cell group could keep the peak value of lasting 7 days, but that induced from bone marrow group could only last its peak value for 3 days.
Conclusion: The method with 1,25(OH)2 dihydroxyvitamin D3 inducing the formation of osteoclasts from the marrow mononuclear cells is better than that from the whole bone marrow.