Effect of Low Intensity Pulsed Ultrasound with Adipose-Derived Stem Cells on Bone Healing around a Titanium Implant in Tibia of Osteoporosis-Induced Rats

ABSTRACT

PURPOSE: Osteoporosis, is a major health problem for the elderly and post-menopausal women and shown to alter the properties of bone as well as impair bone healing around titanium implants in both human and animals. The objective of this study was to examine the effect of LIPUS with adipose-derived stem cells on the healing process around a titanium implant in rats with osteoporosis.METHODS: Sixteen osteoporosis-induced rats were divided into two groups an adipose-derived stem cell injected with Low Intensity Pulsed Ultrasound (LIPUS) application group and a control group. Titanium screw implants (diameter, 2.0 mm length, 3.5 mm, Cowell Medi, Korea) were placed into both tibia of 16 rats, on 8 rats as the control group and the other 8 rats as the experimental group. Rats were sacrificed at different intervals from 1, 2, 4 and 8 weeks after implantation for histopathologic and immunohistochemical analyses.RESULTS: Histopathological analysis revealed newly formed bone in experimental group earlier than that in control group. Especially at 1 week after implantation, more amounts of new bone matrix and collagen around the implant in the experimental group were seen compared with the control group. Immunohistochemical analysis showed that the levels of osteoprotegerin (OPG) expression in the experimental group were increased at early stages compared with that of control group until 2 weeks after implantation. But after 2 weeks, the expression level of OPG similar in both groups. The expression levels of receptor activator of nuclear factor kB ligand (RANKL) were stronger in the experimental group than the control group until 2 weeks after implantation. After 4 weeks, expression of RANKL in experimental group was similar to the control group.CONCLUSION: The results of this study suggest that LIPUS with Adipose-Derived Stem Cells in implantation could promote bone healing around titanium implants in rats with osteoporosis.