• Kei Miyamoto, Howard S An, Robert L Sah, Koji Akeda, Masahiko Okuma, Lori Otten, Eugene J M A Thonar, and Koichi Masuda.
• Department of Orthopedic Surgery, Medical College, Rush University Medical Center, Chicago, IL, USA.
• Spine. 2005 Nov 1; 30 (21): 2398-405.

Study DesignIn vitro study on the effects of pulsed low intensity ultrasound on the cellular metabolism of bovine intervertebral disc cells.ObjectiveTo determine whether pulsed low intensity ultrasound has effects on cell proliferation and extracellular matrix metabolism by bovine intervertebral disc cells.Summary Of Background DataThe application of pulsed low intensity ultrasound is known to be effective in stimulating fracture and cartilage repair. However, the effects of pulsed low intensity ultrasound on intervertebral disc cells are not known.MethodsCells of the nucleus pulposus and inner and outer anulus fibrosus were enzymatically isolated from bovine coccygeal tissue and precultured in alginate beads for 14 days. In the ultrasound group, pulsed low intensity ultrasound was administered to the culture for 20 minutes daily for an additional 20 days. The control group was cultured in the same way but without administration of ultrasound. Cell viability, DNA content, proteoglycan and collagen synthesis, and proteoglycan content at days 10 and 20 after the initiation of treatment were evaluated. Characterization of newly synthesized collagen and proteoglycan was performed.ResultsNo significant differences in cell viability and DNA content were observed between the two groups. On day 20, proteoglycan synthesis was increased by the application of pulsed low intensity ultrasound in nucleus pulposus and inner and outer anulus fibrosus cells (24%-26% increase, P < 0.001). The application of pulsed low intensity ultrasound increased proteoglycan content in alginate beads containing inner and outer anulus fibrosus cells (P < 0.05). Collagen synthesis by cells isolated from all three zones of the intervertebral disc was increased by the application of pulsed low intensity ultrasound (16%-19% increase, P < 0.05-0.0001).ConclusionsThe application of pulsed low intensity ultrasound stimulated extracellular matrix metabolism in intervertebral disc cells. Pulsed low intensity ultrasound may prove useful for the physical stimulation of cell metabolism for tissue engineering of intervertebral disc tissue.

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