Indirect Low-Intensity Ultrasonic Stimulation for tissue engineering
Increasing evidence indicates that low-intensity ultrasound (LIUS) can be used to help certain body tissues to heal and regenerate. In particular, it has been used to help regenerate cartilage and bone, and in tissue engineering to stimulate cells.
Surgeons use a patient’s own fatty tissue in procedures including facial plastic surgery, treating burn victims, breast reconstruction and surgery on the vocal cords. But how well these tissue grafts survive can vary, and the time period after the surgery before a blood supply is re-established is particularly critical. If the graft doesn’t get sufficient oxygen and glucose, and clear away waste, the grafted tissue will wither and die.
The researchers in this study tested cells cultured from tissue left over from tummy-tuck operations as well as mouse muscle cells for their experiments. Over a six-day period, the test cells were treated with LIUS for short bursts. The results revealed greater cell numbers and better viability for the mouse muscle and the tummy tissue showed significantly increased metabolic activity, and had fewer markers for tissue damage than tissue not treated.
When considering the potential of this treatment the lead author confirms “It may eventually be possible to manipulate cellular responses by fine-tuning this technique.” Preliminary results suggest important avenues to pursue in efforts to improve graft survival.
Low-intensity ultrasound (LIUS) treatment has been shown to increase mass transport, which could benefit tissue grafts during the immediate postimplant period, when blood supply to the implanted tissue is suboptimal. In this in vitro study, we investigated effects of LIUS stimulation on dye diffusion, proliferation, metabolism, and tropomyosin expression of muscle cells (C2C12) and on tissue viability and gene expression of human adipose tissue organoids. We found that LIUS increased dye diffusion within adjacent tissue culture wells and caused anisotropic diffusion patterns. This effect was confirmed by a hydrophone measurement resulting in acoustic pressure 150–341 Pain wells. Cellular studies showed that LIUS significantly increased proliferation, metabolic activity, and expression of tropomyosin. Adipose tissue treated with LIUS showed significantly increased metabolic activity and the cells had similar morphology to normal unilocular adipocytes. Gene analysis showed that tumor necrosis factor-alpha expression (a marker for tissue damage) was significantly lower for stimulated organoids than for control groups. Our data suggests that LIUS could be a useful modality for improving graft survival in vivo.
Park, H., Yip, M., Chertok, B., Kost, J., Kobler, J., Langer, R., & Zeitels, S. (2010). Indirect Low-Intensity Ultrasonic Stimulation for Tissue Engineering Journal of Tissue Engineering, 2010, 1-10 DOI: 10.4061/2010/973530