Creating a surface that attracts cartilage-forming cells with electrical pulses is one way to regenerate cartilage, says Brown University nanotechnology specialist Thomas Webster. Placing carbon nanotubes around worn surfaces makes a naturally rough surface for cells to grab. Electrical pulses then stimulate the cells to multiply. A study of the method shows it improves cartilage regeneration.

Conventional treatments inject a gel into joints to act as a shock absorber. But it's temporary and require follow-up injections. Previous research tested surfaces which are smoother at the nanoscale. Webster says carbon-nanotube surfaces work better because of their roughness and can be shaped to fit contours where needed.

Webster's team, including Brown researcher Dongwoo Khang and Grace Park from Purdue University, found that the tube's surface properties work well stimulating chondrocytes or cartilage-forming cells.

Researchers also learned they could prod cartilage cells to grow more densely by applying electrical pulses. It is not completely understood why electricity seems to trigger cartilage growth, but the theory is it helps calcium ions enter a cell, and calcium is known to play a role in cartilage growth. The team plans to test its cartilage-regeneration method with animals. If that is successful, research on humans would follow.