Using nanotubes and stem cells, engineers at the University of California at San Diego have developed a new method to help accelerate bone growth.
The finding could lead to quicker and better recovery, for example, for patients who undergo orthopedic surgery.
In the study, the group of UC San Diego bioengineers and material science experts used a nano-bio technology method of placing mesenchymal stem cells on top of very thin titanium oxide nanotubes in order to control the conversion paths, called differentiation, into osteoblasts or bone building cells.
Mesenchymal stem cells, which are different from embryonic stem cells, can be extracted and directly supplied from a patient's own bone marrow.
"If you break your knee or leg from skiing, for example, an orthopedic surgeon will implant a titanium rod, and you will be on crutches for about three months," said Sungho Jin, co-author of the PNAS paper and a materials science professor at the Jacobs School of Engineering.
Jin added: "But what we anticipate through our research is that if the surgeon uses titanium oxide nanotubes with stem cells, the bone healing could be accelerated and a patient may be able to walk in one month instead of being on crunches for three months.
"Our in-vitro and in-vivo data indicate that such advantages can occur by using the titanium oxide nanotube treated implants, which can reduce the loosening of bones, one of the major orthopedic problems that necessitate re-surgery operations for hip and other implants for patients.
"Such a major re-surgery, especially for older people, is a health risk and significant inconvenience, and is also undesirable from the cost point of view."
This is the first study of its kind using stem cells attached to titanium oxide nanotube implants.
The researchers said that the precise change in nanotube diameter could be controlled to induce selective differentiation of stem cells into osteoblast (bone-forming) cells.
According to this breakthrough research, nanotubes with a larger diameter cause cells growing on their surface to elongate much more than those with a small diameter. The larger diameter nanotube promotes quicker and stronger bone growth.
Scientists said that introducing chemicals into the human body can sometimes have undesirable side effects.
"What we have accomplished here is a way to introduce desirable guided differentiation using only nanostructures instead of resorting to chemicals," said Seunghan (Brian) Oh, who is the lead author of the study.
"Our research in this area has pointed to a novel way by which we can modulate the stem cell differentiation, which is very important in regenerative medicine. This will lead to a truly interdisciplinary approach between engineering and medicine to getting novel treatments to the clinic to benefit the patients," said one of the authors of the study.
The findings of the study 'Stem Cell Fate Dictated Solely by Altered Nanotube Dimension' were published in the Proceedings of the National Academy of Sciences (PNAS).