Nanotubes Expedite the Healing Power of Stem Cells

Proceedings of the National Academy of Sciences, February 1, 2009

Scientists at the University of California at San Diego have discovered how to combine nanotubes with adult stem cells to accelerate bone growth.

In what represents yet another novel convergence of previously disparate fields, namely, medicine and the strictly inorganic field of materials science, bioengineers have taken mesenchymal stem cells that were derived from bone marrow and grown them on the tops of very thin titanium oxide nanotubes. Such a procedure, the scientists discovered, allows for greater control over the differentiation of the stem cells. More specifically, it is by varying the dimensions of the nanotubes that selective differentiation of the stem cells can be induced, such as, for example, into osteoblasts for the repair of injured bone. Simply stated, the larger the diameter of the nanotube, the larger the resulting elongation of the surface of the stem cells when compared to those stem cells that are grown on narrower nanotubes.

According to Dr. Sungho Jin, a coauthor of the paper, "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. 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 crutches for 3 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."

Dr. Seunghan Oh, another author of the article, adds, "What we have accomplished here is a way to introduce desirable guided differentiation using only nanostructures instead of resorting to chemicals."

As Dr. Jin further explains, "The use of nano-topography to induce preferred differentiation was reported in recent years by other groups, but such studies were done mostly on polymer surfaces, which are not desirable orthopedic implant materials." According to Dr. Shu Chien, director of the new Institute of Engineering in Medicine at UC San Diego, "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."

Indeed, the field of regenerative medicine is becoming increasingly interdisciplinary, as the mere name of the newly established Institute of Engineering in Medicine suggests. The previous, erroneous paradigm in which distinct and separate scientific and medical fields are somehow expected to evolve independently of each other is demonstrably false, today more than ever before. Increasingly so, it is the cross-pollenation of ideas between disciplines which is driving the advancement of science and technology, and which is an especially vital and essential ingredient in the development of successful stem cell therapies.