The Highs and Lows of Regenerative Medicine

Nanoscale manipulation on the surface of materials could stimulate cells to differentiate into specific tissues - eliminating the use of growth or transcription factors.

Regenerative Medicine
Cellular characteristics and activities that may be influenced by the interaction between cells and nanoscale topographies.

Researchers are trying to find ways to control cellular response in vitro using engineered materials in a continuous pursuit to regenerate injured or diseased tissues. Recent studies have found that nanoscale structure of the materials, on which such cells are cultured, affect how well they proliferate and develop into the tissues they are meant to become.

Scientists from the University of Malaya in Malaysia, Dr. Belinda Pingguan-Murphy et al., together with Prof. Sheikh Ali Akbar of Ohio State University, reviewed the most recent research on how the nanoscale topographies affect cellular regenerative responses.

For example, human fetal osteoblast cells that are involved in bone formation were found to grow better on materials that had tiny protrusions on their surfaces (11 nanometers in height) compared to surfaces that were either flat or had higher protrusions. They also attached better to surfaces with nanosized pits that were 14 nm or 29 nm deep compared to flat surfaces and surfaces with pits that were 45 nm deep.

Research has also found that the distance between pits or protrusions and whether they are random or highly ordered also affect how osteoblasts and stem cells respond. Additionally, nanoscale grooved surfaces trigger these cells to grow in the direction of the grooves.

Generally, when a material is exposed to a biological fluid, water molecules bind rapidly to the surface followed by the incorporation of chloride and sodium ions. Proteins then adsorb to this surface. The resulting mixture of proteins, as well as their three-dimensional shape and orientation with respect to the surface topography, sends signals to the cells influencing their attachment and spreading.

Further research in this area may lead to the development of clinical prostheses with topographies that can directly modulate stem cell fate, enabling cell growth and development to be tailored to a specific application without using potentially harmful chemicals, write the researchers in their review published in the journal of Science and Technology of Advanced Materials. However, developing low-cost, high-output fabrication techniques that allow for the development of specific nano-topographies is still a limiting factor.