A novel set of custom-designed “molecular beacons” allows scientists to monitor gene expression in living populations of stem cells as they turn into a specific tissue in real-time. The technology provides tissue engineers with a potentially powerful tool to discover what it may take to make stem cells transform into desired tissue cells more often and more quickly.
The researchers designed their beacons to fluoresce when they bind to mRNA from three specific genes in fat-derived stem cells that are expressed only when the stem cells are transforming into bone cells.
Over a three week period the team watched the populations for the fluorescence of the beacons to see how many stem cells within each population were becoming bone and the timing of each gene expression milestone.
The beacons’ fluorescence made it easy to see a distinct pattern in that timing. Expression of the gene ALPL peaked first in more than 90 percent of induced stem cells on day four, followed by about 85 percent expressing the gene COL1A1 on day 14. The last few days of the experiments saw an unmistakably sharp rise in expression of the gene BGLAP in more than 80 percent of the induced stem cells.
Each successive episode of gene expression ramped up from zero to the peak more quickly, the researchers noted, leading to a new hypothesis that the pace of the stem cell transformation, or “differentiation” in stem cell parlance, may become more synchronized in a population over time.
“If you could find a way to get them on this track earlier, you could get the differentiation faster,” said Eric Darling, assistant professor of biology in the Department of Molecular Pharmacology, Physiology, and Biotechnology at Brown University.
Adapted from the Brown University announcement.