Stem cell hope for tissue repair
A new kind of stem cell which knows its place could speed up progress towards revolutionary tissue-repairing treatments, scientists believe.
Researchers in the US created the "region-selective pluripotent stem cells" (rsPSCs) using a cocktail of chemical signals. Not only are they capable of developing into almost any kind of tissue, but they also colonise specific parts of a developing embryo.
Possessing both properties could make it easier to develop workable stem cell therapies aimed at replacing lost tissue.
The cells also offer advantages for large-scale stem cell production and gene modification.
Lead scientist Professor Juan Carlos Izpisua Belmonte, from the Salk Institute in La Jolla, California, said: "The region-specific cells we found could provide tremendous advantages in the laboratory to study development, evolution and disease, and may offer avenues for generating novel therapies."
To create the rsPSCs the team developed a combination of chemical signals that directed conventional human stem cells to become spatially oriented.
Human rsPSCs injected into specific regions of partially dissected mouse embryos soon began to mature and develop into early-stage tissues. In contrast, conventional stem cells failed to integrate.
The region-selective cells began the process of differentiating into the three major cell layers in early embryos, known as the ectoderm, mesoderm and endoderm.
They were stopped from differentiating further, but each layer was theoretically capable of giving rise to specific tissues and organs.
A research paper on the discovery of rsPSCs appears in the journal Nature.
The cells display distinct molecular and metabolic characteristics as well as epigenetic signatures - modifications to DNA that govern the switching on and off of genes.
Co-author Dr Jun Wu, also from the Salk Institute, said: "The region selective-state of these stem cells is entirely novel for laboratory-cultured stem cells and offers important insight into how human stem cells might be differentiated into derivatives that give rise to a wide range of tissues and organs.
"Not only do we need to consider the timing, but also the spatial characteristics of the stem cells. Understanding both aspects of a stem cell's identity could be crucial to generate functional and mature cell types for regenerative medicine."