Stem cells rescue nerve cells by direct contact

Scientists at the Swedish medical university Karolinska Institutet have shown how transplanted stem cells can connect with and rescue threatened neurons and brain tissue. The results point the way to new possible treatments for brain damage and neurodegenerative diseases.

Two murine neural stem cells (yellow-green) filled with the gap junction permeable dye Calcein (green), rapidly integrate and establish intercellular bridges to surrounding neural cells. This allows direct communication with recipient cells. Here visualised by transfer of calcein into surrounding neural cells-turning them green. Note the presence of green flourophore in several cells adjacent to the two stem cells. In cell that have not established direct communication only the nuclei are labeled blue (DAPI).
A possible strategy for treating neurodegenerative diseases is to transplant stem cells into the brain that prevent existing nerve cells from dying.

The method has proved successful in different models, but the mechanisms behind it are still unknown.

According to one hypothesis, the stem cells mature into fully-mature neurons that communicate with the threatened brain tissue; according to another, the stem cells secrete various growth factors that affect the host neurons.

The new report, co-authored by several international research groups and lead by Karolinska Institutet, shows that stem cells transplanted into damaged or threatened nerve tissue quickly establish direct channels, called gap junctions, to the nerve cells.

Stem cells actively bring diseased neurons back from the brink via cross-talk through gap junctions, the connections between cells that allow molecular signals to pass back and forth.