Stem cell signals cut stroke brain damage in mice

Stem cells can promote recovery after transplantation, but not because they grow into tissue themselves. They produce a cloud of signalling proteins, growth factors and small vesicles that prompt surrounding cells to repair themselves. Researchers are now taking that a step further: they culture stem cells, collect those signals from the culture medium and use only that mixture as the treatment. This is called the stem cell secretome.

In this study, the secretome of dental pulp stem cells (stem cells from the soft core of teeth) was tested in mice that had experienced an ischaemic stroke. The treatment reduced the zone of dead brain tissue and decreased inflammation and cell death in the cerebral cortex and hippocampus. The formation of new nerve cells in the hippocampus, a region strongly involved in memory, also improved.

What the secretome does in the brain

Protein analysis of the secretome revealed several active components: proteins that reduce oxidative stress (including SOD2 and GSR), and substances that steer the activity of immune cells in the brain (microglia) toward a less aggressive profile. Signalling pathways involved in cell protection, blood vessel repair and connections between nerve cells also appeared to be affected by the treatment.

After treatment, the mice performed better on tests of motor coordination, spatial memory and contextual memory, functions that are often severely impaired after a stroke.

From cell-based to cell-free therapy

Using the secretome instead of the stem cells themselves has practical advantages. Stem cell transplantations are complex and expensive. A cell-free product is easier to standardise, store and produce at scale. The research is still in the animal experimental phase. The results were published in the journal Advanced Science. Whether this approach also works in humans remains to be demonstrated.

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