Electroacupuncture Promotes CNS-Dependent Release of Mesenchymal Stem Cells.

The authors report interesting findings that electro-acupuncture (EA) in humans and rats mobilizes mesenchymal stem cells (MSCs) into the circulation, an effect that was closely related to sympathetic activation because it was mimicked by disinhibition of the hypothalamus and administration of epinephrine or dopamine in rats. Importantly, the mobilization of MSCs by EA correlated with pain attenuation in rats with tendon injury. This finding points to a novel direction in the search for mechanisms of EA analgesia. While EA also induced anti-inflammatory cytokines and activated medium- to large-diameter primary sensory neurons, which is expected, the finding of EA-induced MSC release will lead to further studies addressing EA-nervous system interactions and immune regulation of pain.

The source of EA-mobilized MSCs requires further study, although they were shown to be adipogenic. They do not appear to be from bone marrow or adipose tissue since distinct phenotypes were observed between bone marrow-, adipose tissue-, and EA-MSCs. In general, many MSCs reside in perivascular niches, and they are very likely to be released by sympathetic activation. The authors show that EA apparently mobilized CD34+ cells, suggesting that a subtype of primitive hematopoietic stem cell was EA responsive. We cannot relate these cells to mesenchymal stromal cells that have been shown to produce pain relief, since those cells are CD34-. From a mechanistic and therapeutic point of view, it would be interesting to know whether cells isolated from EA-treated animals produce analgesia in other animal models.