β-PIX is critical for transplanted mesenchymal stromal cell migration

Bone marrow-derived mesenchymal stromal cells (MSCs) have been used successfully as a source of stem cells for treating neurodegenerative diseases. However, for reasons that are not clear, autologous MSC transplants have not yielded successful results in human trials. To test one possible reason, we compared the migratory ability of MSCs from amyotrophic lateral sclerosis (ALS) patients with those of healthy controls. We found that MSCs derived from ALS patients (ALS-MSCs) had a reduced ability to migrate, which may explain why autologous transplantation is not successful. We also found that expression of one of the intracellular factors implicated in migration, β-PIX, was significantly reduced in ALS-MSCs compared with healthy stem cells. Restoration of β-PIX expression by genetic manipulation restored the migratory ability of ALS-MSCs, and inhibition of β-PIX expression with shRNA reduced the migration of healthy MSCs. We suggest that transplantation of allogeneic or genetically modified autologous stem cells might be a more promising strategy for ALS patients than transplantation of autologous stem cells.