Stimulation of adult neural stem cells with a novel glycolipid biosurfactant.

Glycolipids are amphipathic molecules which are highly expressed on cell membranes in skin and brain where they mediate several key cellular processes. Neural stem cells are defined as undifferentiated, proliferative, multipotential cells with extensive self-renewal and are responsive to brain injury. Di-rhamnolipid: α-L-rhamnopyranosyl-(1-2)α-L-rhamnopyranosyl-3-hydroxydecanoyl-3-hydroxydecanoic acid, also referred to as di-rhamnolipid BAC-3, is a glycolipid isolated from the bacteria Pseudomonas aeruginosa. In the previous studies, di-rhamnolipid enhanced dermal tissue healing and regeneration. The present study provides the first assessment of di-rhamnolipid, and glycolipid biosurfactants in general, on the nervous system. Treatment of neural stem cells isolated from the lateral ventricle of adult mice and cultured in defined media containing growth factors at 0.5 and 1 μg/ml of di-rhamnolipid increased the number of neurospheres (2.7- and 2.8-fold, respectively) compared to controls and this effect remained even after passaging in the absence of di-rhamnolipid. In addition, neural stem cells treated with di-rhamnolipid at 50 and 100 μg/ml in defined media supplemented with fetal calf serum and without growth factors exhibited increased cell viability, indicating an interaction between di-rhamnolipid and serum components in the regulation of neural stem cells and neuroprogenitors. Intracerebroventricular administration of di-rhamnolipid at 300 and 120 ng/day increased the number of neurospheres (1.3- and 1.63-fold, respectively) that could be derived from the anterior lateral ventricles of adult mice. These results indicate that di-rhamnolipid stimulates proliferation of neural stem cells and increases their endogenous pools which may have therapeutic potential in managing neurodegenerative or neuropsychiatric disorders and promoting nervous tissue regeneration following injury.