In vitro modulation of gamma amino butyric acid (GABA) receptor expression by bone marrow stromal cells

Bone marrow stromal cells (BMSC) have the capability to undergo a change of morphology, reminiscent of neuronal cells, after exposure to an inductive medium. These induced BMSC-derived neuron-like (BDNL) cells express several neuronal markers, including Microtubule-Associated Protein Tau, Neurofilament M, and Nestin as revealed by immunocytochemistry analysis. To assess whether the induction process has possible functional relevance, we have focused our attention on the expression of neurotransmitter receptors. In particular, we show that the expression of GABA_A subunits α1, β2/3, ε and GABA_B1 mRNAs is greatly enhanced in BMSC by the induction treatment. Similar results were obtained from rat skin fibroblasts subjected to the same induction protocol, with the exception for the GABA_B2 transcript that was expressed only by BMSC and BDNL. The presence of both GABA_B1 and GABA_B2 subunits in BDNL cells suggests that functional GABA_B receptors might be assembled: we indeed found that a functional GABA_B receptor, negatively linked to cyclic AMP production, is expressed in BDNL. Therefore, we suggest that BMSC can be converted into cells equipped with appropriate receptors coupled to transduction mechanisms, potentially responding to a specific neurotransmitter.