Tat-MyoD fused proteins, together with C2c12 conditioned medium, are able to induce equine adult mesenchimal stem cells towards the myogenic fate.

The Tat protein is able to translocate through the plasma membrane and when it is fused with other peptides may acts as a protein transduction system. This ability appears particularly interesting to induce tissue-specific differentiation when the Tat protein is associated to transcription factors. In the present work, the potential of the complex Tat-MyoD in inducing equine peripheral blood mesenchymal stem cells (PB-MSCs) towards the myogenic fate, was evaluated. Results showed that the internalization process of Tat-MyoD happens only in serum free conditions and that the nuclear localization of the fused complex is observed after 15 hours of incubation. However, the supplement of Tat-MyoD only was not sufficient to induce myogenesis and, therefore, in order to achieve the myogenic differentiation of PB-MSCs, conditioned medium from C2C12 cells was added without direct contact. Real Time PCR and immunofluorescence methods evaluated the establishment of a myogenic program. Our results suggest that TAT- transduction of Tat-MyoD, when supported by conditioned medium, represents a useful methodology to induce myogenic differentiation.