Abstract: Objective Using shotgun mass spectrometry to detect proteins probably contained in bone marrow stromal cells(BMSCs) conditioned medium. Methods Mixed with BMSCs conditioned medium was divided into two parts which is(>5kD and <5kD) by means of ultrafiltration. The two parts were used to culture neural stem cells(NSCs) separately, and the proportions of neurons, astrocytes and oligodendrocytes in the offsprings of NSCs were calculated, then the effective part that could regulate the differentiation of NSCs was detected by Shotgun mass spectrometry. Results The BMSCs conditioned medium which is >5kD could promote the NSCs differentiate into more neurons and oligodendrocytes. The SDS-PAGE of this part showed that the most proteins were above 14kD, then the protein bands were enzymed. In total, 456 proteins were identified by Shotgun mass spectrometry after all the protein bands were enzymed, there were 154 similar proteins, 17 hypothetical proteins and 56 unknown proteins. And in the rest of 229 proteins, most of them were cytoskeletal proteins, secreted proteins, signal transduction proteins, enzymes, transporter and so on. Conclusion Many proteins secreted by BMSCs could regulate the differentiation of NSCs so as to prove the protein components probably existed in the BMSCs conditioned medium.

Key words: Bone marrow stromal cells, Neural stem cells, Shotgun proteomics