Comparative proteomic analysis of serum proteins after long bone fracture complicated with severe traumatic brain injury

Objective To screen the protein that may enhance osteogenesis from the differential serum proteins following long bone fracture (LBF) complicated with severe traumatic brain injury (TBI). Methods Three patients with lower limb LBF complicated with severe TBI were randomly selected as the experimental group (group IF). They were matched with 3 patients with pure severe TBI and 3 patients with pure lower limb LBF fracture as 2 control groups (group I and group F, respectively). All the patients in the 3 groups were similar in general conditions. Their serum samples were collected 3 days after injury in each group. The samples were treated with kits to remove abundant proteins which were purified and quantitatively analyzed. Then 2-DE and MALDI-TOF-MS were conducted to identify the differential protein spots that up-regulated more than 3 times in the experimental group compared with the controls. Results Sixteen protein spots were identified which were differential between group IF and group I. Of these 16 significant spots, 4 were only expressed in group IF, 5 were up-regulated and 7 down-regulated. Up-regulated spots were identified to 5 unique proteins by MALDI-TOF-MS, and spots 393 and 423 expressed merely in group IF were identified as serotransferrin. Seventeen protein spots were identified which were differential between group IF and group F. Of these 17 significant spots, 2 were only expressed in group IF, 8 were up-regulated and 7 down-regulated. Up-regulated spots were identified to 4 unique proteins by MALDI-TOF-MS, and 5 significantly increased spots were also identified as serotransferrin. Conclusion It is preliminary ascertained that serotransferrin may be closely related to the mechanism that severe TBI promotes bone-forming. Key words: Fractures, bone; Proteome; Immunoelectrophoresis, two-dimensional; Traumatic brain injury; Mass spectrometry analysis