1. Department of Bioengineering, College of Life Science, Northeast Agricultural University, Harbin, Heilongjiang 150030, P.R. China
2. Department of Neurosurgery, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150001, P.R. China
3. Department of Neurosurgery, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang 150081, P.R. China