title: Evaluation of the proliferation and viability rates of nucleus pulposus cells of human intervertebral disk in fabricated chitosan-gelatin scaffolds by freeze drying and freeze gelation methods.
abstract: BACKGROUND
  Low back pain is one of the most significant musculoskeletal diseases of our time. Intervertebral disk herniation and central degeneration of the disk are two major reasons for low back pain, which occur because of structural impairment of the disk. The reduction of cell count and extracellular matrix, especially in the nucleus pulposus, causes disk degeneration. Different scaffolds have been used for tissue repairing and regeneration of the intervertebral disk in tissue engineering. Various methods are used for fabrication of the porosity scaffolds in tissue engineering. The freeze drying method has disadvantages such as: It is time consuming, needs high energy, and so on. The freeze-gelation method can save a great deal of time and energy, and large-sized porous scaffolds can be fabricated by this method. In this study, proliferation of the nucleus pulposus (NP) cells of the human intervertebral disk are compromised in the fabricated Chitosan-gelatin scaffolds by freeze drying and freeze gelation methods.
  
  
  METHODS
  The cells were obtained from the nucleus pulposus by collagenase enzymatic hydrolysis. They were obtained from patients who were undergoing open surgery for discectomy in the Isfahan Alzahra Hospital. Chitosan was blended with gelatin. Chitosan polymer, solution after freezing at -80°C, was immersed in sodium hydroxide (NaOH) solution. The cellular suspension was transferred to each scaffold and cultured in plate for 14 days. Cell viability and proliferation were investigated by Trypan blue and MTT assays.
  
  
  RESULTS
  The MTT and Trypan blue assays demonstrated that cell viability and the mean of the cell number showed a significant difference between three and fourteen days, in both scaffolds. Accordingly, there was a significantly decrease in the fabricated chitosan-gelatin scaffold by the freeze-drying method.
  
  
  CONCLUSIONS
  The fabricated chitosan-gelatin scaffold by the freeze-gelation method prepared a better condition for proliferation of NP cells when compared with the fabricated chitosan-gelatin scaffold by the freeze drying method.
authors.affiliation: Student of Medicine, School of Medicine and Student Research Committee, Isfahan University of Medical Sciences, Isfahan, Tehran, Iran.
authors.forename: Zeinab
authors.initials: Z
authors.lastname: Karimi
authors.affiliation: Applied Biotechnology Researches Center, Pajooheshgah, Baqiatallah University of Medical Sciences, Tehran, Iran; Department of Tissue Engineering and Applied Cell Sciences, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Masoud
authors.initials: M
authors.lastname: Ghorbani
authors.affiliation: Department of Anatomy and Molecular Biology, Medicine School, Isfahan University of Medical Sciences, Tehran, Iran.
authors.forename: Batool
authors.initials: B
authors.lastname: Hashemibeni
authors.affiliation: Department of Anatomy and Molecular Biology, Medicine School, Isfahan University of Medical Sciences, Tehran, Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Bahramian
keywords: Chitosan; freeze drying; freeze gelation; gelatin; intervertebral disk