Effects of microencapsulated rabbit Schwann cell transplantation on myelin sheath regeneration in rats with spinal cord injury / 中国组织工程研究

ABSTRACT

BACKGROUND: Schwann cells play an important role in axonal growth and myelin sheath formation of the peripheral nerve. Whether Schwann cells play the same role in the spinal cord had attracted considerable attention. Microencapsulation technology as an effective immune isolation technique can effectively keep Schwann cell activity to play the repair effect of Schwann cell in the spinal cord.OBJECTIVE: To observe the changes of myelin sheath in the injured transection of rats after transplantation of the alginic acid microencapsulated Schwann cells.DESIGN, TIME AND SETTING: The randomized controlled animal experiment was performed at the Basic Medical School of Nanchang University from March 2005 to February 2008.MATERIALS Sciatic nerve trunk was obtained from adult rabbits to harvest Schwann cells in vitro using repeatedly differential velocity adherent technique, and to prepare Schwann cell suspension and microencapsulated Schwann cell suspension.METHODS: A total of 146 adult Sprague Dawley rats were used to establish models of right hemi-transection damage at T_(10) level and randomly assigned to four groups simple injury group (n=44), cell transplantation group (n=44), microencapsulated cell transplantation group (n=44) and normal control group (n=14). At 1, 3, 7,14 and 28 days following surgery, 8 rats were selected from each group at each time point (2 from the normal control group) for perfusion and fixation. Spinal cord tissue was collected to make paraffin section, and then subjected to hematoxylin-eosin staining and Loyez myelin staining. In addition, 2 rats were selected from each group at 2 and 8 weeks. The spinal cord tissue was fixed, embedded in Epon816, stained using uranyl acetate and aluminum citrate, and then observed using an electron microscope.MAIN OUTCOME MEASURES: Neuron number and survival were observed surrounding the damaged region. Structural changes in the myelin sheath from spinal cord white substance at the damage site were measured.RESULTS: At 1 and 3 days following spinal cord injury, spinal neurons were degenerated and necrotic at damaged site, with reduced number of myelin sheath, loose structure, but above-mentioned was rare in the cell transplantation and microencapsulated cell transplantation groups. At 7 days, the reduced number of myelin sheath, with damaged structure was seen. The microencapsulated cell transplantation group was light. At 14 days, number of neurons was increased, with increased cell body, especially in the microencapsulated cell transplantation group. At 28 days, neurons gradually recovered, myelin sheath was gradually complete, with increased number in the microencapsulated cell transplantation group. There were significant differences compared with the simple injury and cell transplantation groups (P < 0.01). At 8 weeks, abundant myelin sheath was repaired, with new myelin sheath in the microencapsulated cell transplantation group.CONCLUSION: Microcapsule has immune isolation effects. Microencapsulated rabbit Schwann cells can promote the repair of rat spinal cord neurons and axonal myelinization.