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.