BACKGROUND: We have paid more
attention on the effects of
growth factors on
tendon healing and adhesion formation, especially on the correlation of
transforming growth factor with
tissue adhesion and
scar formation.
OBJECTIVE: To investigate the expression of
transforming growth factor beta -1
mRNA in the zone Ⅱ flexor
tendon of
wound -healing
rabbit models.
DESIGN: Randomized controlled
animal study.
SETTING: Department of Orthopaedics, Affiliated
Hospital of Medical College, Qingdao
University . MATERIALS Sixty clean
adult New Zealand white rabbits weighting 4.0-4.5 kg, of either
sex , were provided by Qingdao
Animal Experimental Center. Left
forelimbs of each
animal were as experimental side, and right
forelimbs of each
animal were as control. There were 6
time points, namely at days 1, 7, 14, 21, 28 and 56, 10
rabbits in each
time point. Of the 10
rabbits , 6
rabbits received the
in situ hybridization and 4
rabbits received the immunohistochemical
staining .
Animal intervention met the
animal ethical standard.
METHODS: Experiments were performed at the
Animal Experimental Center of
Hospital Affiliated to Medical College of Qingdao
University from September 2005 to July 2006. After
anesthesia , each
rabbit underwent complete transection of the profundus middle flexor
tendon in zone Ⅱ, and then the
tendon was repaired by the Kessler
method .
Rabbits in the
control group did not receive any intervention.
Rabbits were anesthetized and killed 1, 7, 14, 21, 28 and 56 days after the
surgery .
Skin was incised along the original incision at the experimental sides to obtain
tendons and
tendon sheaths. The same measurements were performed in the
control group . MAIN OUTCOME
MEASURES: Tenocytes and
tendon sheath
cells were detected with the
in situ hybridization and the immunohistochemical
staining to observe the expression of
transforming growth factor beta -1.
RESULTS: Sixty
rabbits were involved in the result
analysis . ①The
in situ hybridization results: Expression of
transforming growth factor beta -1
mRNA was increased at day 1 after
tendon injury in the experimental group, reached a peak at days 14-21 after
tendon injury , reduced at day 28 and was still in a high level at day 56. Expression of
transforming growth factor beta -1
mRNA was high in
tendon sheath
cells around the repaired region. At the same
time point, the expression of
transforming growth factor beta -1
mRNA was higher in
tendon sheath
cells than in
tenocytes . Low expression of
transforming growth factor beta -1
mRNA was found in
tenocytes and
tendon sheath
cells in the
control group . The expression of
transforming growth factor beta -1
mRNA in
tenocytes and
tendon sheath
cells was higher in the experimental group than in the
control group at each
time point (P < 0.05). ②Immunohistochemical
staining results: Expression of
transforming growth factor beta -1
protein was elevated at day 1 after the
surgery , reached the peak at days 14-21 and was still in a high level at day 56 in the experimental group. Low expression of
transforming growth factor beta -1
protein was seen in the
control group .
CONCLUSION: The normal uninjured
tenocytes and
tendon sheath
cells produce
transforming growth factor beta -1. The
cytokine is activated in the injured
tendon . The increase of this
cytokine in both
tenocytes and
tendon sheath
fibroblasts are coincidence with both extrinsic and intrinsic mechanisms for
tendon repair.