Objective: To study the effect of platelet-derived growth factor-BB (PDGF-BB) gene transfected rat tendon cells on the healing and adhesion of rat tendon.
Methods: A model of heel tendon injury was reproduced in 90 rats. They were randomly divided into three groups: experiment group [with injection of 20 µL rat tendon cells (1 × 10(8) cell/mL) transfected with PDGF-BB gene into the injured tendon ends], control group [with injection of 20 µL non-transfected rat tendon cells (1 × 10(8) cell/mL) into the injured tendon ends], and blank control group (without treatment), with 30 rats in each group. Heel tendon ends were sutured with 6-0 thread by modified Kessler method and immobilized with tube-type plaster of Paris cast for one week. Rat tendon cells transfected with PDGF-BB gene were identified with gene sequencing and RT-PCR. Tendon tissue sample was harvested 3 days or 1, 2, 4, 8 week(s) after operation (POD or POW) for morphology and histology observation, and bio-mechanical test. The degree of tendon adhesion, the number of Fb and collagen fiber content in tissue, maximum tensile strength and sliding distance of tendon, and concentration of PDGF-BB in tendon tissue among groups were compared. Data were processed with t test.
Results: (1) PDGF-BB mRNA expressed stably in PDGF-BB gene transfected tendon cells as testified by RT-PCR and gene sequencing. (2) Obvious edema and inflammatory cells infiltration were observed in each group on POD 3, but they were less pronounced in experiment group. And the changes in all groups were ameliorated gradually. The difference in grading of tendon adhesion was not obvious among groups in POW 4 and 8. (3) Fb number in experiment group in POW 2, 4, 8 was respectively fewer than that of control group and blank control group (with t value respectively 2.94, 4.26, 5.76 and 4.00, 3.83, 6.12, P < 0.05 or P < 0.01). (4) Collagen fiber content in rat tendon of experimental group in POW 4 was (43 ± 6)%, which was significantly lower as compared with that of control group [(55 ± 8)%] and blank control group [(61 ± 8)%] (with t value respectively 2.94 and 4.41, P < 0.05 or P < 0.01). (5) The largest sliding distance of tendon in experiment group in POW 4 and 8 were (3.25 ± 0.33) and (3.65 ± 0.21) mm, which were significantly longer than those in control group [(2.29 ± 0.40), (2.21 ± 0.37) mm] and blank control group [(2.01 ± 0.23), (1.89 ± 0.24) mm] (with t value respectively 4.53, 8.29 and 7.55, 13.52, P values all below 0.01). There was no statistical significant difference among the three groups in the maximum tensile strength of tendon (with t value respectively 0.41, 0.41, 0.77, 0.72, P values all above 0.05). (6) Content of PDGF-BB in tendon tissue of experimental group on POD 3 and in POW 2, 4 were (12.95 ± 1.36), (8.32 ± 0.94), (9.10 ± 1.06) ng/mL, all significantly higher than those in control group [(1.13 ± 0.21), (2.07 ± 0.48), (3.85 ± 0.39) ng/mL] (with t value respectively 21.04, 14.50, 11.39, P values all below 0.01).
Conclusions: PDGF-BB gene transfected rat tendon cells can promote endogenous healing of tendon and prevent tendon adhesion.