Cell migration after synovium graft interposition at tendon repair site

Abstract

Background: We have recently reported that interpositional synovium grafts from tendon sheath have a potential to accelerate tendon healing when implanted at the repair site. The purpose of this study was to investigate the effect of orientation of the synovium after synovium graft transplantation, by comparing the ability of cells from the visceral and parietal surfaces to migrate into the tendon in a canine tissue culture model.

Methods: The synovium graft was placed within a complete tendon laceration, with either the visceral or parietal surface facing the proximal end of the lacerated tendon. The number of migrating cells was quantified by a cell migration assay. Qualitative immunohistochemistry and confocal laser microscopy were also used at day 10.

Results: Many labeled synovial cells were observed within the tendon to which the visceral surface of the synovium graft was facing. Migrated cells were also observed on the parietal side, but there were fewer cells compared to visceral surface cells. Migrating cells all expressed α-smooth muscle actin.

Conclusion: We found that graft orientation affected cell migration. Whether this finding has clinical significance awaits in vivo study.

Keywords: Cell migration; Synovial cells; Synovium graft; Tendon healing.

Fig. 1

Dissection of dog FDP tendon and synovium. a Harvest of synovium. b Synovium graft

Fig. 2

Histology of suture site at each time point (days 1, 3, 7, and 10) without (a) or with (b) synovium graft (×10 objective magnification, scale bar, 100 μm). Left side is distal end and right side is proximal end. T, tendon end; S, synovium graft

Fig. 3

Confocal laser microscopic images of suture site at each time point, days 1, 3, 7, and 10 (×40 objective magnification, scale bar 20 μm). In each time point, a top row shows control without synovium graft. b Second row shows repair site in which visceral surface of the synovium facing to distal end of tendon. c Third row shows repair site in which parietal surface of the synovium facing to proximal end of tendon. Red color indicates synovial cells stained with CellTracker. Green color indicates α-SMA staining. Blue color indicates DAPI staining. T, tendon end; S, synovium graft

Fig. 4

Microscopic images of migrated cells at each time point, days 1, 3, 7, and 10 (×10 objective magnification, scale bar 100 μm). a Visceral surface of synovium graft is facing to the bottom. b Parietal surface of synovium graft is facing to the bottom

Fig. 5

Cell migration assay. Inside indicates that the visceral surface of the synovium graft is facing to the bottom, and outside that the parietal surface of the synovium graft is facing to the bottom. Results are presented as mean and standard deviation (SD) of n = 8. *P < 0.05 indicates a significant difference