FIG. 7.

Modified MSCs are located in the implanted sponge and the tendon-like tissue surrounding the implant expresses collagen III, an early marker of fibroblastic tendon-like tissue formation. Immunofluorescence analysis was performed as described in “Materials and Methods” section. Red fluorescence: collagen III. Green fluorescence: GFP. Blue fluorescence: 4′,6-diamidino-2-phenylindole (DAPI). Left upper panel: overview of implant and its surrounding tissue. The border of the implant is indicated with a dashed white line. Two yellow rectangles (I, II) indicate regions shown in more detail. Right lower panels: individual immunofluorescence analyses show GFP and collagen III expression and DAPI staining of the implant and its immediate neighborhood (region I). GFP-expressing cells are only found in the implant. Upper right panel: merging of the individual fluorescence analyses (region I) indicates that MSCs remain in the sponge and are not directly involved in tendon differentiation. Left lower panels: individual immunofluorescence analyses do not show GFP-expressing MSCs and indicate collagen III expression and DAPI staining in a tendon-like tissue (region II). Lower middle panel: merging of the individual fluorescence analyses (region II). Tenogenic collagen III is detected in tendon-like tissue. The HE staining of this region is seen in Fig. 5C. Color images available online at www.liebertpub.com/scd