Figure 3. Postn^Lin cells are primarily added to the pool between D7-10, and make time-dependent contributions to healing.

(A & B) Temporally-dependent contributions to the overall Postn^Lin pool were defined using four different Tmx treatment and harvest regimens. Tmx was given for two days and hind paws harvested on the third day of the regimen for immunofluorescent analysis, with the following regimens used: TMX D2 & 3, harvest D4 (blue); TMX D7 & 8, harvest D9 (red); TMX D14 & 15, harvest D16 (green); TMX D21 & 22, harvest D23 (black). Postn^Lin cells are shown in green, αSMA+ myofibroblasts in red, and nuclei are stained blue with Hoescht. Tendon ends are outlined by dotted white lines. The percent of cells in the healing tendon that were Postn^Lin-derived using each labelling regimen is quantified in (C). (D) Based on the large addition of Postn^Lin to the healing environment at this time, Postn^Lin cells were labelled via Tmx administration on D10 & 11, with tendons harvested at D28. (E) At D28, minimal overlap between this subset of Postn^Lin cells (red) and αSMA+ myofibroblasts (green) was observed, indicating this subset of Postn^Lin cells does not contribute to the persistent myofibroblast population. (F) Several Postn^Lin cells actively expressed Hsp47 at this time (white arrows), while there was also a large population of Postn^Lin cells that did not express Hsp47 (purple arrows).