Figure 4: Gross morphology of tear site at 4 weeks postinjection. FTT was observed in all eight rabbits in G1-SAL. In G2-PDRN, a PTT was observed in three rabbits and FTT in five rabbits. In G3-MSC, a PTT was observed in three rabbits, FTT in two rabbits, and CH in three rabbits. In G4-MSC + PDRN, a PTT was observed in five rabbits, FTT in one rabbit, and CH in two rabbits. SAL (normal saline 0.2 mL); PDRN (PDRN 0.2 mL); MSC (MSC 0.2 mL); and MSC + PDRN (MSC 0.2 mL with PDRN 0.2 mL). PDRN: polydeoxyribonucleotide; MSC: human umbilical cord blood-derived mesenchymal stem cell; FTT: full-thickness tendon tear; PTT: partial-thickness tendon tear; CH: nearly complete healing.