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Figure 1: Human umbilical cord blood-derived mesenchymal stem cells (MSCs), polydeoxyribonucleotide (PDRN), and ultrasound images. (a) PDRN. (b) MSCs. (c) Injection was made in the left shoulder subscapularis full-thickness tears under ultrasound guidance. (d) Longitudinal ultrasound image shows the needle (arrow) in the left shoulder subscapularis of the rabbit. T: tendon; I: injectant.