Rabbit LMSCs were isolated from the upper labial mucosa, whereas human LMSCs were isolated from the lower labial mucosa according to the following protocol. Briefly, small samples (5 × 10 mm; 0.4 mm in a depth) of labial mucosa were mechanically dissected using no. 15 Bard Parker blade, washed 3 times with phosphate buffered saline (PBS) containing antibiotics (250 µg/mL gentamicin; 1000 U/mL Pen/Strep; Life Technologies, Carlsbad, CA, USA), and incubated in enzyme solution (5 mg/mL Dispase II; 12 mg/mL Collagenase type I; Sigma-Aldrich, St. Louis, MO, USA) in an ES-20 Orbital Shaker-Incubator (Biosan, Riga, Latvia) at 37°С for 40 minutes. Samples then were treated with 0.25% trypsin-EDTA (Life Technologies) at 37°С for 20 minutes, centrifuged for 7 minutes at 1200 × g, and the final cell suspension was plated in a culture dish. The labial mucosa-derived cells were cultured in DMEM/F-12 medium (Life Technologies) supplemented with 10% of fetal bovine serum (FBS; Cytiva, Marlborough, MA, USA), 1000 U/mL Pen/Strep (Life Technologies), and 0.5 ng/mL amphotericin B (Thermo Scientific, Waltham, MA, USA) in an incubator at 37°С, 5% CO2, and 95% humidity. One to 2 weeks after isolation, both rLMSCs and hLMSCs were tested for mycoplasma contamination. After reaching 70% to 80% confluency, cells were passaged using 0.25% trypsin-EDTA for 3 minutes at 37°С and cultured up to passage 6 for further in vitro or in vivo studies.