[EFFECT OF ADIPOSE-DERIVED STEM CELLS COMBINED WITH CHITOSAN ON IMMEDIATE RETRACTION RATE OF EXPANDED SKIN IN RABBIT].

Objective: To investigate the effect of adipose-derived stem cells (ADSCs) combined with chitosan on the immediate retraction rate of rabbit expanded skin.
Methods: ADSCs were isolated from rabbit fresh fat under sterile conditions and cultured to the 3rd generation by methods of enzymatic digestion; the specific surface markers and the differentiation into epidermal cells and cartilage cells were identified. Forty New Zealand white rabbits (aged, 2-3 months) were randomly divided into 4 groups (n = 10): control group (group A), ADSCs group (group B), chitosan group (group C), and ADSCs+chitosan group (group D). ADSCs cell suspension with the concentration of 5 x 10⁶ cells/mL was prepared. The skin expansion model was made by embedding 30 mL dilator into the back of rabbit. Chitosan (2%, 5 mL) was coated on the surface of the dilator in groups C and D, and ADSCs cell suspension (1 mL) was injected into the skin in groups B and D. Conventional tissue expansion was performed to expected capacity at 4 weeks, and maintained for 1 week. The expanded skin was harvested to measure the immediate retraction rate, and the thickness of skin, epidermis, and fibrous capsule with HE staining. Masson staining was used to observe the characteristics of collagen in the fibrous capsule, and immunohistochemical staining for CD31 to determine the microvessel density (MVD).
Results: ADSCs were successfully isolated, and had multiple differentiation ability. All the animals survived to the end of the experiment. The immediare retraction rate of group D was significantly lower than that of the other groups (P < 0.05), groups B and C were significantly lower than group A (P < 0.05), and group B was significantly lower than group C (P < 0.05). The histological staining revealed that there were more mature fibroblasts and coarse collagen fibers with regular arrangement in groups A and B; there were more naive fibroblasts and tiny and sparse collagen fibers in groups C and D. The thickness of skin and epidermis, and MVD of groups B and D were significantly larger than those of groups A and C (P < 0.05); the thickness of fibrous capsule of groups C and D was significantly less than that of groups A and B (P < 0.05); but no significant difference was found in the above indexes between other groups (P > 0.05).
Conclusion: ADSCs can promote angiogenesis and regeneration of the expanded skin, have no effect on the fibrous capsule. Chitosan can inhibit the proliferation of fibrous capsule, so a combination of ADSCs and chitosan can inhibit the immediate retraction of the expanded skin.