[Preliminary study on stromal vascular fraction promoting angiogenesis and tissue regeneration in tissue engineering chamber].

OBJECTIVE: To evaluate the mechanism of stromal vascular fraction (SVF) promoting angiogenesis and tissue regeneration in tissue engineering chamber. METHODS: Twenty-four 6-month-old New Zealand white rabbits, male or female, weighing 2.5-2.8 kg, were selected. Thoracic dorsal arteriovenous bundle combined with collagen type I scaffold was transplanted to dorsal side, and wrapped by cylindrical hollow silicone chamber; all animals were randomly divided into the experimental group (n = 12) and the control group (n = 12). SVF was isolated from the back fat pads of rabbits in experimental group and labelled with DiI at 2 weeks after operation. The 1 mL cell suspension (1 x 10(6) cells/mL) and equal saline were injected into the chamber in experimental group and control group, respectively. The regenerative tissues were harvested for general observation and HE staining at 2 and 4 weeks after injection: and immunofluorescent staining was carried out in experimental group at 4 weeks. RESULTS: At 2 weeks after injection, the regenerative tissue was cylindrical; obvious vessel network and incompletely degradable collagen scaffold could be seen on the surface of the new tissue in 2 groups. The volume of new tissue was (0.87 +/- 0.11) mL in experimental group, and (0.72 +/- 0.08) mL in control group at 2 weeks, showing significant difference (t = 2.701, P = 0.011). At 4 weeks, little collagen scaffold could be seen on the surface in control group, but no collagen scaffold in experimental group; the volume of new tissue was (0.74 +/- 0.14) mL in experimental group, and (0.64 +/- 0.10) mL in control group, showing no significant difference (t = 1.424, P = 0.093). HE staining showed new mature vessels at 4 weeks, but no adipose tissue or fat lobulus formed in both groups; the capillary density was significantly higher in experimental group than in control group at 2 weeks (t = 6.291, P = 0.000) and at 4 weeks (t = 5.445, P = 0.000). The immunofluorescent staining found that SVF survived and located at the edge area after 4 weeks; the expressions of CD31 and DiI were positive in some endothelial cells. CONCLUSION: SVF can promote the angiogenesis and tissue regeneration in tissue engineering chamber, but it can not differentiate into adipocyte spontaneously without adipogenic microenvironment.