The Effects of Lipoaspirate-Derived Fibrous Tissue on Survival Quality and Mechanical Property of Fat Grafts.

BACKGROUND Fibrous connective tissue (referred to as fiber) in lipoaspirates would be discarded before lipotransfer in case of cannula blockage. However, the fiber contains extracellular matrix which provide structure support and is rich in stromal vascular fractions (SVFs). Removal of the fiber might theoretically affect the survival quality and mechanical properties of fat grafts. But there is few evidence in vivo and vitro about how the fiber affects the fat grafts. OBJECTIVE To assess the effect of fibers on the survival quality and mechanical property of fat grafts. METHODS The SVFs in both fat and fiber were obtained by collagenase digestion for cells counting and comparison. Three groups were designed according to the different proportions of fat and fiber: the fat group (100% fat), the mixed group (50% fat, 50% fiber in volume ratio), and the fiber group (100% fiber). Three groups of grafts were transplanted in vivo to evaluate the differences in volume retention rate, histological characteristics and mechanical properties. RESULTS The amount of SVF cells in fibers (3.47 ± 1.49 × 104 cells/mL) was significantly lower than that in fat (12.3 ± 4.95 × 104 cells/mL) (P < 0.05). Grafts in the mixed group and the fiber group showed an increase of volume retention at week 4, but the fiber content showed no significant effects on the volume retention of grafts in three groups at week 12. Elasticity modulus of grafts in the fat group was higher than that in the fiber group and the mixed group at week 4 and 8, the fiber content showed no significant effects on the elasticity modulus of grafts in three groups at week 12. The addition of the fiber reduced the inflammation, cysts, fibrosis, and capillaries density of the grafts. CONCLUSIONS There were few SVF cells in the fiber. When it was mixed with fat in different proportions and transplanted in vivo, the content of fiber showed no significantly different effects on the long-term volume retention and mechanical property of fat grafts. Due to the risk of blockage, it is recommended to discard the fiber in lipoaspirates.