What tissue is formed after graft of adipose-derived stromal vascular fraction cells?

Cultured human fibroblasts have been used for soft-tissue augmentation in the face. However, if cultured cells are to be used clinically, the approval of the Food and Drug Administration and time-consuming culturing procedures are required. For this reason, we investigated adipose-derived stromal vascular fraction (SVF) cells, which could be obtained in large quantities without cell culture. However, unlike fibroblasts, SVF cells are a heterogenic cell population. Therefore, it was hypothesized that a SVF cell graft may possibly form various tissues. This study was performed to determine what tissue would form after a graft of SVF cells. Stromal vascular fraction cells were isolated from liposuctioned human adipose tissue. For a test group, SVF cells were suspended in hyaluronic acid filler. For a control group, no cells were included in the filler. These implants were subcutaneously injected into the backs of 4 nude mice. After 16 weeks, the injection areas were excised, and histologic examination was performed including immunohistochemistry to confirm the presence of human collagen. The test group specimens revealed fibrous connective tissues infiltrating into and surrounding the hyaluronic acids. Collagen fibers and fibroblasts were found around newly formed vascular structures. In contrast, the control group did not show cells or hyaluronic acid particles. Immunohistochemistry of the test group displayed strong expression of human collagen. However, the control group exhibited negative staining. This suggests that transplanted uncultured human SVF cells combined with hyaluronic acid filler generate fibrovascular tissue.