BACKGROUND: Live autologous cultured fibroblasts improve sagging and wrinkles when injected into the dermis; however, their diversity and differences in efficacy depending on the skin layer to which they are transplanted remain unclear. This study investigated the behavior and effects of dermal- and fascial-derived fibroblasts from mouse fetuses on the dermis and fascia. METHODS: The collagen-producing capacity of fibroblasts from the shallow (dermis) and deep (fascia) skin layers of fetal and adult C57BL/6-Tg(CAG-EGFP) mice was compared using western blotting and real-time polymerase chain reaction. Contractile capacity was investigated using a collagen contractility assay and an ex vivo mouse skin model. We transplanted these cells into the shallow and deep layers of the back skin of aged C57BL/6 mice and observed the engraftment rate and histological changes in the skin. The anti-inflammatory effects of these cells were also compared. RESULTS: Fascial fibroblasts from embryonic day 17 fetal mice exhibited higher collagen production and contractile capacity than papillary fibroblasts from adult mice. The transplanted fascial and dermal cells showed high engraftment rates in the deep and shallow (injected near the layer from which they were derived) layers, respectively. Collagen fiber density was highest when embryonic day 17 fascial fibroblasts were transplanted into the deep layer, and an anti-inflammatory effect was observed. CONCLUSIONS: Dermal fibroblast transplantation improves the phenotype of aging skin via collagen synthesis and contraction, with greater efficacy when transplanted into a layer consistent with the skin layer from which the primary cells are harvested.