Soft tissue augmentation with injectable materials has been a challenging problem for plastic and reconstructive surgeons. Although filler materials have been used for soft tissue augmentation, adverse effects such as inflammation, distortion, and repeated procedures due to absorption still exist. In this study, biologic filler containing human fibroblasts and placenta extracts was developed to overcome these problems as a concept of cell therapy.In an in vivo assay, 40 nude mice were divided into 4 groups: 1 control group and 3 experimental groups. Biologic fillers containing human fibroblasts untreated (control), cultured with 0.1% placenta extract (group 1), cultured with 10% fetal bovine serum (group 2), and cultured with both 0.1% placenta extract and 10% fetal bovine serum (group 3) were used in each groups. Cultured human fibroblasts were injected into the back of each mouse with fibrin glue to maintain the shape and volume. These groups were compared during an 8-week period. The gross, histologic, and biomolecular studies were proceeded to evaluate the effect of biologic filler.In geometric maintenance, volumes in experimental groups were 1.6 (group 1), 1.2 (group 2), and 1.9 times (group 3) more reserved than that in the untreated control group (control) at 8 weeks. In histology, abundant proliferation of fibroblasts as well as extracellular matrices including collagen and glycosaminoglycan was visualized in experimental groups. Enzyme-linked immunosorbent assay was used to analyze collagen and glycosaminoglycan, and reverse transcription-polymerase chain reaction was used to analyze the messenger RNA expression of COL1A1, a gene for collagen type 1, which shows a significant difference between control and experimental groups. There is no statistically significant difference between groups 1 and 2; on the other hand, group 3 statistically has the best outcome among the experimental groups.