title: Effect of local treatment with adipose tissue-derived mesenchymal stem cells in the early tumorigenesis of osteosarcoma.
abstract: There are conflicting data describing the effect of mesenchymal stem cells (MSCs) on tumorigenesis. The present study aimed to determine the survival rate and effect of adipose tissue-derived MSCs (ADMSCs) in tumor growth using bioluminescence imaging (BLI) and ultrasound (US) in an osteosarcoma xenograft model. Firefly luciferase-expressing ADMSCs combined with the osteosarcoma cell line UMR-106 in 4 different proportions (5, 10, 15 and 25%, named G1-G4, respectively) were xenografted into the right flanks of nude mice. The same number of UMR-106 cells was inoculated into the contralateral side of each mouse. Serial bioluminescence images were captured over 16 days to monitor the presence of ADMSCs in each group of 5 animals. The tumor volume was measured by ultra-high resolution US, and the tumor volume ratio (AMDSC mixed xenograft/control xenograft) was obtained to evaluate the effect of AMDSCs on tumor growth. Immunohistochemistry was performed to confirm the distribution of residual AMDSCs in the tumor. In G1, G2 and G3, the suppression of tumor growth by AMDSCs was noted in 2/5, 4/5 and 4/5 mice, respectively. However, accelerated tumor growth was noted in G4, which had the highest proportion of ADMSCs. The tumor volume ratio was significantly lower in G2 and G3 compared to G4, by Mann-Whitney U test (P=0.0159). Bioluminescence images demonstrated a serial decrement of the reporter gene for ADMSCs in the tumor mass without evidence of proliferation. Immunohistochemistry staining revealed minimal residual ADMSCs in the tumor periphery. Taken together, our data revealed that direct inoculation of ADMSCs into a tumor xenograft caused the death of the majority of ADMSCs in the tumor mass. Furthermore, relatively low proportions of ADMSCs suppressed the growth of osteosarcoma, while higher proportions showed a tumor-promoting effect.
authors.affiliation: Department of Radiology, Gil Hospital, Gachon University School of Medicine and Science, Incheon 406‑799, Republic of Korea.
authors.forename: Sheen-Woo
authors.initials: SW
authors.lastname: Lee
authors.affiliation: Department of Nuclear Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul 135-720, Republic of Korea.
authors.forename: Tae Joo
authors.initials: TJ
authors.lastname: Jeon
authors.affiliation: Department of Radiology, Stanford University School of Medicine, Stanford, CA 94305-5105, USA.
authors.forename: Sandip
authors.initials: S
authors.lastname: Biswal
mesh_terms: D000273:Adipose Tissue / Q000166:cytology; D000818:Animals; D001859:Bone Neoplasms / Q000628:therapy*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D064987:Cell- and Tissue-Based Therapy; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells; D051379:Mice; D008819:Mice, Nude; D008822:Mice, Transgenic; D009368:Neoplasm Transplantation; D012516:Osteosarcoma / Q000628:therapy*; D051381:Rats; D014183:Transplantation, Heterologous; D047368:Tumor Burden