Human Amnion-Derived Mesenchymal Stem Cells Prolong Graft Survival in a Rat Hind Limb Allotransplantation Model

Recently, the immunomodulatory effects of mesenchymal stem cells have been reported in several studies. The purpose of this study was to evaluate the effect of the administration of human amnion-derived mesenchymal stem cells (hAm-MSCs) in a rat vascularized composite allotransplantation model.

A total of 18 Lewis (LEW) rats and 6 Brown-Norway (BN) rats were used. Sixteen LEW rats as recipients were divided randomly into four groups: Isograft (Iso), Untreated (UT), FK, and MSC groups (n = 4, each group). Hind limb transplantation was performed. In the Iso group, 2 LEW rats were used as donors. In the other groups, 6 BN rats were used as donors. In the UT group, no immunosuppressant was used. In the FK group, 0.2 mg/kg/day of FK506 (tacrolimus) was administered from day 0 to day 6. In the MSC group, 2 × 10⁶ hAm-MSCs were administered on day 7 after tacrolimus administration (day 0-6). Graft survival was assessed by daily inspection, histology, and immunohistology with the TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling) assay. Cytokine mRNA expression analysis using real-time, reverse transcription PCR (RT-PCR) of the grafts was analyzed.

Graft survival in the MSC group (14.8 days) was significantly prolonged compared with that of the FK group (13 days; p < 0.05). Histology and immunohistology with the TUNEL assay showed a significant reduction of mononuclear cell infiltration and apoptotic cells in the MSC group compared with the FK group (p < 0.05). RT-PCR analysis of cytokine mRNA expression showed a significant decrease of IL-2 and an increase of TGFβ in graft muscle (p < 0.05).

hAm-MSCs prolonged graft survival in the rat vascularized composite allotransplantation model. hAm-MSCs could be an alternative immunomodulatory agent to avoid the side effects of conventional immunosuppressant.