Fig. 5

Proliferative human cells were detected in the rat knee joint tissues. a Human skin tissues were used for positive (with monoclonal antihuman mitochondria antibody) and negative (IgG isotype) IHC staining controls. Positive signals were detected in both nonsurgery and surgery groups with human adipose-derived mesenchymal stem cell (haMSC) treatment, but not in the free DiD group (no haMSC treatment). The human cells were mainly detected in the rat meniscus and cartilage. b Human hepatocellular carcinoma cell line HepG2 were used for positive and negative controls with regard to a monoclonal antihuman ki67 antibody IHC staining. Human cells undergoing proliferation were detected in the positive control as well as in the joint tissues of the DiD-labeled haMSC treatment groups, but not in the free DiD group. Samples of the surgery group (n = 2) and the nonsurgery group (n = 2) were both collected at the end of the experiments (day 70 and day 28), respectively