Figure 5.

In vitro and ex vivo MR signal of labeled and unlabeled hMSCs at 3 Tesla: (a) Axial T2-weighted MR image of 2×10⁶ hMSC in test tubes with 50μl Ficoll. Unlabeled control cells demonstrate positive (bright) T2-signal, while cells labeled with ferumoxytol in FBS, HS, and StemPro® media demonstrate negative (dark) T2-signal. (b) Corresponding T2 relaxation times show significant T2-shortening of hMSC labeled with ferumoxytol in HS-containing media compared to FBS, StemPro® media as well as protamine and protamine + heparin transfection media. Data are displayed as mean data of three experiments in each group with standard errors. (c) Representative sagittal MR image of unlabeled hMSC and hMSCs with ferumoxytol in FBS, HS, and StemPro® media, seeded in agarose scaffold and implanted in cartilage defects of a pig femur. (d) Representative sagittal MR image of unlabeled hMSC and hMSCs labeled with ferumoxytol in HS, protamine, and protamine + heparin media, seeded in agarose scaffold and implanted in cartilage defects of a pig femur. (e) Corresponding T2 relaxation times of unlabeled, and labeled hMSCs implants.