**Author details**

improvement in arthritis in the SSEA-3 positive cells group. On Day 5, CTG-labeled cells were detected in the synovial tissue (**Figure 5c** and **d**) and were still present on Day 28 (**Figure 5e** and **f**) in the group transplanted with SSEA-3 positive cells. **Figure 5e** shows representative joint in the group transplanted with SSEA-3 positive cells on Day 28 and **Figure 5f** shows SSEA-3 positive cells in synovial tissue in the immunohistochemical staining of **Figure 5e**. **Figure 5g** and **h** show the progression of joint destruction in the group transplanted with SSEA-3 negative cells on Day 28. CTG-labeled cells were not detected in other healthy organs on Day 28 by fluorescent microscopy (data not shown). These results indicate that SSEA-3 positive cells have the inhibitory effect on arthritis and systemic administration of them is safety.

**Figure 5.** (a) Arthritis score of CAIA mice after mAb injection. SSEA-3 (−) cells group consisted of mice transplanted with SSEA-3 negative cells. SSEA-3 (+) cells group consisted of mice transplanted with SSEA-3 positive cells. Both groups contained three mice. Each score shows average values of three mice and \* means p < 0.05. The X-axis means the day from day 0 when the monoclonal antibody cocktail was administered. (b) Cell tracker green (CTG)-labeled SSEA-3 positive cells (10X). (c, d and e, f) histology of joint of CAIA mouse after CTG-labeled SSEA-3 positive cells injections on day 5 and 28, respectively. Arrows shows CTG-labeled cells and positive cells for SSEA-3 in immunohistochemical staining. Bar = 100 **mm.** (g and h) representative histology of joint of CAIA mouse after CTG-labeled SSEA-3 negative

In our study, SSEA-3 positive cells were detected in RA synovial tissue even under pathological conditions such as RA. Although the synovial tissue we used was collected from various RA disease stages and surgical sites, SSEA-3 positive cells were detected with values of approximately 0.5–1% in all cultured SFMSCs. Collected SSEA-3 positive cells had higher gene expression level and differentiation ability in vitro compared with SSEA-3 negative cells

**4. Conclusions**

cells injections on day 28. Bar = 100 **mm**.

114 Newest Updates in Rheumatology

Rie Kurose<sup>1</sup> \* and Takashi Sawai2

\*Address all correspondence to: riekuro@hirosaki-u.ac.jp

1 Department of Orthopaedic Surgery, Hirosaki University Graduate School of Medicine, Hirosaki, Japan

2 Department of Histopathology, Tohoku University, Sendai, Japan
