Background MSC’s are adult stem cells present in many tissues, potently immunosuppressive, shown to specifically migrate to damaged areas. MSC’s have been shown to diminish arthritis in animal models although the mechanism of action remains unclear.
Objectives To look for specific migration to inflamed joints, in vivo expansion and elimination of local and systemic injected MSC’s.
Methods Groups of 6 mice were injected with human proteoglycan according to the PGIA protocol. MSCs with the GFP-Firefly luciferase fusion gene were used. The mice underwent repeated bioluminescence imaging (BLI) after intraperitoneal (i.p.), intraarticular (i.a.), intravenous (i.v.) or intracardial (i.c.; in the left ventricle) injection of MSCs in doses of 5×106 i.p., 2×106 i.a., 1×106 i.v. or 0.3×106 i.c. MSC’s were traced a few times per week after the administration of MSC’s.
Results BLI showed that iv administered MSC’s aggregated and leading to pulmonary embolism in a substantial proportion of these mice. Injection of MSCs in the left ventricle followed the routes of the large branches of the aorta. At no point the cells were seen to migrate to the joints in any of the mice. In none of the mice the MSC’s were visible after 5 weeks. At no point an increase in signal was seen. No difference in elimination rate was seen between allogeneic or syngeneic MSC’s (see figure).
Conclusions At no point MSC’s were seen to migrate to the joints after iv or ic injection and in the ip and ia group the cells stayed at the injection site. At no point an increase in signal was seen in any of the mice. In all mice the MSC’s were no more visible after 5 weeks. No difference in the elimination rate was observed between allogeneic or syngeneic MSC’s.
Disclosure of Interest None Declared