Monocytic Prostaglandin as a Chemotactic Agent for MSC Homing

Method:  The ability of LPS-activated RAW 246.7 murine leukemic monocytes to make PGE2 was measured by ELISA. A transwell assay of C3H10T½ murine MSCs and monocytes was used to assess migration of MSCs. Migration was assessed by DAPI staining. Monocytes were subjected to varying quantities of PGE2, LPS, and ibuprofen, and MSC migration was analyzed at 4 hours following treatment. Cells were counted in five sample areas for each well and the total sum for each was analyzed using ANOVA.

Result:  RAW cells produced 1 ng/mL PGE2 when activated with 1000 ng/mL LPS for 18 hours. In the transwell experiment, migration of MSCs was increased by LPS treatment alone (x=580).  Untreated RAW cells also promoted MSC migration (x=574). Monocytes treated with LPS (x = 581) or PGE2 (x=601) were not more effective in promoting migration. When LPS-stimulated monocytes were exposed to PGE2 (1 ug/mL), monocytes promoted significantly greater MSC migration (x=948, p<0.05). Further investigation revealed that treatment of monocytes with ibuprofen shows an inverse, dose-dependent relationship between ibuprofen dosage and MSC migration, though not statistically significant.

Conclusion:  RAW monocytes, upon exposure to inflammatory mediators, influenced the migration of C3H10T½ cells. The specific interaction is important because inactivated monocytes, in the presence of PGE2, did not cause statistically significant migration as compared to the control group.