MSC stimulate “in vivo” the recruitment of macrophages and direct their differentiation into a regulatory-like profile.

<p>A Glass cylinder of 2 cm long, 8 mm wide and around 200 µl internal volume was implanted s.c. into 8-to 12-week-old C57BL/6 mice. Two and 7 days after the cylinders were implanted in the mice, 2×10⁵ MSC in 50 µl of pyrogen free-PBS or PBS alone (controls) were inoculated inside the cylinders, using a 22 g needle. After 15 days the liquid content of the cylinders was aspirated and the levels of the cytokines TNF-α, IL-12p70, IL-12p40 and IL-10 were determined by ELISA (D). Cylinders were removed, washed with saline and placed in cold PBS (4°C) for 30 min. Adherent cells (>90% macrophages) were removed from the interior of each cylinder to obtain a single cell suspension. The number of the macrophages recruited in each cylinder was measured (A), and their expression of Ia^b and CD86 was analyzed by flow cytometry (B-C). Results represent the arithmetic mean ± SEM (n = 12 for each experimental group). *, p<0.05 for Controls (CT) vs MSC.