Deficiency of Gal-1 in knockout MSCs diminishes the tumor promoting effect of MSCs.

<p>Female Balb/C mice were challenged by orthotopic inoculation of 10³ 4T1 cells alone or in combination with 10⁵ wtMSCs or MSC^Gal-1−/− (A) or scMSCs or siMSCs (B). C) Tumor bearing (initiated by injection of 10⁵ 4T1 cells) mice were injected intravenously once with 10⁶ (open circles) or twice with 3×10⁵ (black circles) wtMSCs or MSCGal^-1−/−. Tumor size (A left panel) was monitored daily or on the 40^th (B left panel) or 20^th day (C) after tumor initiation. Tumor mass was determined by measuring the formaldehyde fixed primary tumors isolated from sacrificed mice (A and B, right panels). Control mice were injected with PBS or MSCs without tumor cells. Data represent the mean ± SD. Significance on A left graph was calculated only for data on day 38. Number of animals in the experimental groups: A left panel: n = 5, A right panel: n = 5, B left panel: n = 6, B right panel: n = 5, C n = 5–6. ** p<0.01, *** p<0.001. D) Tumor incidence of mice challenged with 10³ 4T1 cells alone or in the combination with 10⁵ wtMSCs or MSC^Gal-1−/− was evaluated using Kaplan-Meier analysis. Control mice were injected with PBS, wtMSC or MSC^Gal-1−/−. Mice were considered as tumor bearing when the tumor was palpable. Tumor free animals were surveyed up to 110 days. n = 5.