Sex-dependent attenuation of plaque growth after treatment with bone marrow mononuclear cells.

There are clinically relevant differences in symptomatology, risk stratification, and efficacy of therapies between men and women with coronary artery disease. Sex-based differences in plaque attenuation after administration of bone marrow mononuclear cells (BMNCs) are unknown. Forty-five male and 57 female apolipoprotein-E knockout (apoE(-/-)) mice were fed a high-fat diet. At 14 weeks of age, animals received 4 biweekly intravenous sex-matched (males, n=11; females, n=13) or -mismatched (males, n=12; females, n=14) BMNCs obtained from C57BL6/J mice. The rest of the apoE(-/-) mice were vehicle treated (males, n=13; females, n=20) or were age-matched untreated controls (males, n=9; females, n=10). Aortic plaque burden, progenitor cell profiles in bone marrow (BM) and 22 circulating cytokines/chemokines were examined 1 week following the final injection. Only female BMNCs infused into male apoE(-/-) recipients significantly decreased plaque formation (P<0.001). This reparative response univariately correlated with increased CD34(+) (P=0.02), CD45(+) (P=0.0001), and AC133(+)/CD34(+) (P=0.001) cell percentages in the BM of recipients but not with total serum cholesterol or percentage of BM-CD31(+)/CD45(low) cells. In a multivariate analysis, BM-AC133(+)/CD34(+) and BM-CD45(+) percentage counts correlated with a lower plaque burden (P<0.05). Increased granulocyte colony-stimulating factor levels highly correlated with plaque attenuation (r=-0.86, P=0.0004). In untreated apoE(-/-) mice of either sex, BM-AC133(+)/CD34(+) cells rose initially and then fell as plaque accumulated; however, BM-AC133(+)/CD34(+) percentages were higher in females at all times (P<or=0.01). We have demonstrated an atheroprotective effect of female-derived BMNCs administered to male atherosclerotic apoE(-/-) mice; this reparative response correlated with the upregulation of BM-AC133(+)/CD34(+) and CD45(+) cells and of circulating granulocyte colony-stimulating factor. Atherosclerotic female apoE(-/-) mice did not exhibit atheroprotection after BMNCs of either sex. Our findings may have implications for clinical cell therapy trials for coronary artery disease. Further exploration of sex-based differences in atheroprotection and vascular repair is warranted.