Objective　　　 To determine the effect of an Ac-αCD nanosystem encapsulating Bcl-xl antisense oligonucleotide (ASON) on the proliferation and apoptosis in pulmonary arterial smooth muscle cells.　　　 Methods　　　 Bcl-xl ASON that had been hallmarked with the Cy3 in 5′-end was synthesized

and then encapsulated into the nanosystem Ac-αCD. Primarily cultured SD rat pulmonary arterial smooth muscle cells were treated by Ac-αCD-Bcl-xl ASON or Ac-αCD for 48 h

and the cells without nanosystem served as control. Confocal microscopy was employed to observe the taking of the nanosystem by the cells. Expression of Bcl-xl at mRNA and protein levels

grow inhibitory rate and apoptotic rate were detected by RT-PCR and Western blotting

MTT assay and flow cytometry

respectively.　　　 Results　　　 There were a great deal of brilliantly red-fluorescent granules distributed evenly in the cytoplasm in the cells treated by Ac-αCD-Bcl-xl ASON. No such red-fluorescent granule was seen in the other 2 kinds of cells. The expression of Bcl-xl at mRNA and protein levels were significantly lower in the cells treated by Ac-αCD-Bcl-xl ASON (P0.05). Cell growth inhibitory rate was (53.61±3.02)% in Ac-αCD-Bcl-xl ASON

(6.30±1.90)% in Ac-αCD and (1.40±0.62)% in control cells. Cell apoptotic rate was (53.04±2.09)% in Ac-αCD-Bcl-xl ASON

(10.98±2.03)% in Ac-αCD and (2.19±0.11)% in control cells

with the former 2 kinds of cells significantly higher than control (P0.01)

so Ac-αCD-Bcl-xl ASON cells than Ac-αCD cells (P0.01).　　　 Conclusion　　　 Our Ac-αCD nanosystem encapsulating Bcl-xl ASON is effectively taken by rat pulmonary arterial smooth muscle cells

and then inhibits cell growth and induces cell apoptosis.