To investigate the optimal ratio of polycationic liposome mediated pCKM-mPTH recombinant gene transfer to skeleton cells in the gene therapy of hypoparathyroidism (HPT).The protective roles of polycationic liposome to DNA were observed by the DNaseIsensitive test. Liposome-plasmid complex (lipoplexes) with various liposome to plasmid ratio and the naked plasmid were transferred both in vivo and in vitro. The supernatants and serums were collected for measuring parathyroid hormone (PTH) with radioimmunoassay.When the ratio of lipoplexes reached 2:1, there were obviously protective roles to DNA. While it was 3:1, mPTH transgene expressing reached peak which the PTH amount was (16.4 +/- 4.8) pg/10,000 cells/24 h. Furthermore, the amount serum PTH of the HPT model SD rats reached the highest (35.9 pg/ml +/- 2.2 pg/ml) till the concentration of pCKM-mPTH is 20 microg/100 microl with 3:1 ratio of lipoplexes.Polycationic liposomes are more effective than naked plasmids for pCKM-mPTH recombinant gene transfer to skeleton cells. The results also indicated that the effect of pCKM-mPTH transferring into muscles might be depended on the optimal ratio and dosage of lipoplexes.
