Target cell specific delivery system of anti-cancer drugs by Bio-nano particles.

(1)To表明由乙型肝炎病毒（B virus）的包膜蛋白组成的中空纳米颗粒（Bio-nano particle）是药物向人肝脏的有效递送载体，将模型荧光化合物（钙黄绿素）包封在Bio-nanoparticle中并添加到各种细胞系的培养物中。培养1天后，在人肝癌细胞（HepG 2）中特异性检测到钙黄绿素，但在其他组织来源的细胞中未检测到钙黄绿素。（2）以钙黄绿素为模型，建立了生物纳米粒载药量的测定体系，并对电穿孔法包封钙黄绿素的最佳条件进行了研究。(3)A构建了具有8个半胱氨酸残基取代的突变生物纳米颗粒（M8颗粒）以提高药物包封的效率，因为这些半胱氨酸残基经常形成错误的和不期望的分子内二硫键，其阻止药物流入颗粒。包封到所得M8颗粒中的钙黄绿素的量是包封到野生型生物纳米颗粒中的钙黄绿素的量的2.5倍。(4)By使用（2）中确定的条件，将抗癌药物紫杉醇包封到（3）中描述的改进形式的生物纳米颗粒（M8颗粒）中，并加入到各种细胞系的培养物中。抗癌药物包封在Bio-nanoparticles中，抑制HepG 2细胞生长的效率是药物本身的5倍。因此，这些结果表明Bio-nanoparticles作为药物药物的人类肝脏特异性递送载体的有用性。

(1)To show that the hollow nanoparticle composed of the envelope protein of hepatitis B virus (Bio-nano particle) is an efficient delivery vector of pharmaceutical drugs to human liver, a model fluorescent compound (calcein) was enclosed in Bio-nanoparticles and added to the cultures of various cell lines. After 1-day culture, calcein was detected specifically in human hepatoma cells (HepG2) but not in cells derived from other tissues.(2)The system for measuring the amount of drugs encapsulated in Bio-nanoparticles was established by using calcein as a model, and used to find the optimum conditions of electroporation for encapsulation of calcein.(3)A mutant bio-nanoparticle with substitutions of 8 cysteine residues (M8 particle) was constructed to increase the efficiency of drug-encapsulation, since these cysteine residues frequently formed false and undesirable intramolecular disulfide bridges that prevent the drug influx into the particles. The amount of calcein encapsulated into the resultant M8 particle was 2.5-fold more than that into wild-type Bio-nanoparticle.(4)By using the conditions determined in (2), an anti-cancer drug of pacritaxel was encapsulated into the improved version of Bio-nanoparticle (M8 particle) described in (3) and added to the cultures of various cell lines. The anti-cancer drug encapsulated in Bio-nanoiparticles inhibited the growth of HepG2 cells 5-times more efficiently than the drug itself.Thus, these results showed the usefulness of Bio-nanoparticle as a delivery vector specific to human liver for pharmaceutical drugs.