Biotechnology Drug Liposome
In recent years, the development of biotechnology drugs has been advancing by leaps and bounds. Many biotechnology products have been widely used in clinics, and their application value has attracted more and more attention. A survey conducted in the United States from August 1993 to March 1995 showed that the number of biotech drugs listed as clinical trials increased by 64% in less than two years. Cancer is the disease with the most applications of biotechnology products. Other diseases involved include AIDS, amyotrophic lateral sclerosis, asthma, diabetes, heart disease, Lyme disease, multiple sclerosis, rheumatoid arthritis, stroke, and viral infections , Wound healing, inhibit organ transplant rejection. The types of biotechnology products include cytokines, monoclonal antibodies, vaccines, genes (siRNA, plasmid DNA, antisense nucleic acids), etc.
Growth Factor Liposome
Growth factors are cytokines that stimulate cell growth activity. It can bind to specific, high-affinity cell membrane receptors and participate in the regulation of cell growth and other cellular functions. Growth factors exist in platelets, various adult and embryonic tissues and most cultured cells, and are specific to different types of cells. Epidermal growth factor, fibroblast growth factor, insulin-like growth factor, interleukin-like growth factor, etc. can all play important pharmacological effects in the skeletal system, blood system, endocrine system, immune system, etc. through different mechanisms. However, it is a pity that growth factors cannot pass through many physiological barriers in the body using conventional intravenous injection or oral administration methods.
Nerve growth factor (NGF) is a nutritional factor for central cholinergic neurons, which can significantly improve the loss of cholinergic neurons in the basal forebrain, increase the activity of intracellular choline acetyltransferase, and thereby increase the synthesis and storage of acetylcholine And release, essentially improve memory and recognition dysfunction, so as to achieve the effect of preventing and treating Alzheimer’s disease. Scientists prepared NGF liposomes with surface modified bradykinin receptor agonist analog RMP-7. The tissue distribution experiment in rats shows that only 1/4000 of NGF without liposome encapsulation enters human brain tissue. After long-circulating liposome encapsulation, it increases to about 2.4 times that of NGF, and RMP-7 is connected to The surface of NGF liposome can increase the concentration of NGF in rat brain tissue by more than 10 times. The results of water maze experiment and platform jumping experiment also showed that the rats in the NGF liposome group modified with RMP-7 had greatly improved spatial learning ability and memory ability compared with other groups.
siRNA Liposome
RNA interference (RNAi) based on small interfering RNA (siRNA) means that when a double-stranded RNA (dsRNA) that is homologous to a certain segment of the endogenous mRNA coding region is introduced into the cell, the mRNA is specifically degraded, and cause the silencing of the gene expression. This is a process in which dsRNA molecules shut down or silence the expression of the corresponding sequence gene at the mRNA level, that is, sequence-specific post-transcriptional gene silencing (PTGS). With the deepening of research, how to introduce siRNA into experimental animals or humans through blood vessels has become a bottleneck for the further promotion and application of this technology. SiRNA without any modification is degraded extremely fast in the body and has a short half-life, so it cannot maintain an effective drug concentration. The particle size of siRNA-loaded liposomes is usually about 100 nm, and the biocompatibility is also very good, so it is widely used as a delivery vehicle for siRNA. For example, after simple mixing, neutral DOPC can encapsulate 65% of siRNA, while other lipids such as DOPE, DSPC, PC and other neutral lipids can be used to prepare liposomes. The entrapment efficiency of liposomes prepared by DOPC and siRNA is about 65%. After administration to nude mice with ovarian cancer, in vivo imaging experiments can clearly see that DOPC liposomes are obviously taken up in tumors and livers. The expression of EphA2 protein in the tumor can be significantly reduced within 48 hours after one administration, and the tumor volume is significantly reduced.
Vaccine Drug-Encapsulated Liposome
Liposomes are easily taken up by the mononuclear macrophage system, and the latter is responsible for the processing and presentation of antigens. Therefore, liposomes can be used as immune adjuvants to enhance the humoral and cellular immunity of vaccines. The physical and chemical properties of liposomes, such as charge density, membrane fluidity and antigen density, have certain effects on the immune response. In addition to antigens, other immunomodulators, such as amphiphilic muramyl peptides or soluble lipids (monophosphoryl lipid A, muramyl tripeptide-phosphatidylethanolamine), can also be incorporated into liposome lipid membranes to enhance auxiliary effect. The Swiss Serum Vaccine Institute has developed a new liposomal hepatitis A vaccine and has undergone clinical trials. The vaccine contains formalin-inactivated hepatitis A virus particles and influenza virus hemagglutinin, and is characterized by not only inducing the production of antibodies against liver antigens, but also expressing influenza virus proteins.