CHEMS is an acidic cholesterol ester. It self-assembles into bilayers in alkaline and neutral aqueous media.
1. The role of helper lipids in lipid nanoparticles (LNPs) designed for oligonucleotide delivery
Xinwei Cheng, Robert J Lee. Adv Drug Deliv Rev. 2016 Apr 1;99(Pt A):129-137. doi: 10.1016/j.addr.2016.01.022.
Lipid nanoparticles (LNPs) have shown promise as delivery vehicles for therapeutic oligonucleotides, including antisense oligos (ONs), siRNA, and microRNA mimics and inhibitors. In addition to a cationic lipid, LNPs are typically composed of helper lipids that contribute to their stability and delivery efficiency. Helper lipids with cone-shape geometry favoring the formation hexagonal II phase, such as dioleoylphosphatidylethanolamine (DOPE), can promote endosomal release of ONs. Meanwhile, cylindrical-shaped lipid phosphatidylcholine can provide greater bilayer stability, which is important for in vivo application of LNPs. Cholesterol is often included as a helper that improves intracellular delivery as well as LNP stability in vivo. Inclusion of a PEGylating lipid can enhance LNP colloidal stability in vitro and circulation time in vivo but may reduce uptake and inhibit endosomal release at the cellular level. This problem can be addressed by choosing reversible PEGylation in which the PEG moiety is gradually released in blood circulation. pH-sensitive anionic helper lipids, such as fatty acids and cholesteryl hemisuccinate (CHEMS), can trigger low-pH-induced changes in LNP surface charge and destabilization that can facilitate endosomal release of ONs. Generally speaking, there is no correlation between LNP activity in vitro and in vivo because of differences in factors limiting the efficiency of delivery. Designing LNPs requires the striking of a proper balance between the need for particle stability, long systemic circulation time, and the need for LNP destabilization inside the target cell to release the oligonucleotide cargo, which requires the proper selection of both the cationic and helper lipids. Customized design and empirical optimization is needed for specific applications.
2. Small interfering RNA for cancer treatment: overcoming hurdles in delivery
Nitin Bharat Charbe, Nikhil D Amnerkar, B Ramesh, Murtaza M Tambuwala, Hamid A Bakshi, Alaa A A Aljabali, Saurabh C Khadse, Rajendran Satheeshkumar, Saurabh Satija, Meenu Metha, Dinesh Kumar Chellappan, Garima Shrivastava 0, Gaurav Gupta, Poonam Negi, Kamal Dua, Flavia C Zacconi. Acta Pharm Sin B. 2020 Nov;10(11):2075-2109. doi: 10.1016/j.apsb.2020.10.005.
In many ways, cancer cells are different from healthy cells. A lot of tactical nano-based drug delivery systems are based on the difference between cancer and healthy cells. Currently, nanotechnology-based delivery systems are the most promising tool to deliver DNA-based products to cancer cells. This review aims to highlight the latest development in the lipids and polymeric nanocarrier for siRNA delivery to the cancer cells. It also provides the necessary information about siRNA development and its mechanism of action. Overall, this review gives us a clear picture of lipid and polymer-based drug delivery systems, which in the future could form the base to translate the basic siRNA biology into siRNA-based cancer therapies.
3. When "Chems" Meet Sex: A Rising Phenomenon Called "ChemSex"
Raffaele Giorgetti, Adriano Tagliabracci, Fabrizio Schifano, Simona Zaami, Enrico Marinelli, Francesco Paolo Busardò. Curr Neuropharmacol. 2017;15(5):762-770. doi: 10.2174/1570159X15666161117151148.
The term "chemsex" was coined to indicate the voluntary intake of psychoactive and non psychoactive drugs in the context of recreational settings to facilitate and/or to enhance sexual intercourses mostly among men who have sex with other men (MSM). The authors aimed to review the mechanisms of action, the toxicity and the pattern of use and abuse of substances involved in "chemsex" practice together with the sociocultural background underlying it and the health-related consequences that they may have. Gamma-hydroxybutyrate, gamma-butyrolactone,1,4-butanediol, mephedrone, methamphetamine, sildenafil, tadalafil, vardenafil and alkyl nitrites have been described in their role of "chemsex drugs" including pharmacological action and in their implication to impair capacities to chose sexual partners and consensual sex. Moreover, it has been demonstrated that sexual activity over protracted length of time under the influence of chemsex drugs can result in rectal trauma or penile abrasions and a significant increase of the risk of transmission of sexual transmitted diseases, especially in case of condomless intercourses, which are frequent in this context, representing therefore a serious health threat. One of the major problems to establish health policy priority interventions for chemsex is the lack of available epidemiological data on the issue. Finally, social actions should be taken in order to break down the barriers that currently exist among chemsex drug users in accessing services, including the shame and stigma often associated with drug use. In conclusion, more specific resources to face high risks of infections and HIV transmission are required in bisexual and homosexual individuals having SUID: sex under the influence of drugs.