Researchers at the RIKEN Center for Biosystems Dynamics Research in Japan have developed a new system for keeping tissue viable for long-term study once transferred from an animal to a culture medium. The new system uses a microfluidic device made of polydimethylsiloxane (PDMS) with a porous membrane that can keep tissue from both drying out and from drowning in fluid. This study was published in the journal Analytical Sciences.
The team tested the device using tissue from the mouse suprachiasmatic nucleus, a complex part of the brain that governs circadian rhythms. By measuring the level of bioluminescence coming from the brain tissue, they were able to see that tissue kept alive by their system stayed active and functional for over 25 days with nice circadian activity. In contrast, neural activity in tissue kept in a conventional culture decreased by 6% after only 10 hours.
This new method will be useful in observing development and testing how tissues respond to drugs. Experiments with tissues are much more complex and provide important information such as cell to cell interaction, unlike seeded cells where such observation is difficult.
Researchers have used autologous immune cells from the mouse to create nanovesicles to be used in the delivery of drugs to tumors. This technique helped them to create a sufficient number of nanovesicles inexpensively to be used as drug delivery system.
This image shows ligands-grafted extracellular vesicles as drug delivery vehicles. Credit: Xin Zou
Cells naturally release nanovesicles to carry chemical messages between cells. To create targeted nanovesicles, ligands (short pieces of protein) need to be attached to the nanovesicle wall so they can recognize tumor cells. This is done by incorporating DNA into cells and collecting extracellular nanovesicles from cell culture supernatant. However, the yield of nanovesicles is poor using above process. Researchers now developed a new approach by chemically grafting lipid tagged ligands to the cell membrane and then passing them through a seave to create large amounts of fillable and targeted nanovesicles. Research findings are published in journal Cancer Research.
“Currently, natural nanovesicles can be harvested from cell culture supernatant (the fluid surrounding cultured cells) and they are fillable,” said Yuan Wan, a postdoctoral fellow in biomedical engineering, Penn State. “However, there are two problems using them for cancer treatment. There aren’t enough nanovesicles produced in short timescales and they do not have targeting effect.”
“Pushing the cells through a filter is the engineered way to produce lots of nanovesicles,” said Zheng. “This approach enables us to create nanovesicles with different ligands targeting different types of tumors in about 30 minutes to meet actual needs,” said Zheng. “With this approach, we also can put different types of ligands on a nanovesicle. We could have one ligand that targets while another ligand says, ‘don’t eat me.'”
Reference: Wan, Yuan, Lixue Wang, Chuandong Zhu, Qin Zheng, Guoxiang Wang, Jinlong Tong, Yuan Fang, Yiqiu Xia, Gong Cheng, Xia He, and Si-Yang Zheng. “Aptamer-Conjugated Extracellular Nanovesicles for Targeted Drug Delivery.” Cancer Research 78, no. 3 (2017): 798-808. doi:10.1158/0008-5472.can-17-2880.
Research funding: Nanjing Science and Technology Development Foundation, Jiangsu Provincial Medical Youth Talent Award, Natural Science Foundation of Jiangsu Province, U.S. National Institutes of Health.
Researchers of the University of Barcelona have developed a more efficient computational method to identify new drugs. The study, published in the scientific journal Nature Chemistry, proposes a new way of facing the discovery of molecules with biological activity. Researchers devised dynamic undocking (DUck), a fast computational method to calculate the work necessary to reach a quasi-bound state at which the ligand has just broken the most important native contact with the receptor. Since it is based on a different principle, this method complements conventional tools and allows going forward in the path of rational drug design. ICREA researcher Xavier Barril, from the Faculty of Pharmacy and Food Sciences and The Institute of Biomedicine of the University of Barcelona (IBUB), has led this project, which has the participation of professor Francesc Xavier Luque and PhD student Sergio Ruiz Carmona, members of the same Faculty.
The improvement on efficiency and effectiveness in the discovery of drugs is a key target in pharmaceutical research. In this process, the target are molecules that can be added to a target protein and modify its behavior according to clinical needs. “All current methods to predict if a molecule will join the wished protein are based on affinity, that is, in the complex’s thermodynamic stability. What we are proving is that molecules have to create complexes that are structurally stable, and that it is possible to distinguish between active and inactive by looking at what specific interactions are hard to break”, says Professor Xavier Barril.
This approach has been applied in software that identifies molecules with more possibilities to join the targeted protein. “The method allows selecting molecules that can be starting points to create new drugs”, says Barril. “Moreover, -he continues- the process is complementary with existing methods and allows multiplying five times the efficiency of the current processes with lower computational prices. We are actually using it successfully in several projects in the field of cancer and infectious diseases, among others”.
This work introduces a new way of thinking regarding the ligand-protein interaction. “We don’t look at the balancing situation, where two molecules make the best possible interactions, but we also think how the complex will break, which the breaking points are and how we can improve the drug to make it more resistant to separation. Now we have to focus on this phenomenon to understand it better and see if by creating more complex models we can still improve our predictions”, says the researcher. The team of the University of Barcelona is already using this method, which is open to all the scientific community.
Citation: “Dynamic undocking and the quasi-bound state as tools for drug discovery”. Sergio Ruiz-Carmona, Peter Schmidtke, F. Javier Luque, Lisa Baker, Natalia Matassova, Ben Davis, Stephen Roughley, James Murray, Rod Hubbard& Xavier Barril. Nature Chemistry 2016. DOI: 10.1038/nchem.2660 Adapted from press release by University of Barcelona.