RNA nanoparticle design puts safe and stable therapeutic elements into cells

For years scientists have known that RNA, a relative of DNA, is a potential tool for nanotherapy - nanotherapy, whereby elements of therapy are introduced into the body by nanoparticles. . But there are many difficulties when creating therapeutic RNAs, long-term maintenance or high stability and non-toxicity when introduced into target cells.

With two articles in Molecular Therapy magazine, Biomedical Engineering Doctor Peixuan Guo of the University of Cincinnati ( University of Cincinnati, UC ) described in detail how to create large RNA nanoparticles and check their safety when transporting therapeutic elements into target cells.

Professor Guo said: ' These are two important events of nano RNA therapy. One problem in RNA therapy is that it requires a relatively large amount of RNA. In this study, we focused on the most challenging problem of creating large-scale RNA molecules at an industrial scale using the bipartite approach, which found that pRNA could be condensed. from two smaller RNA sections ".

Guo and a number of researchers at the National Cancer Institute ( National Cancer Institute, NCI ) studying RNA for decades have pioneered the use of a flexible structural unit in nanotechnology, or creating Functional systems at the molecular level. In 1987, he discovered encapsulated RNA (packaging RNA, pRNA) in non-29 bacteriophage that could start a motor (operating complex) to encapsulate DNA into its protein shell. In 1998, his laboratory discovered that pRNAs could self-assemble or be inserted into nanoparticles to start the motor.

In his most recent study, Guo and colleagues set out many detailed studies to design a 117-base-long functional pRNA that carries small interfering RNA molecules (small interfering RNA, siRNA). siRNA is an effective tool to inactivate or ' mute ' genes in cells, previous attempts to produce chemically modified siRNA have remained only 15-45 minutes in the body and often causes unwanted immune responses.

' The pRNA particles that we created associated with siRNA have a half-life of 5 to 10 hours in lab animals, no toxicity and no immune response ,' Gs. Guo said. ' A 10-fold increase in circulating time in the body is important in the development of therapeutic drugs and a way to test the therapeutic ability of RNA nanoparticles .'

The size of a structural pRNA molecule is important for effective transport of therapeutic factors to diseased tissues.'RNA nanoparticles must be between 15 and 50 nanometers in size ,' Guo said. ' It must be large enough to be absorbed by the body and not enter cells randomly and cause toxicity, but must be small enough to enter the target cell with the aid of surface receptors. face of the cell . '

In the article ' The combination of pRNA-siRNA nanoparticles using the binary method ,' Guo and colleagues used two pieces of RNA synthesized to produce 117-base long pRNAs, which can be concentrated. with other pRNAs and perform functions in the motor of bacteriophage 20 to pack DNA.

The dichotomous method in pRNA synthesis has overcome the size limit obstacle when synthesizing RNA nanoparticles, Guo said. ' Nanoparticles are quite effective in conveying and releasing therapeutic elements and making' silences' genes in cells. The ability to synthesize nanoparticles allows for improved RNA to go further to maintain its stability and reach specific goals . "

The second edition, ' Determining the pharmacokinetics of non29 pRNA nanoparticles synthesized by chemical monomers to convey to the system ,' was developed from the study, explaining that improved three-dimensional pRNA particles Successfully produced thanks to the two-piece method. Improved nanoparticles are resistant to common enzymes, can attack and degrade RNA; Maintain cell chemistry and metabolism stability.

Moreover, when transferred to target cells in laboratory animals, these nanoparticles are non-toxic and do not cause an immune response, allowing nanoparticles to perform attachment to in vivo cancer cells. Previous studies have coated therapeutic siRNA into a polymer ' coat ' or liposome to transfer into cells.

'To our knowledge, this is the first time that' bare 'nanoparticles have been tested comprehensively in vivo and proven safe, as well as transporting them to tumor tissue with a Specific targeting mechanism , 'Guo Guo said. ' This suggests that uncoated pRNA nanoparticles have all effective pharmacological properties to make an efficient nano-transport model for many medical applications .'