SCIENTISTS have proven the health benefits of drinking green tea. Although many of these claims are still being verified in clinical studies, results from an experiment at ECNU revealed that an antioxidant in green tea, epigallocatechin gallate (EGCG), has beneficial effects in the cellular processes of animals.
Yiyun Cheng research group of the ECNU School of Life Sciences have found a new use for EGCG whereby it transports therapeutic RNAs into cells. Their results were reported and chosen as the cover story for the October issue of ACS Central Science.
ACS Central Science's report.
Small interfering RNAs (siRNAs) contain great potential because they can dial down the expression of disease-related genes for therapeutic use; however, getting siRNAs into cells where they can do their job has been an ongoing challenge for scientists.. Since they are relatively big and carry a negative charge, siRNAs cannot easily cross over the cell membrane, and they are susceptible to degradation by RNA-chomping enzymes. Thus, to overcome these problems, some researchers have tried coating siRNAs with various polymers that can aid in its transportation.
However, most small polymers can’t shuttle siRNAs into cells, whereas larger polymers can be effective but generally carry toxins that inhibit the process.
That's where Yiyun Cheng and the group of research scientists hypothesized whether they could use EGCG in combination with a small polymer to form nanoparticles that can safely deliver siRNA - binding onto EGCG - over the cell membrane and into cells.
The team made their nanoparticles by first combining EGCG and siRNA, which self-assembled into a core of negatively charged electrons. Then, the researchers coated this core with a shell consisting of a small, positively charged polymer. In effect, the nanoparticles passed through several target genes and cultured cells, showing that the particles could cross the cell membrane.
Next, the researchers tested the nanoparticles derived from the first step, by using a siRNA that targeted a pro-inflammatory enzyme on a lab mouse with intestinal injury. The results from the testing showed that nanoparticles improved symptoms such as weight loss, shortening of the colon and intestinal inflammation.
In addition to the gene-silencing effects of the siRNA, EGCG could also contribute to the antioxidant and anti-inflammatory properties produced by the nanoparticles, the researchers noted.
ACS Official News.
Physics. Org's report.
Science Daily's report.
Over 40 media sources have covered this research, including ScienceDaily, GEN, Physics. Org, Eurekalert, USA Science News, Science Blog, Medicilon, Lab Equipment, Drug Target Review, Bioon, Sina Medicine, etc..
The first author Wanwan Shen in the lab.
The project was funded by The National Science Fund for Distinguished Young Scholars and Shanghai Excellent Academic Leading Role Project. It has been conducted for 2 years and initially began as the first stage of a doctoral thesis project by Wanwan Shen, a doctoral graduate student in Yiyun Cheng research group. “I paid less attention to green tea itself, but rather its material structure in the studying process. Green tea is non-ferment; therefore, the biggest challenge confronting us was how to prevent the oxidation of the effective constituents in green tea. We had to be so careful about that,” said Wanwan Shen.
Edited by Siyuan Zhang Proofread by Joshua Mayfield Reviewed by Wenjun Guo