Japan’s Innovation in 100% Pure mRNA Production: The Next Phase of Vaccines?

A new method of producing entirely pure capped mRNA vaccines has been revealed by Japanese researchers, ushering in the possibility for more effective immunizations with reduced inflammation risk. Image Credit: Mizuki Tada

A scientific team in Japan has introduced a method, known as ‘Purecap’, to enable the production of highly refined mRNA vaccines.

The Japanese research group has formulated a technique that manufactures highly active mRNA vaccines at extreme purity by using a unique cap to effortlessly separate the capped mRNA that is desired. This ‘Purecap’ method extracted Cap2-type mRNA up to complete purity, leading to 3-4 times enhanced production of protein that triggers the immune response. These findings pave the way for purer vaccines, lessening the risk of inflammation due to contaminants. The results of this research have been recently published in Nature Communications.

Possibilities with mRNA Vaccines

mRNA vaccines have previously demonstrated success in therapy against coronavirus variants, sparking interest in potential future use against cancer. Nevertheless, achieving this goal is hindered by vaccine impurity as contaminants can provoke the immune system, leading to inflammation at the injection site, a typical vaccination side effect.

Understanding the Impurities in Vaccines

During the capping stage, impurities in mRNA vaccines are often inserted. In this phase, a cap structure is added that not only aids in mRNA translation but also provides protection and stabilization. Ideally, a vaccine should be comprised of 100% pure single-stranded mRNA, but unwanted double-stranded mRNA might be present, thus decreasing purity.

By employing reversed-phase high-performance liquid chromatography (RP-HPLC), which separates mRNAs based on their attraction or repulsion to water, single- and double-stranded mRNAs with diverse properties can be segregated.

Research Techniques and Discoveries

Under the leadership of Professor Hiroshi Abe, Project Assistant Professor Masahito Inagaki, and Project Associate Professor Naoko Abe from Nagoya University’s Graduate School of Science, in cooperation with Tokyo Medical and Dental University, a special PureCap method was used to attach a hydrophobic tag at the capping phase. This tagged mRNA was easily isolated during the RP-HPLC phase, and a light treatment removed the tag, resulting in a vaccine that was 98% to 100% pure.

As noted by Hiroshi Abe, the excitement over the result was palpable, especially when the RP-HPLC process fully separated the capped and uncapped RNAs. He added that they used the PureCap method to produce over 98% pure capped mRNA for a 4247-base-long coronavirus mRNA.

The researchers carefully studied cap structures known as Cap0, Cap1, and Cap2, present in animal and plant cells. While Cap2 is common in these cells, evaluating its function was previously challenging without access to pure capped mRNA. By employing the PureCap method, they were able to produce highly purified structures of Cap0, Cap1, and Cap2 types, showcasing their prospective use in pharmaceuticals.

Cap2 Structure Advantages

Utilizing Purecap, the group generated Cap2 mRNA and studied its ability to synthesize protein. They discovered that Cap2 mRNA produced 3-5 times more protein than Cap1 mRNA, thus amplifying the immune response. Their Cap2-type mRNAs also triggered a lessened inflammatory reaction compared to mRNAs created with traditional methods.

Abe remarked on the limitations of conventional methods in preparing high-purity capped mRNA, citing concerns over reduced protein synthesis and reactions caused by impurities.

He emphasized that the PureCap technique addresses these issues by selectively purifying only the capped mRNA. Furthermore, the Cap2-type structure produced through this method is more efficient in synthesizing protein and less likely to irritate the immune system. This novel technique holds the promise of enhancing mRNA vaccine safety and efficacy, representing a groundbreaking advancement in the practical application of mRNA medicine and contributing to the underlying principles of mRNA science.

Reference: “Cap analogs with a hydrophobic photocleavable tag enable facile purification of fully capped mRNA with various cap structures” by Masahito Inagaki, Naoko Abe, Zhenmin Li, Yuko Nakashima, Susit Acharyya, Kazuya Ogawa, Daisuke Kawaguchi, Haruka Hiraoka, Ayaka Banno, Zheyu Meng, Mizuki Tada, Tatsuma Ishida, Pingxue Lyu, Kengo Kokubo, Hirotaka Murase, Fumitaka Hashiya, Yasuaki Kimura, Satoshi Uchida and Hiroshi Abe, 11 May 2023, Nature Communications.
DOI: 10.1038/s41467-023-38244-8

Frequently Asked Questions (FAQs) about Purecap

More about Purecap

• Nature Communications: Cap analogs with a hydrophobic photocleavable tag enable facile purification of fully capped mRNA
• Nagoya University Graduate School of Science
• Tokyo Medical and Dental University