Microneedle Patch for DNA-Based COVID-19 Nanovaccines

In many countries, there are successful vaccination campaigns against COVID-19. However, resource-limited countries have faced challenges in obtaining vaccines, partly because some areas lack temperature-controlled shipping and storage facilities. In addition, the vaccines must be administered by a healthcare worker via an injection into a muscle. Delivering vaccines into the skin could avoid this need and also generate a stronger immune response due to the skin’s abundance of antigen-presenting cells (APCs).

Hui Li, Beijing University of Chinese Medicine, Guangjun Nie, National Center for Nanoscience and Technology, Hai Wang, National Center for Nanoscience and Technology, all Beijing, China, and colleagues have developed a microneedle patch that delivers a COVID-19 DNA vaccine into the skin and can be stored for over 30 days at room temperature. The researchers based their vaccine on DNA, which is more stable than RNA. However, intramuscular DNA vaccines have been limited in their effectiveness because, unlike RNA or protein, the DNA must find its way inside the cell’s nucleus to work. Delivering the vaccine into APC-rich skin instead of muscle could increase the chances that the DNA enters the nucleus of an APC.

DNA sequences encoding either the SARS-CoV-2 spike protein or nucleocapsid protein were absorbed to the surface of nanoparticles made from deoxycholic-acid-conjugated low-molecular-weight polyethylenimines (DA-LPEI). The team encapsulated an adjuvant (Resiquimod) inside the nanoparticles, which helps to stimulate a stronger immune response. They coated a microneedle patch with the vaccine nanoparticles. The patch contains biodegradable, detachable microneedles that can painlessly penetrate the skin’s outer layer and deliver the nanovaccine.

The researchers tested the system in mice and found that the spike-protein-encoding microneedle patch caused strong antibody and T-cell responses, with no obvious side effects. The work could be a basis for developing COVID-19 vaccines that can be stored at room temperature and are easy to handle.

Separable Microneedle Patch to Protect and Deliver DNA Nanovaccines Against COVID-19,
Yue Yin, Wen Su, Jie Zhang, Wenping Huang, Xiaoyang Li, Haixia Ma, Mixiao Tan, Haohao Song, Guoliang Cao, Shengji Yu, Di Yu, Ji Hoon Jeong, Xiao Zhao, Hui Li, Guangjun Nie, Hai Wang,
ACS Nano 2021.
https://doi.org/10.1021/acsnano.1c03252

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