A team of researchers from City University of Hong Kong (CityU) have devised an ingenious new alternative to polymer microneedle patches – this one uses ice. Just like existing patches, the ice microneedle patches, or cryomicroneedle patches, can be loaded with drugs, vaccines, cells or other therapeutic molecules and are similarly painless to use.

The team says that using ice has a few advantages over current systems. The most obvious is that it’s a simpler material to make than biodegradable polymers, but they also leave less waste. The ice can also preserve the cells for long-term cold storage.

The principle for these cryomicroneedles is mostly the same: therapeutic cells are loaded into the microneedles, paired with a cryoprotectant then frozen in the ice. These microneedle patches are designed to be applied to the skin like a Band-Aid; once the needles enter the skin, they break off the backing patch and the patient’s body heat melts them, delivering their payload.

In tests, the team used the cryomicroneedles to treat cancer in mice. They loaded the patches with ovalbumin-pulsed dendritic cells – a form of cancer immunotherapy – and found that the immune responses it triggered were better than those from subcutaneous or intravenous injection.

However, the team has noted that shipping and storage of the cryomicroneedles may be difficult due to their requirement to remain frozen. Further tests with other payloads are in the works as well.

“The application of our device is not limited to the delivery of cells,” says Dr. Xu Chenjie, associate professor in the Department of Biomedical Engineering at CityU. “This device can also package, store, and deliver other types of bioactive therapeutic agents, such as proteins, peptides, mRNA, DNA, and vaccines. I hope this device offers an easy-to-use and effective alternative method for the delivery of therapeutics in clinics.”

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