Living Microneedles for Intradermal Delivery of Beneficial Bacteria

High Resolution Image Download MS PowerPoint Slide The skin, our first line of defense against external threats, combines a physical barrier and a rich microbial community. Disruptions of this community, for example, due to infectious injury, have been linked to a decrease in bacteria diversity and to mild to severe pathological conditions. Although some progress has been made in the field, possibilities/procedures for restoring the skin microbiome are still far from ideal. The objective of this study was to design and evaluate a dissolvable poly(vinyl alcohol)/polyvinylpyrrolidone microneedle (MN) patch containing live Bacillus subtilis . According to the plan, bacteria were distributed equally throughout the patch without compromising the morphology and mechanical properties of the needles. B. subtilis was successfully released from the MNs, reaching a logarithmic growth phase after 5 h. These MNs demonstrated remarkable antibacterial activity against the Gram-positive pathogenic S. pyogenes, S. aureus, and C. acnes, while the empty control MNs showed no such activity. Finally, mice were inserted with a single MN patch loaded with GFP- B. subtilis presented significantly higher total radiance efficiency (TRE) values compared to the empty-MN mice throughout the entire experiment. This concept of incorporating live, secreting bacteria within a supportive MN patch shows great promise as a bacterial delivery system, offering a potential shift from conventional pharmacological approaches to more sustainable and symbiotic therapies.