Skin microbiome friendly topical formulations containing probiotic – loaded alginate microspheres: in vitro studies

Skin dysbiosis—a perturbed microbiome balance—is associated with numerous skin conditions. To manage dysbiosis, pre- and probiotics may be used as modulators to restore microbial balance. In this study, Lactobacillus casei ATCC 393-based novel probiotic formulation has been elaborated. The antimicrobial activity of L. casei against Staphylococcus epidermidis and Staphylococcus aureus was studied using kill test and well diffusion assay. The probiotic strain was found to be active against S. aureus (0.81 and 0.99 log reduction of S. aureus cells after 5 and 24 h, respectively). The well diffusion assay showed that L. casei metabolites were active against S. aureus (zone of inhibition: 5 mm). Alginate-prebiotic (tapioca flour)-encapsulated probiotic strain microspheres were used as active ingredients in a topical formulation. The safety and efficacy of this formulation was determined in vitro in human keratinocytes (HaCaT) and fibroblasts (HSF), analyzing cytotoxicity, cell proliferation rate, and proinflammatory cytokine (IL-6 and IL-8) release. In addition, the formulation+n exhibited regenerative potential in the scratch test. In vitro studies showed that the formulation containing MP reduced the survival of pathogenic strains (E. coli, S. aureus, C. albicans, C. neoformans) compared to the base formulation, devoid of lactic acid bacteria (even by 2.82 log).