Influence of Excipient Composition on Survival of Vaginal Lactobacilli in Electrospun Nanofibers

The lack of appropriate delivery systems hinders the use of probiotics in the treatment of vaginal infections. Therefore, the development of a new delivery system for the local administration of vaginal probiotics is necessary. In this study, we selected three vaginal lactobacilli, i.e., Lactobacillus crispatus, Lactobacillus gasseri, and Lactobacillus jensenii, and incorporated them into nanofibers using electrospinning. Polyethylene oxide (PEO) was used as a carrier polymer to produce nanofibers. It was supplemented with alginate and sucrose selected from a group of carbohydrates for their growth-promoting effect on lactobacilli. The interaction between excipients and lactobacilli was evaluated thermally and spectroscopically. Bacterial survival in polymer solutions and in nanofibers immediately after electrospinning and after storage varied among species and was dependent on the formulation. Sucrose improved the survival in polymer solutions and preserved the viability of L. crispatus and L. jensenii immediately after electrospinning, and L. gasseriand L. jensenii during storage. Blending PEO with alginate did not improve species viability. However, the three lactobacilli in the nanofibers retained some viability after 56 days, indicating that composite multifunctional nanofibers can maintain the viability of vaginal lactobacilli and can be used as a potential solid delivery system for vaginal administration of probiotics.

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About this article: Stojanov, Spase, Julijana Kristl, Špela Zupančič, and Aleš Berlec. 2022. “Influence of Excipient Composition on Survival of Vaginal Lactobacilli in Electrospun Nanofibers” Pharmaceutics 14, no. 6: 1155. https://doi.org/10.3390/pharmaceutics14061155

Conclusions

The susceptibility of vaginal lactobacilli to environmental factors and the lack of a suitable delivery system limits their therapeutic use as probiotics. In this study, we propose a novel nanofiber-based delivery system for the local administration of probiotics in the vagina. First, we tested the growth characteristics of three vaginal Lactobacillusspecies (L. gasseri, L. crispatus, and L. jensenii) in the presence of different polymers and disaccharides. We concluded that alginate and sucrose enhanced their growth and were therefore included in electrospinning formulations along with PEO as the carrier polymer. Sucrose preserved the viability of Lactobacillus species in the polymer solutions. It also improved the viability of L. crispatus and L. jensenii during electrospinning and of L. gasseriand L. jensenii during storage in nanofibers. The protective effect of sucrose can be attributed to its amorphization and interaction with the bacterial membrane. However, sucrose decreased the survival of L. gasseri immediately after electrospinning and of L. crispatus during storage. Nevertheless, all species survived the electrospinning in all formulations and retained viability for 56 days when encapsulated in nanofibers. Viability after 56 days differed among species, with L. gasseri showing the highest viability, followed by L. jensenii and L. crispatus, whereby the viability was also dependent on the excipients used for the bacterial encapsulation. In the present study, we determined that only an appropriate composition of the carrier system can result in the required viability of individual probiotics and that the composition must be tailored for each individual species. We showed that nanofibers are a suitable delivery system for vaginal probiotics and can be used for the development of a novel medicine for re-establishing the disturbed vaginal microbiota.

excipients formulation