Safety and Effects of Intravaginal Administration of Lacticaseibacillus rhamnosus CRL1332 Immobilized on Nanofibers in a Murine Experimental Model

Abstract

The design of probiotic hygiene products for daily use is considered an adequate alternativefor the restoration of the vaginal microbiome, maintaining health, and/or preventing infections ofthe female urogenital tract. Most of these probiotic products are available on the world market, buttheir efficacy and safety are not sufficiently documented. One of the requirements to transfer novelprobiotic formulas/products to the productive sector is to demonstrate their innocuity and the absenceof adverse or collateral effects on the host, mainly assayed in experimental models. The inclusion ofbeneficial lactobacilli in nanofibers by electrospinning technique has shown promising applicationpossibilities, and the immobilization of Lacticaseibacillus rhamnosus CRL1332 in nanofibers withand without bioprotective substances and their characterization were previously performed by ourresearch group. In this work, the safety of the intravaginal (i.va.) administration of these functionalnanofibers in a murine experimental model was evaluated. L. rhamnosus CRL1332 immobilized indifferent nanofibers was intravaginally inoculated into mice (seven daily doses). Vaginal washeswere taken for microbiological (cultivable lactobacilli) and cytological techniques, and the vagina wasused for histological and morphological-ultrastructural evaluation. Our results demonstrated thatthe intravaginal administration of L. rhamnosus CRL1332 immobilized in nanofibers is safe in murinemodels, given the absence of an inflammatory response at the cytological and histological levels, withminor modifications at the ultrastructural level, and also related to the normal cultivable vaginalmicrobiota. On the other hand, the number of cultivable lactobacilli increased in the vagina of micereceiving L. rhamnosus CRL1332 nanofibers. The results indicate the safety of lactobacilli-functionalnanofibers and support their inclusion in the design of vaginal probiotic products to prevent/treaturogenital infections and reconstitute the women’s vaginal microbiota.