Human Skin as an Ex Vivo Model for Mycobacterium leprae Maintenance and Studies of Leprosy

Abstract

The in vitro cultivation of M. leprae has not been possible since it was described as causing leprosy, and the limitation of animal models for clinical aspects makes studies on leprosy and bacteria-human host interaction a challenge. Our aim was to standardize the ex vivo skin model (hOSEC) to maintenance and study of M. leprae as an alternative animal model. Bacillary suspensions were inoculated into human skin explants and sustained in DMEM medium until 60 days. Explants were evaluated by RT-PCR-16SrRNA, and cytokines gene expression. Viability and infectivity of bacilli recovered from explant (D28 and D60) were evaluated using the Shepard’s model. All explants were RT-PCR-16srRNA positive. Viability and infectivity of recovered bacilli from explants, analyzed after 5 months of inoculation in mice showed an average positivity of 31%, being the highest positivity in the D28 groups (80%). Furthermore, our work showed different pattern in cytokines gene expression (TGF-β, IL-10, IL-8 and TNF-α) in the presence of alive or dead bacilli. Although changes can be made for improve future experiments, our results have demonstrated that it is possible to use the hOSEC to maintain M. leprae for 60 days, interacting with the host system, an important step in the development of experimental models for studies on the biology of the bacillus, its interactions, and drug susceptibility.