I actively develop the use of microlensing produced by stars in lensing galaxies to study the inner regions of distant AGNs. I work on both observational and modeling aspects. I performed detailed studies of the micro-lensed induced spectral deformation of several lensed quasars based on single epoch spectra and based on spectrophotometric monitoring data (Sluse et al. 2007, 2011, 2012b). These works allowed me to derive interesting constraints on the structure of the Broad Line Region for different emission lines (Balmer lines, MgII, FeII) as well as on the structure of the absorbing outflow in a broad absorption line quasar (Hutsemékers et al. 2010).