The key to successful gene therapy is integration of tissue specificity and fine-tuned target gene expression. iGEM Team Heidelberg 2010 unlocks the world of synthetic microRNAs. We engineered a toolkit for standardized measurements of interactions between artificial miRNAs and their binding sites. Thus, the expression level of any gene of choice could be arbitrarily adjusted by employing the corresponding binding site design. To produce tissue specific miRNA gene shuttles, we developed an evolution-based method for synthesis of new adeno associated viruses. In the future, miBricks could open the doors to new Synthetic Biology based medical approaches.