The vision of Autonomic Computing and Self-Adaptive Software Systems aims at realizing software that autonomously manage itself in presence of varying environmental conditions. Feedback Control Loops (FCL) provide generic mechanisms for self-adaptation, however, incorporating them into software systems raises many challenges. The first part of this thesis addresses the integration challenge, i.e., forming the architecture connection between the underlying adaptable software and the adaptation engine. We propose a domain-specific modeling language, FCDL, for integrating adaptation mechanisms into software systems through external FCLs. It raises the level of abstraction, making FCLs amenable to automated analysis and implementation code synthesis. The language supports composition, distribution and reflection thereby enabling coordination and composition of multiple distributed FCLs. Its use is facilitated by a modeling environment, ACTRESS, that provides support for modeling, verification and complete code generation. The suitability of our approach is illustrated on three real-world adaptation scenarios. The second part of this thesis focuses on model manipulation as the underlying facility for implementing ACTRESS. We propose an internal Domain-Specific Language (DSL) approach whereby Scala is used to implement a family of DSLs, SIGMA, for model consistency checking and model transformations. The DSLs have similar expressiveness and features to existing approaches, while leveraging Scala versatility, performance and tool support. To conclude this thesis we discuss further work and further research directions for MDE applications to self-adaptive software systems.