Thin film devices, e.g., multilayer thin film devices, that encapsulate cells for transplantation into a subject are provided. Also provided are methods of using and methods of preparing the subject devices. The thin film devices include a first porous polymer layer and a second porous polymer layer that define a lumen therebetween and encapsulate a population of cells within the lumen. The thin film devices can promote vascularization into the lumen of the device via the pores in the first polymer layer and/or second polymer layer； limit foreign body response to the device； limit ingress of cells, immunoglobulins, and cytokines into the lumen via the first and the second polymer layers； and release from the first polymer layer and/or the second polymer layer molecules secreted by the population of cells.
