The present invention relates to a membrane comprising at least one positively charged, synthetic, hydrophobic polymer, at least one hydrophilic polymer and at least one plasticizer; wherein said membrane is flexible and is capable of supporting at least one of cell adherence, cell proliferation or cell differentiation. The invention further relates to use of a membrane of the invention in the preparation of an implantable devices including cell delivery systems, cell growing surfaces and scaffolds. The invention further provides methods for promoting tissue regeneration in a defected tissue region applying membranes of the invention.