The present invention relates to a method of preparing a composition for wound healing, and for repairing and regenerating human and animal tissue, said method comprising the following steps: a. providing a plasmid DNA in substantially pure form, which encodes a gene that has a positive effect on the progression of the regeneration of the tissue, b. providing a component/components of a self-hardening bio-polymer, and c. providing a cell suspension with cells which promote regeneration, characterized in that components (a), (b) and (c) are incubated with each other simultaneously or successively so that the plasmid and the cell suspension are obtained homogenously distributed in one of the biopolymer components. Furthermore, transfection systems containing a plasmid DNA, a component of a self-hardening biopolymer and a cell suspension with cells promoting regeneration are disclosed. This transfection system does not contain any further transfection-promoting or transfection-mediating substances. Moreover, therapeutical kits, pharmaceutical compositions and their use for the treatment of tissue defects, in particular burn wounds, and for wound healing in the skin are described. In particular, the present invention relates to a transfection system containing a plasmid DNA, a component of the fibrin adhesive and a cell suspension.
