A genetically modified dermal micro-organ expressing at least one recombinant gene product, wherein the at least one recombinant gene product is a therapeutic agent, wherein said dermal micro-organ is an explant of living tissue consisting essentially of various dermal components not including epidermal layers , which retain the microarchitecture and three dimensional structure of the dermal tissue from which they derive, with selected to allow passive diffusion of nutrients and gases suitable to cells of said dermal micro-organ and diffusion of cellular waste out of said cells dimensions for minimize toxicity and concomitant cell death due to insufficient nutrition and accumulation of waste in said dermal micro-organ, wherein a dimension of length is 10-60 mm, wherein at least one cross-sectional dimension is 0,5- 3.5 mm, wherein at least some of said cells express at least u na portion of at least one recombinant gene product and wherein said explant dermal micro-organ can be maintained as in vitro explant for several months and wherein said genetically modified dermal micro-organ is for use in a method of treatment in which the modified dermal micro-organ genetically implanted into or under the skin of a recipient subject and wherein the genetically modified dermal micro-organ produces and secretes said at least one recombinant gene product.Un microórgano dérmico modificado genéticamente que expresa al menos un producto génico recombinante, en que el al menos un producto génico recombinante es un agente terapéutico, en que dicho microórgano dérmico es un explante de tejido vivo que consta esencialmente de varios componentes dérmicos sin incluir capas epidérmicas, que conservan la microarquitectura y la estructura tridimensional del tejido dérmico del que se derivan, con dimensiones seleccionadas para permitir la difusión pasiva de los nutrientes y gases adecuados a las células de dicho microórgano dérmico y la difusión de los residuos celulares fuera de dichas cé
