Disclosed is a method for preparing an implant including a culture of cells on a membrane, the method including steps that consist of: securing the membrane to a mounting; placing the membrane in a recess of a housing providing two spaces having adjusted heights, above and below the membrane; injecting, into the spaces, a liquid capable of transforming into gel at a transport temperature lower than an injection temperature of the liquid; and bringing the housing to the transport temperature, so as to form an implant including the membrane and two layers of gel having adjusted thicknesses, on two opposite faces of the membrane, respectively.