Abstract: A method for isolating tissue repair promoting substances from human or animal blood, which method comprises collecting the human or animal blood from a single human or animal individual in a first container of a container system comprising at least first and second interconnected containers; centrifuging the container system containing said blood so as to separate the blood in various fractions including a plasma fraction; transferring at least part of the plasma fraction to said second container of the container system; subjecting the plasma fraction in said second container to a low temperature so as to obtain a precipitate comprising tissue repair promoting substances; concentrating said precipitate in said second container so as to obtain a first fraction comprising a major part of the non-precipitated material, and a second fraction comprising at least the major part of the precipitate and a minor part of the non-precipitated material; and separating said second fraction comprising the tissue repair pro