Formulation comprising, or derived from, an initial blood composition, wherein the formulation is rich in platelets and/or growth factors and proteins originating from the initial blood composition, and wherein the proteins are in a gelled state. The invention also refers to method for preparing the formulation, comprising the steps of heating and then cooling the initial blood composition at certain temperatures and times. Among other advantages, the formulation in accordance with the invention is biocompatible and biodegradable, presents the desirable biological or medical properties provided by the presence of platelets or growth factors, and also presents high dimensional stability over time.