A pharmaceutical composition for use in a method of treating a metabolic disease or condition wherein mitochondrial function in a target tissue or cell is impaired, wherein the pharmaceutical composition is a preparation comprising a subcellular apparatus derived and isolated or purified from a mitochondrial network of a cultured cell, wherein the preparation is made by a method comprising: a) providing a cell culture; (b) dissociating the cells of the cell culture to produce a subcellular composition; (c) separating the subcellular composition into a cellular debris fraction and an enriched fraction, which is enriched for subcellular apparatus derived and isolated or purified from a mitochondrial network of the cells of the cell culture, wherein the cellular debris fraction is a solid or pelleted fraction and the enriched fraction is a fluid fraction; (d) separating the enriched fraction into a fraction containing the subcellular apparatus and a fraction substantially lacking subcellular apparatus derived and isolated or purified from a mitochondrial network of the cells of the cell culture, wherein the fraction containing the subcellular apparatus is a solid or pellet fraction and the fraction lacking the subcellular apparatus is a supernatant; and (e) suspending the fraction containing the subcellular apparatus in a solution, thereby preparing a preparation comprising a subcellular apparatus derived and isolated or purified from a mitochondrial network of a cultured cell, wherein the subcellular apparatus of the preparation have a mean size of between 175-950 nm, and wherein: (i) the dissociating comprises applying to the cells of the cell culture a first shear force followed by a second, higher shear force; and wherein the first shear force is applied by douncing and the second shear force is applied by passing the homogenate through a needle; and (ii) both of the separating steps (c) and (d) comprises differential centrifugation; or wherein both of the separating steps (c) and (d) comprises differential size filtration: and (iii) the subcellular apparatus of the preparation have one or more of the following characteristics: Glutamate/malate state 3/state 2 respiratory control ratio (RCR 3/2) of 1-15; Glutamate/malate state 3/state 4o respiratory control ratio (RCR 3/4o) of 1-30; Succinate/rotenone state 3/state 2 respiratory control ratio (RCR 3/2) of 1-15; and Succinate/rotenone state 3/state 4o respiratory control ratio (RCR 3/4o) of 1-30. a) providing a cell culture; (b) dissociating the cells of the cell culture to produce a subcellular composition; (c) separating the subcellular composition into a cellular debris fraction and an enriched fraction, which is enriched for subcellular apparatus derived and isolated or purified from a mitochondrial network of the cells of the cell culture, wherein the cellular debris fraction is a solid or pelleted fraction and the enriched fraction is a fluid fraction; (d) separating the enriched fraction into a fraction containing the subcellular apparatus and a fraction substantially lacking subcellular apparatus derived and isolated or purified from a mitochondrial network of the cells of the cell culture, wherein the fraction containing the subcellular apparatus is a solid or pellet fraction and the fraction lacking the subcellular apparatus is a supernatant; and (e) suspending the fraction containing the subcellular apparatus in a solution, thereby preparing a preparation comprising a subcellular apparatus derived and isolated or purified from a mitochondrial network of a cultured cell, wherein the subcellular apparatus of the preparation have a mean size of between 175-950 nm, and (i) the dissociating comprises applying to the cells of the cell culture a first shear force followed by a second, higher shear force; and wherein the first shear force is applied by douncing and the second shear force is applied by passing the homogenate through a needle; and (ii) both of the separating steps (c) and (d) comprises differential centrifugation; or wherein both of the separating steps (c) and (d) comprises differential size filtration: and (iii) the subcellular apparatus of the preparation have one or more of the following characteristics: Glutamate/malate state 3/state 2 respiratory control ratio (RCR 3/2) of 1-15; Glutamate/malate state 3/state 4o respiratory control ratio (RCR 3/4o) of 1-30; Succinate/rotenone state 3/state 2 respiratory control ratio (RCR 3/2) of 1-15; and Succinate/rotenone state 3/state 4o respiratory control ratio (RCR 3/4o) of 1-30. Glutamate/malate state 3/state 2 respiratory control ratio (RCR 3/2) of 1-15; Glutamate/malate state 3/state 4o respiratory control ratio (RCR 3/4o) of 1-30; Succinate/rotenone state 3/state 2 respiratory control ratio (RCR 3/2) of 1-15; and Succinate/rotenone state 3/state 4o respiratory control ratio (RCR 3/4o) of 1-30.