A method for promoting expression of a heat shock protein, or for inhibiting cell injury or cell death, or for treating a disease for which cell or tissue protection is desired, or for promoting production of IL-10, or for inhibiting production of IL-8, by administering an effective amount of a fraction containing a hyaluronic acid tetrasaccharide comprising four saccharide residues and having certain physicochemical properties or by administering an effective amount of an isolated and substantially pure tetrasaccharide of formula (1) described in the application. Methods for preserving an organ.