Abstract: A method of conserving and/or preparing an organ or tissue for transplant for a subject, includes administering to a subject, organ or tissue in need of such treatment an effective amount of a composition including a polypeptide agent including thymosin beta 4 (TB4), an isoform, analogue or derivative of TB4 having biological activity of TB4, an N-terminal variant of TB4 having biological activity of TB4, a C-terminal variant of TB4 having biological activity of TB4, LKKTET or a conservative variant thereof, LKKTNT or a conservative variant thereof, KLKKTET or a conservative variant thereof, LKKTETQ or a conservative variant thereof, TB4 sulfoxide, TB4ala, TB9, TB10, TB11, TB12, TB13, TB14, TB15, gelsolin, vitamin D binding protein (DBP), profilin, cofilin, adsevertin, propomyosin, fincilin, depactin, Dnasel, vilin, fragmin, severin, capping protein, ?-actinin or acumentin, or a stimulating agent that stimulates production of a polypeptide agent as described above, or a conservative variant thereof, in the or