In some embodiments, a micro-tissue particle comprising a scaffold-free population of aggregated cells is provided. The micro-tissue particle may have a diameter less than approximately 1 mm. In some aspects the diameter is less than approximately 500? m. The population of cells may include at least one terminally differentiated cell type. In one aspect, the population of cells may include cardiomyocytes, endothelial cells, smooth muscle cells, mesenchymal stem cells, or a combination thereof. The micro-tissue particle may be used to treat or regenerate an injured, degenerated or diseased tissue. For example, micro-tissue particles that include cardiomyocytes may be administered to myocardial tissue that has been injured due to a myocardial infarction.
