The invention provides a pharmaceutical composition for repairing, or replacing a damaged tissue, and a pharmaceutical composition for improving myocardial infarction. The pharmaceutical compositions of the present invention comprise: a biologically compatible peptide hydrogel comprising at least one self-assembling peptide nanofiber, wherein the self-assembling peptide nanofibers are complementary to each other and at least one cell selected from the group consisting of autologous stem cells, progenitor cells, committed cells, and mature somatic cells.
