A stem cell is an unspecialised cell with a remarkable ability to divide over and over and become differentiated into another type of cell, replacing damaged body tissue.
The Current Role of Stem Cells in Orthopaedic Surgery. Maniar HH, Tawari AA, Suk M and Horwitz DS. Malays Orthop J. 2015 Nov; 9(3): 1–7.