Abstract: The present invention relates to blood serum and dermally-derived cells for use in tissue repair. Particularly it relates to blood serum and collagen producing cells for use in the treatment of connective tissue injuries. Preferably the cells and the blood serum are autologous and the connective tissue to be repaired is a tendon or ligament. Also provided is a method of treating connective tissue injuries by the administration of blood serum and collagen producing cells directly to the site of injury. It also relates to the use of blood serum and muscle-like cells for use in the treatment of muscle injury, particularly skeletal muscle injury.