MyoCell SDF-1 has received approval from the FDA to begin human clinical trials and is intended to be an improvement to MyoCell.  The myoblast cells to be injected are gene-modified prior to injection by an adenovirus vector so that they will release extra quantities of stromal derived factor – 1 or SDF-1 protein. Following injury which results in inadequate blood flow to the heart, such as a heart attack, the human body naturally increases the level of SDF-1 protein in the heart. By modifying the myoblasts to express SDF-1 prior to injection, the levels of SDF proteins in the heart can be increased. The presence of additional quantities of SDF-1 protein released by the myoblasts may stimulate the recruitment of the patient's existing stem cells to the cell transplanted area and, thereafter, the recruited stem cells will assist in the tissue repair and blood vessel formation process.  In preclinical studies, MyoCell SDF-1 provided a 54 percent improvement of heart function compared to 27 percent for the original MyoCell composition, while the placebo control treated animals declined by 10 percent. The preclinical studies also demonstrated that this product candidate can enhance blood vessel formation in damaged hearts.