In 1978, the Cryonics Society of America researchers collaborated with Jerry Leaf of Cryovita Laboratories in experiments that would apply the methodology to cryonic suspensions that were then in use as surgical procedures to treat patients with heart disease. Thus a team led by a thoracic surgeon and a perfusionist would use cardio-pulmonary resuscitation equipment and blood-pumps to quickly cool a patient, and replace his blood with a blood substitute containing cryoprotectants. For several years thereafter, Cryovita Laboratories led by Jerry Leaf and Mike Darwin, were responsible for the initial cryonic suspension of patients of the American Cryonics Society, which were then perfused, transported, and kept in cryogenic storage by Trans Time. This method of making use of contract companies as a means of risk management was unique to the American Cryonics Society and has been followed to the present day.