In this study, subjects will receive a single 60 mcg/kg dose of palifermin either as monotherapy or in conjunction with a continuous heparin infusion. The 60 mcg/kg dose of palifermin explored in this study is identical to the current recommended daily dosage for patients with hematologic malignancies who were undergoing autologous PBPC transplantation after receiving total body irradiation and high-dose chemotherapy: 3 consecutive days administered in two cycles with a 5-day non-dosing interval.