ENGRAFTMENT KINETICS AND LONG-TERM STABILITY OF HEMATOPOIESIS FOLLOWING AUTOGRAFTING OF PERIPHERAL-BLOOD STEM-CELLS

Background. We analyzed short-term and sustained hematopoietic reconstitution after high-dose therapy with peripheral blood stem cell (PBSC) support in patients with various malignant disorders. Methods. Fifty-six patients, all with malignant hematologic disorders, were autografted between 1989 and 1994 using PBSC (47 pts) or PBSC + bone marrow (BM) cells (9 pts). PBSC were collected after mobilization with chemotherapy+/-hematopoietic growth factors (GF). Results. All patients engrafted > 0.5 x 10(9)/L polymorphonuclear cells (PMN) and > 50.0 x 10(9)/L Plt at a median of 12 (8-32) and 13 (9-365) days, respectively. Thirty-nine patients were evaluable for long-term graft performance, and their hematologic values at 30 and 100 days, at 6 months and at 1, 2, 3, 4 and 5 years were retrospectively analyzed. Steady counts were recorded over the years. None of the patients had late graft failure. Conclusions. PBSC given after high-dose chemotherapy ensure a fast hematologic recovery with stable graft performance up to five years after autograft. Though this is not definitive proof of the presence of uncommitted stem cells in the PBSC population, it gives further support to the idea that PBSC are as safe as bone marrow for long-term engraftment. A delayed or incomplete recovery of platelets may occur with low PBSC counts or when disease relapse occurs rapidly after autograft.