1. ¹Divisione Ematologia 2, Ospedale San Martino, Genova, Italy
2. ²The Italian Bone Marrow Donor Registry, Ospedale Galliera, Genova, Italy

Correspondence: Dr D Vicente, Divisione Ematologia 2, Ospedale San Martino, Largo Rosanna Benzi 10, Genova 16132, Italy. E-mail: danycvi@ig.com.br

Received 9 March 2006; Revised 28 April 2006; Accepted 2 May 2006; Published online 5 June 2006.

Abstract

A bone marrow harvest is filtered either in the operating room, in the laboratory or during infusion to the patient. Filters are usually discarded. Little is known of haemopoietic progenitor cells (HPCs) trapped in the filters. The aim of the study was to evaluate HPC content in the filters and to assess the outcome of transplants with filter-discarded or filter-recovered cells. Haemopoietic progenitors were grown from filters of 19 marrow transplants. We then compared the outcome of 39 filter-recovered transplants from HLA-identical siblings (years 2001–2004) with a matched cohort of 43 filter-discarded marrow grafts (years 1997–2000). Filters contained on average 21% long-term culture-initiating cells (LTC-IC) and 15% fibroblasts colony-forming units (CFU-F) of the total progenitor cell content. Filter-discarded transplants had significantly more grade II–IV graft-versus-host disease (GvHD) (42 vs 15%, P=0.008) as compared to filter-recovered transplants, and more transplant-related mortality (TRM) (20 vs 3%, P=0.04). The actuarial survival at 5 years is 69 vs 87%, respectively (P=0.15). This study suggests that a significant proportion of LTC-IC is lost in the filters together with CFU-F. Recovery and add back of progenitors trapped in the filters may reduce GvHD and TRM.