- Availability of a single cord blood (CB) with at least 3 x 10^7 nucleated cells (NCs)/kg (if HLA identical or 1 HLA-mismatch) or at least 4 x 10^7 NCs/kg (if a 2 HLA-mismatch) at freezing. Use of two CB units ("double cord transplant") will be allowed provided that: 1) a single CB unit fulfilling the above criteria is not available; 2) a maximum of 2 HLA mismatch is present for each CB unit; and 3) a minimum of 4 x 10^7 NCs/kg (as the sum for both CB units) is present at freezing.