High levels of donor-derived ECs and hematopoietic cells following primary and secondary transplantation. (A) Liver from recipients of GFP⁺ BM (2-5 × 10⁶ cells), GFP⁺ KSL (500-2000 cells), or from unfractionated bone marrow (WBM) (10⁶ cells) serially transplanted from primary recipients (secondary transplantation) was examined to determine the frequency of portal veins with GFP⁺ ECs. Portal veins were considered positive if 10% or more of the ECs integrated within the vessel wall were GFP⁺, CD31⁺, or VWF⁺. 2nd Tx indicates secondary transplantation. (Error bars indicate SEM; n = 3-6 mice per group [P ≤ .01]). (B) Donor-derived, multilineage hematopoiesis in the peripheral blood of a secondary recipient 3 months after transplantation. The percentage of GFP⁺ donor cells expressing individual hematopoietic lineage markers is indicated.