Increased graft content of vascular progenitor cells is associated with reduced toxicity following autologous hematopoietic transplantation.

Objective: Endothelial-like vascular progenitor cells (VPCs) can be collected in peripheral blood stem cell (PBSC) products that are used in hematopoietic stem cell transplantation (HSCT). The association between VPCs in PBSC products and transplant-related toxicity caused by high-dose chemo/radiotherapy was assessed to identify potential mediators of vascular repair.

Materials And Methods: PBSC grafts in 29 patients (mean age: 48 years; range, 20-67 years) undergoing autologous HSCT were analyzed using a cell culture assay for VPC cluster formation in fibronectin-coated dishes in serum-rich angiogenic conditions. Transplant toxicity was estimated using total length of hospital stay (LOS) following HSCT and the Seattle criteria for transplant-related organ toxicity for 8 organ systems (grade 0-4).

Results: LOS following graft reinfusion was lower (14.7 vs 20.0 days, p = 0.002) and the mean number of organs with any toxicity (1.0 vs 2.4, p = 0.016) or with toxicity grade > or = 2 was reduced (0.2 vs 1.6 organs, p = 0.007) in patients with high graft VPC content (n = 10, >2.0 x 10(3) VPCs/kg) compared with reduced VPC content (n = 19, < or = 2.0 x 10(3) VPCs/kg). An association between graft CD34(+) levels and LOS or organ toxicity was not observed. In addition, graft VPC levels were independent of graft CD34 counts, peripheral blood monocytes and hemoglobin levels, age, and disease (p = NS).

Conclusion: PBSC products enriched for VPCs are associated with reduced toxicity following HSCT. Identifying specific factors that contribute to high graft VPC levels is needed.