Reduced plasma ascorbic acid levels in recipients of myeloablative conditioning and hematopoietic cell transplantation.

Hematopoietic cell transplantation (HCT) conditioned using myeloablative conditioning (MAC) is complicated by end organ injury due to endothelial dysfunction and graft versus host disease. Mucositis and oxidant injury results in micronutrient deficiency. Ascorbic acid (AA) levels were measured in 15 patients undergoing HCT conditioned with MAC (11 allogeneic and four autologous HCT). Ascorbate levels declined postconditioning to 27.3 µMol/L (±14.1) by day 0 (P = .03 compared with pretransplant baseline), reaching a nadir level of 21.5 (±13.8) on day 14 (P = .003) post-transplant. Patients undergoing allogeneic HCT continued to have low AA levels to day 60 post-transplant. The role of AA in maintaining endothelial function and hematopoietic as well as T-cell recovery is provided, developing the rationale for repletion of vitamin C following HCT.

Reconstituting donor T cells increase their biomass following hematopoietic stem cell transplantation.

In this study, we used a rapid, highly-sensitive, single-cell biomass measurement method, Live Cell Interferometry (LCI), to measure biomass in populations of CD3 + T cells isolated from hematopoietic stem cell transplant (SCT) patients at various times pre- and post-transplant (days 0-100). CD3 + T cell 'mass spectra' were obtained from five autologous and 20 allogenic transplant recipients. We found a pronounced rise in median T cell biomass (+25%; p <0.001) shortly after transplant (day 14), which moderated by day 60. Further, the inter-patient and intra-patient cell masses were most variable at days 14 and 30 post-transplant. T cell biomass trends were similar in both autologous and allogenic transplant recipients. These data suggest that T cell biomass changes are associated with immune reconstitution occurring in the first few weeks post-transplant. To our knowledge, this is the first time single-cell biomass measurements have been studied in human clinical trials. With refinement, these data may prove useful in guiding the withdrawal of immunosuppression following SCT, reducing the likelihood of Graft-Versus-Host Disease or cancer relapse occurring.