In vitro cytotoxicity and surface topography evaluation of additive manufacturing titanium implant materials

Custom-designed patient-specific implants and reconstruction plates are to date commonly manufactured using two different additive manufacturing (AM) technologies: direct metal laser sintering (DMLS) and electron beam melting (EBM). The purpose of this investigation was to characterize the surface structure and to assess the cytotoxicity of titanium alloys processed using DMLS and EBM technologies as the existing information on these issues is scarce. "Processed" and "polished" DMLS and EBM disks were assessed. Microscopic examination revealed titanium alloy particles and surface flaws on the processed materials. These surface flaws were subsequently removed by polishing. Surface roughness of EBM processed titanium was higher than that of DMLS processed. The cytotoxicity results of the DMLS and EBM discs were compared with a "gold standard" commercially available titanium mandible reconstruction plate. The mean cell viability for all discs was 82.6% (range, 77.4 to 89.7) and 83.3% for the control reconstruction plate. The DMLS and EBM manufactured titanium plates were non-cytotoxic both in "processed" and in "polished" forms.Peer reviewe

Graft-versus-Leukemia Effect of Nonmyeloablative Stem Cell Transplantation

Nonmyeloablative stem cell transplantation (NST) is increasingly used with beneficial effects because it can be applied to older patients with hematological malignancies and those with various complications who are not suitable for conventional myeloablative stem cell transplantation (CST). Various conditioning regimens differ in their myeloablative and immunosuppressive intensity. Regardless of the type of conditioning regimen, graft-versus- host disease (GVHD) in NST occurs almost equally in CST, although a slightly delayed development of acute GVHD is observed in NST. Although graft-versus-hematological malignancy effects (i.e., graft-versus-leukemia effect, graft-versus-lymphoma effect, and graft-versus-myeloma effect) also occur in NST, completely eradicating residual malignant cells through allogeneic immune responses is insufficient in cases with rapidly growing disease or uncontrolled progressive disease. Donor lymphocyte infusion (DLI) is sometimes combined to support engraftment and to augment the graft-versus-hematological malignancy effect, such as the graft-versus-leukemia effect. DLI is especially effective for controlling relapse in the chronic phase of chronic myelogenous leukemia, but not so effective against other diseases. Indeed, NST is a beneficial procedure for expanding the opportunity of allogeneic hematopoietic stem cell transplantation to many patients with hematological malignancies. However, a more sophisticated improvement in separating graft-versus-hematological malignancy effects from GVHD is required in the future

Benefit and timing of second transplantations in multiple myeloma: clinical findings and methodological limitations in a European Group for Blood and Marrow Transplantation registry study

Purpose: To use European Group for Blood and Marrow Transplantation registry data to assess the benefit and optimal timing of a double-autologous transplantation strategy for patients with myeloma. Patients and methods: 7,452 transplantation patients described as being either in a multiple graft program ("planned") or not, were analyzed on an intention-to-treat basis. Subsequent multivariate analyses concentrated on the real occurrence of second transplantation, survival, relapse, and transplant-related mortality. Results: Although the transplantation rate in the planned group failed to reach 60%, the median survival from transplantation is 60 months for the planned, compared with 51 months for the remainder group. While the hazard ratio of the planned group is 0.89 (95% CI, 0.79 to 1.00; P =.05) before approximately 70 months, this "effect" is reversed after 70 months, with the hazard ratio estimated as 3.01 (95% CI, 1.07 to 8.46; P =.04). A time-dependent multivariate Cox analysis shows that, taking patients without a second transplantation as a reference group, those receiving a second transplantation in first remission (ie, before relapse) show an increased probability of transplant-related mortality, especially if the transplantation is performed more than 12 months after the first, and the reduction of the risk of relapse is less than when the transplantation is performed earlier. Performing a second transplantation after relapse does not seem to prolong survival, though a second transplantation before relapse is associated with a higher probability of mortality. Conclusion: To improve survival of tandem autologous transplantation in multiple myeloma, the second transplantation should preferably be performed before relapse and within 6 to 12 months of the first transplantation