Tumor Cell Purging by Ex Vivo Expansion of Hemopoietic Stem Cells from Breast Cancer Patients Combined with Targeting ErbB Receptors

The incidence of tumor cell contamination of peripheral blood stem cells: a meta-analysis to evaluate the impact of mobilization regimens and the influence on outcomes in breast cancer patients

Tumor cell contamination (TCC) of peripheral blood stem cells (PBSCs) is a major risk in the autologous PBSC transplant setting. However, the effect of different mobilization regimens (cytokines only versus cytokines + chemotherapy) on TCC of PBSCs and its impact on treatment outcomes have not been systematically reviewed. In the present meta-analysis, we aimed to investigate this effect in breast cancer patients since multiple studies have been conducted in this setting. We systematically searched MEDLINE and Cochrane Library up to May 2012. Seventeen studies (1,819 patients) were assessed. There was no significant difference in the incidence of TCC of PBSCs between the two mobilization regimens. When the analysis was restricted to granulocyte colony-stimulating factor as a cytokine, this difference was again not significant. We also found that TCC of PBSCs was associated with a higher annual recurrence rate in these patients. This suggests that there may be a significant risk for reinfusion of tumor cell-positive PBSCs, and whether it can increase the risk of disease recurrence needs to be determined. This study also raises important questions regarding the causes of TCC of PBSCs. These issues should be investigated systematically in PBSC transplant patients.

Unraveling graft-versus-host disease and graft-versus-leukemia responses using TCR Vβ spectratype analysis in a murine bone marrow transplantation model

The optimum use of allogeneic blood and marrow transplantation (BMT) as a curative therapy for hematological malignancies lies in the successful separation of mature donor T cells that are host reactive and induce graft-versus-host disease (GVHD) from those that are tumor reactive and mediate graft-versus-leukemia (GVL) effects. To study whether this separation was possible in an MHC-matched murine BMT model (B10.BR→CBA) with a CBA-derived myeloid leukemia line, MMC6, we used TCR Vβ CDR3-size spectratype analysis to first show that the Vβ13 family was highly skewed in the B10.BR anti-MMC6 CD8(+) T cell response but not in the alloresponse against recipient cells alone. Transplantation of CD8(+)Vβ13(+) T cells at the dose equivalent of their constituency in 1 × 10(7) CD8(+) T cells, a dose that had been shown to mediate lethal GVHD in recipient mice, induced a slight GVL response with no concomitant GVHD. Increasing doses of CD8(+)Vβ13(+) T cells led to more significant GVL responses but also increased GVHD symptoms and associated mortality. Subsequent spectratype analysis of GVHD target tissues revealed involvement of gut-infiltrating CD8(+)Vβ13(+) T cells accounting for the observed in vivo effects. When BMT recipients were given MMC6-presensitized CD8(+)Vβ13(+) T cells, they displayed a significant GVL response with minimal GVHD. Spectratype analysis of tumor-presensitized, gut-infiltrating CD8(+)Vβ13(+) T cells showed preferential usage of tumor-reactive CDR3-size lengths, and these cells expressed increased effector memory phenotype (CD44(+)CD62L(-/lo)). Thus, Vβ spectratyping can identify T cells involved in antihost and antitumor reactivity and tumor presensitization can aid in the separation of GVHD and GVL responses.

Human mesenchymal stem cells improve ex vivo expansion of adult human CD34+ peripheral blood progenitor cells and decrease their allostimulatory capacity

OBJECTIVE

Bone marrow mesenchymal stem cells (MSC) participate in the bone marrow microenvironment by providing growth factors and matrix proteins, which play a role in the regulation of hematopoiesis, through cell-to-cell interactions. Recently, MSC have been demonstrated to improve expansion of cord blood heamtopoietic stem cells (HSC).

METHODS

In this report, we evaluated the impact of MSC on ex vivo expansion of adult mobilized peripheral blood stem cells (PBSC). Moreover, the effect of MSC on the expanded PBSC allostimulatory capacity was also investigated, due to the well-known immunomodulatory properties of MSC. In addition, the requirement for cell-cell contact in this MSC coculture system was investigated using a transwell system.

RESULTS

Our results show that MSC greatly improved the expansion rate of adult PBSC cells relative to the absolute number of 1) clonogenic cells, 2) long-term cultured cells, or 3) CD34(+) cells. Whereas high levels of IL-6 on its own was sufficient to significantly improve PBSC expansion, direct contact between MSC and PBSC was required to achieve maximal expansion. Finally, MSC decreased the allostimulatory capacity of expanded PBSC.

CONCLUSION

Our data show that MSC efficiently improve expansion of adult PBSC, together with decreasing their allostimulatory capacity. Therefore, this study should provide a clinically relevant method for optimizing PBSC ex-vivo expansion, in particular when poor grafts are obtained.