Allogeneic stem cell transplantation in acute myeloid leukemia: establishment of indications on the basis of individual risk stratification

Rapid ex vivo expansion of highly enriched human invariant natural killer T cells via single antigenic stimulation for cell therapy to prevent graft-versus-host disease

BACKGROUND AIMS

CD1d-restricted invariant natural killer (iNK) T cells are rare regulatory T cells that may contribute to the immune-regulation in allogeneic stem cell transplantation (ASCT). Here, we sought to develop an effective strategy to expand human iNK T cells for use in cell therapy to prevent graft-versus-host disease (GVHD) in ASCT.

METHODS

Human iNK T cells were first enriched from peripheral blood mononuclear cells (PBMCs) using magnetic-activated cell sorting separation, then co-cultured with dendritic cells in the presence of agonist glycolipids, alpha-galactosylceramide, for 2 weeks.

RESULTS

The single antigenic stimulation reliably expanded iNK T cells to an average of 2.8 × 10⁷ per 5 × 10⁸ PBMCs in an average purity of 98.8% in 2 weeks (N = 24). The expanded iNK T cells contained a significantly higher level of CD4⁺ and central memory phenotype (CD45RA^-CD62L⁺) compared with freshly isolated iNK T cells, and maintained their ability to produce both Th-1 (interferon [IFN]γ and tumor necrosis factor [TNF]α) and Th-2 type cytokines (interleukin [IL]-4, IL-5 and IL-13) upon antigenic stimulation or stimulation with Phorbol 12-myristate 13-acetate/ionomycin. Interestingly, expanded iNK T cells were highly autoreactive and produced a Th-2 polarized cytokine production profile after being co-cultured with dendritic cells alone without exogenous agonist glycolipid antigen. Lastly, expanded iNK T cells suppressed conventional T-cell proliferation and ameliorated xenograft GVHD (hazard ratio, 0.1266; P < 0.0001).

CONCLUSION

We have demonstrated a feasible approach for obtaining ex vivo expanded, highly enriched human iNK T cells for use in adoptive cell therapy to prevent GVHD in ASCT.

The treatment of elderly patients with acute myeloid leukemia

BACKGROUND

In patients over age 60 with acute myeloid leukemia (AML), cure rates are under 10% despite intensive chemotherapy. These patients often have comorbidities, and their treatment must be chosen with care. For those who are not candidates for intensive chemotherapy, one of the available options for palliative treatment should be chosen on the basis of an individual risk-benefit assessment.

METHODS

Selective literature review.

RESULTS

An evaluation of the patient's general condition and comorbidities, a geriatric assessment, and specially designed risk scores are useful aids to the choice of an appropriate treatment. Some elderly patients with AML can benefit from intensive chemotherapy despite their age; for highly selected elderly patients, allogeneic stem-cell transplantation is an increasingly feasible option. Hypomethylating agents or low-dose cytarabine can be suitable for some patients. Further options include experimental treatment as part of a clinical trial, and supportive care alone. In the special case of acute promyelocytic leukemia, more than half of all patients can be cured with combination chemotherapy including all-trans retinoic acid.

CONCLUSION

The prognosis of elderly AML patients remains poor despite recent therapeutic advances. The appropriate treatment for each patient can be chosen on the basis of a risk-benefit assessment. Clinical trials evaluating new treatments are urgently needed.

Stem cells derived from cord blood in transplantation and regenerative medicine

BACKGROUND

Physicians of any specialty may be the first persons to whom prospective parents turn for information about the acquisition and storage of stem cells derived from cord blood. Stem cells can potentially be used to treat many diseases, yet they are not a panacea. This article provides an overview of their current and possible future applications.

METHODS

Original papers were retrieved by a selective search of the literature, and the Internet sites and advertising brochures of private stem cell banks were also examined.

RESULTS

Allogeneic hematopoietic stem cells derived from umbilical cord blood (obtained from healthy donors, rather than from the patient to be treated) have been in routine use worldwide for more than ten years in the treatment of hematopoietic diseases. Experiments in cell culture and in animal models suggest that these cells might be of therapeutic use in regenerative medicine, but also show that this potential can be realized only if the cells are not cryopreserved. There is as yet no routine clinical application of autologous hematopoietic stem cells from cord blood (self-donation of blood), even though cord blood has been stored in private banks for more than ten years.

CONCLUSIONS

Autologous stem cells from cord blood have poor prospects for use in regenerative medicine, because they have to be cryopreserved until use. Physicians should tell prospective parents that they have no reason to feel guilty if they choose not to store cord blood in a private bank.