The purpose of this study is to investigate whether infusion of G-CSF mobilized HLA-mismatched peripheral blood stem cells (G-PBSC) combining decitabine and cytarabine chemotherapy can improve outcomes in myelodysplastic syndromes (MDS) patients.

Inclusion Criteria:

• patients 10 to 90 years old with primary or treatment-related MDS or chronic myelomonocytic leukemia;
• International Prognostic Scoring System(IPSS) intermediate-1,intermediate-2,or high risk;
• bone marrow blasts > 11% or <= 10% and poor cytogenetics;
• lack of an HLA-identical donor;
• Eastern Cooperative Oncology Group (ECOG) performance status 0-2;
• adequate cardiac and hepatorenal functions.

Exclusion Criteria:

• have an HLA-identical donor