Background: Literature regarding the association of aging and stem cell numbers is conflicting. No compelling evidence exists that hematopoietic stem cell numbers decline with age. Early progenitor cells represent only a fraction of total CD34 cells. The ratio of CFU-GM/CD34 provides a relative estimate of the proportion of primitive hematopoietic stem cells in the stem cell compartment. The hypothesis is that primitive stem cell numbers decrease with age.

Methods: This study describes the relationship between the CFU-GM/CD34+ ratio (categorized as quartiles) and donor characteristics in 108 normal donors of cytokine mobilized hematopoietic stem cells for allogeneic transplant between 6/1995 and 11/2003. The relationship between the CFU-GM/CD 34+ and cell collection characteristics were also studied. Donor characteristics included: age, gender, race/ethnicity, ABO blood group, weight, height, body surface area (BSA); collection characteristics included: total number of mononuclear cells/kg (MNC), CFU-GM/kg (Colony Forming Unit- Granulocyte Monocyte), CD34+ cells/kg and the ratio of CFU-GM/CD34 collected.

Results: The median age of the donors was 42.5 years with range from 10.9 years to 71.4 years. The median CFU-GM/CD34 ratio was 0.060 with range from 0.009 to 0.248. The multivariate analysis demonstrated that higher MNC numbers were associated with a significantly higher CFU-CM/CD34 ratio (p<0.01). No significant decrease in the CFU-GM/CD34 ratio was found with increasing age indicating no general compromise in the stem cell compartment of donors with aging. A non-significant association of the CFU-GM/CD34 ratio to donor gender (p=0.071) and BSA (p=0.072) was also observed.

CONCLUSION: No significant decline in donor hematopoietic stem cell compartment was seen with aging.

Relationship of CFU-GM/CD34+ Ratio Quartiles to Donor and Collection characteristics

CFU-GM/CD34+ Ratio Quartiles
First (0.009–0.034)Second (0.035–0.059)Third (0.06–0.076)Fourth (0.077–0.248)All (n=108)
Abbreviation: CFU GM: Colony Forming Unit- Granulocyte Macrophage; MNC: Mononuclear cell 
Donor Sex (n)      
Male 19 19 11 18 67 
Female 8 8 16 9 41 
BSA sq m      
Median 2.04 2.02 1.81 1.96 1.99 
Range (1.65–2.57) (1.59–2.35) (1.46–2.38) (1.30–2.45) (1.30–2.57) 
Total MNC Collected      
Median (10E8/kg) 5.86 5.77 6.83 8.49 6.22 
Range (10E8/kg) (3.07–11.24) (2.37–13.10) (2.96–15.77) (3.31–15.48) (2.37–15.77) 
CFU-GM/CD34+ Ratio Quartiles
First (0.009–0.034)Second (0.035–0.059)Third (0.06–0.076)Fourth (0.077–0.248)All (n=108)
Abbreviation: CFU GM: Colony Forming Unit- Granulocyte Macrophage; MNC: Mononuclear cell 
Donor Sex (n)      
Male 19 19 11 18 67 
Female 8 8 16 9 41 
BSA sq m      
Median 2.04 2.02 1.81 1.96 1.99 
Range (1.65–2.57) (1.59–2.35) (1.46–2.38) (1.30–2.45) (1.30–2.57) 
Total MNC Collected      
Median (10E8/kg) 5.86 5.77 6.83 8.49 6.22 
Range (10E8/kg) (3.07–11.24) (2.37–13.10) (2.96–15.77) (3.31–15.48) (2.37–15.77) 
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Topics:
abo blood-group system, aging, allogeneic stem cell transplant, cd34 antigens, cytokine, donors, hematopoietic stem cells, transplantation, body surface area, stem cells

Author notes

Corresponding author

2005, The American Society of Hematology
2004
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