Abstract
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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