Analysis of parameters affecting engraftment in children undergoing allogeneic BM transplants

Animal studies performed on mice have shown that the number of cells infused following ablative regimens affected the speed and quality of engraftment. Similar studies on humans have resulted in contradicting results. We present our experience assessing multiple parameters.

Fifty-eight pediatric patients underwent allogeneic BM transplants at a single institution and were included in a study evaluating the correlation between five engraftment parameters and the time to either neutrophil, or platelet recovery. The parameters included: the number of total nucleated cells per kg (TNC/kg), the absolute CD34(+) cell content per kg (CD34(+)/kg), the number of mononucleated cells per kilogram (MNC/kg), the number of NFU-E/kg and the number of colony-forming units-granulocyte-macrophage (CFU-GM)/kg. Data were analyzed using both multivariate and univariate correlation method and a Student's t-test.

Three satistically-significant logarithmic relationships were found. The first relationship was between TNC/kg and time to ANC reconstitution (p=0.01). The second and third relationship correlated the CD34(+) cell dose with both ANC and platelet recovery.

Based on the statistical data, we conclude that there is no correlation between MNC dose, CFU-GM/kg and BFU-E/kg content, with either neutrophil or platelet recovery. However, TNC and CD34(+) cell dose per kilogram are the most important parameters predicting the length of time between graft infusion and neutrophil recovery, while CD34(+)/kg is the most important parameter predicting the length of time until platelet recovery. We recommend the use of CD34(+) cell dose as the most reliable parameter to determine the size of the graft in pediatric hematopoietic stem cell recipients.