Association between CD34+ and CD3+ T-cells in allogeneic grafts and acute graft-versus-host disease in children undergoing allogeneic hematopoietic stem cell transplantation: A single-center study

BACKGROUND

Acute graft-versus-host disease (aGVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). We examined the association between the composition of the cell subsets present in allogeneic grafts (allografts) and the occurrence and severity of aGVHD in pediatric patients.

METHODS

We retrospectively analyzed 80 consecutive pediatric patients undergoing allo-HSCT at our center.

RESULTS

Both univariate and multivariate analyses showed that the number of CD34⁺ and CD3⁺ T-cells in allografts were the two highest risk factors associated with II-IV aGVHD. Using receiver operating characteristic analysis, the cutoff levels of the allo-HSCT cell doses were used to divide the recipients into low-dose and high-dose groups. The 100-day cumulative incidence of II-IV aGVHD in the high-dose CD34⁺ and CD3⁺ T-cells group was significantly higher than that of the low-dose group (CD34⁺: 57% vs. 29%, p = 0.009; CD3⁺: 63% vs. 18%, p < 0.001). No other clinical factors or cell subsets correlated with aGVHD incidence.

CONCLUSIONS

Our analysis indicates that the CD34⁺ and CD3⁺ T-cell numbers in the allografts could be the risk factors for the development of severe aGVHD (level II-IV). Further studies should aim to optimize the critical number of CD34⁺ and CD3⁺ T-cells to reduce the risk of severe aGVHD occurrence in pediatric patients.

Differentiation of zebrafish spermatogonial stem cells to functional sperm in culture

Molecular dissection and chemical screening on a complex process such as spermatogenesis could be facilitated by cell culture approaches that allow easy access for experimental manipulation and live imaging of specific molecules; however, technical limitations have thus far prevented the complete reconstruction of spermatogenic events in cell culture. Here, we describe the production of functional sperm from self-renewing spermatogonial stem cells (SSCs) in cell culture conditions, using zebrafish testicular hyperplasia cells that accumulate early stage spermatogonia. By serially transplanting hyperplasias into immunodeficient rag1 mutant zebrafish, we succeeded in long-term maintenance and efficient production of starting material for SSC culture. Through improvements of culture conditions, we achieved efficient propagation of SSCs derived from the hyperplasia. When SSCs that underwent the SSC-propagating step for 1 month were transferred onto Sertoli feeder cells, they differentiated into functional sperm that gave rise to offspring. Oxygen at the concentration of air proved to be detrimental for sperm differentiation from SSCs, but not for propagation of SSCs. These results indicate that the whole spermatogenic process can be represented in cell culture in zebrafish, facilitating analyses of the molecular mechanisms of spermatogenesis in vertebrates.