Expansion or Incubation? Which is Better to Manipulating Stem Cells for Improving the Effects of Umbilical Cord Blood Transplantation

Abstract

Background: Delayed hematopoietic recovery was one of the factors that limited the clinic application of umbilical cord blood (UCB) transplantation. Two different methods of overcoming the limitation were evaluated by this systematic review and meta-analysis. One strategy was to expand UCB unit ex vivo for increasing cell dose and another strategy was to incubate UCB unit with small molecules in vitro for enhancing bone marrow (BM) homing ability. Methods: Relevant literatures were collected from 2000 to 2020 by searching the databases of PubMed, Medline, and EMBASE. A total of 15 studies that met the inclusion criteria were included in the meta-analysis. Results: Similar clinical effects including neutrophil recovery (P=0.308), platelet recovery (P=0.4754), and 100-day survival (P=0.4216) between two methods were observed. Faster neutrophil recovery was associated with higher infused total nucleated cells (TNCs) (R2=0.4526 P<0.05) and higher infused CD34+ cells (R2=0.9777 P=0.095) in patients of expansion group and incubation group, respectively. Conclusion: Although the treatment outcomes by using expanded stem cells were getting better all these years with fast development of cell culture techniques according to our cumulative meta-analysis. It seems the application of incubation procedure was safer and more convenient than expansion regarding to their similar clinic effects. This study was registered at RROSPERO (Registration no. CRD42020149750).