Identification of characteristic proteins at late-stage erythroid differentiation in vitro.

The production of red blood cells in vitro, which is useful for basic or clinical research, has been improved. Further optimization of culture protocols may facilitate erythroid differentiation from hematopoietic stem cells to red blood cells. However, the details of erythropoiesis, particularly regarding the behaviors of differentiation-related proteins, remain unclear. Here, we performed erythroid differentiation using two independent bone marrow- or cord blood-derived CD34+ cell sources and identified proteins showing reproducible differential expression in all groups. Notably, most of the proteins expressed at the early stage were downregulated during erythroid differentiation. However, seven proteins showed upregulated expression in both bone marrow cells and cord blood cells. These proteins included alpha-synuclein and selenium-binding protein 1, the roles of which have not been clarified in erythropoiesis. There is a possibility that these factors contribute to erythroid differentiation as they maintained a high expression level. These findings provide a foundation for further mechanistic studies on erythropoiesis.

Establishment and characterization of immortalized erythroid progenitor cell lines derived from a common cell source.

Immortalized erythroid progenitor cell lines, which exhibit potential for enucleated red blood cell (RBC) production, are expected to serve as an in vitro source of RBCs. These erythroid progenitor cell lines have previously been established from a variety of sources; however, large numbers of cell lines have not been established, characterized, and compared from a common cell source. In the present study, 37 cell lines were established from human bone marrow cells from a single donor. The time required for the establishment of each cell line varied greatly from 46 to 246 days. Of these lines, five were selected and their characteristics were analyzed. The cell lines established at the earliest time point showed better results in terms of both karyotype and differentiation potential than those established the latest. Moreover, obvious differences were noted even when cell lines were established at the earliest time point from the same source. These results suggest that it is important to select the best cell lines from ones established at the earliest time point for generating cell lines with low genomic abnormality and high differentiation ability. We have successfully generated an adult type of cell line with 50% cells carrying a normal karyotype and with 25% enucleation efficiency. These findings could be valuable in the development of an optimal method for establishing cell lines.