Current Advances in Red Blood Cell Generation Using Stem Cells from Diverse Sources

Table 2

Current representative RBC-producing strategies using circulating HSPCs.

Culture methods			Total cell fold expansion	RBC maturation characteristics			Estimated transfusion unit	Reference
Strategy	Media	Period		Enucleation rate	Hb amount	HbA/HbF ratio
3-step protocol	EIS (step 1)	18 days		81%	N.A	88 : 12	N.A	[68]
	ES (step 2)
	E (step 3)
3-step protocol	FST (step 1)	21 days		4%	40–50 g of Hb	40 : 60	1-1.5 units	[89]
	EIS (step 2)
	IE (step 3)
4-step protocol with feeder cells	FST+feeder (step 1)	38 days		99.4%	~30 g of Hb	45 : 55	8.8 units	[69]
	EIS (step 2)
	E+feeder (step 3-step 4)
2-step protocol with feeder cells	EIS (step 1)	21 days		64%	19 g of Hb	N.A	0.75 units	[70]
	EIS+feeder (step 2)
2-step protocol with bioreactor	EIS (step 1)	21 days		N.A	30.8 g of Hb		560 units	[80]
	EI (step 2)

E: erythropoietin; F: fms-related tyrosine kinase 3 ligand; GM: granulocyte-macrophage colony-stimulating factor; I: interleukin 3; S: stem cell factor; T: thrombopoietin. Fold expansion of CD34⁺ HSPCs and erythroblasts; hemoglobin amount of 10⁶ CD34⁺ cell-derived RBC; referred to the authors’ evaluation. 1 unit of RBC transfusion is approximately RBCs.