A 3-D hydrogel based system for hematopoietic differentiation and its use in modeling down syndrome associated transient myeloproliferative disorder.

Induced pluripotent stem cells (iPSCs) provide an extraordinary tool for disease modeling owing to their potential to differentiate into the desired cell type. The differentiation of iPSCs is typically performed on 2-dimensional monolayers of stromal cell or animal tissue derived extracellular matrices. Recent advancements in disease modeling have utilized iPSCs in 3-dimensional (3D) cultures to study diseases such as muscular dystrophy, cardiomyopathy, and pulmonary fibrosis. However, these approaches are yet to be explored in modeling the hematological malignancies. Transient myeloproliferative disorder (TMD) is a preleukemic stage, which is induced in 10-20% of children with trisomy 21 possessing the pathognomonic mutation in the transcription factor GATA1. In this study, we established a synthetic 3D iPSC culture system for modeling TMD via hematopoietic differentiation of customized iPSCs. A chemically cross-linkable PEG hydrogel decorated with integrin binding peptide was found to be permissive of hematopoietic differentiation of iPSCs. It provided a cost-effective system for the generation of hematopoietic stem and progenitor cells (HSPCs) with higher yield of early HSPCs compared to traditional 2D culture on Matrigel coated dishes. Characterization of the HSPCs produced from the iPSC lines cultured in 3D showed that the erythroid population was reduced whereas the megakaryoid and myeloid populations were significantly increased in GATA1 mutant trisomic line compared to disomic or trisomic lines with wild-type GATA1, consistent with TMD characteristics. In conclusion, we have identified a cost-effective tunable 3D hydrogel system to model TMD.