Engineering Hematopoietic Stem Cells: Lessons from Development

Abstract

Summary Cell engineering has brought us tantalizingly close to the goal of deriving patient-specific hematopoietic stem cells (HSCs). While directed differentiation and transcription factor-mediated conversion strategies have generated progenitor cells with multilineage potential, to date, therapy-grade engineered HSCs remain elusive due to insufficient long-term self-renewal and inadequate differentiated progeny functionality. A cross-species approach involving zebrafish and mammalian systems offers complementary methodologies to improve understanding of native HSCs. Here, we discuss the role of conserved developmental timing processes in vertebrate hematopoiesis, highlighting how identification and manipulation of stage-specific factors that specify HSC developmental state must be harnessed to engineer HSCs for therapy.

Mutations in signal recognition particle SRP54 cause syndromic neutropenia with Shwachman-Diamond–like features

“…Zebrafish model. The zebrafish is an established model for studying hematopoiesis and development (25,26). At 26 hours post fertilization (hpf), expression data indicated ubiquitous staining for the zebrafish homolog srp54 (bottom image, Supplemental Figure 7A).…”

Umbilical Cord Blood Hematopoietic Stem and Progenitor Cell Expansion for Therapeutic Use

“…With an improving knowledge of stem cell niches and microenvironments [118,119] and technological advances, numerous factors have been identiied that regulate HSPC proliferation and diferentiation and some may potentially also control HSC self-renewal. Here, we will restrict our discussion to UCB expansion ex vivo and, as appropriate, discuss clinical applications, while other approaches to generate and assay (in xenograft in vivo models, e.g., in zebraish) patient-speciic HSPCs derived from ES or iPS cells have recently been reviewed and will not be discussed further [118].…”

“…Here, we will restrict our discussion to UCB expansion ex vivo and, as appropriate, discuss clinical applications, while other approaches to generate and assay (in xenograft in vivo models, e.g., in zebraish) patient-speciic HSPCs derived from ES or iPS cells have recently been reviewed and will not be discussed further [118].…”

Endothelial protein C receptor (EPCR) expression marks human fetal liver hematopoietic stem cells

“…Each stage is characterized by distinct transcriptional programs and expression of unique surface markers in addition to a subset of generic HSC markers (2). The early stages of HSC development provide important insights about the molecular programs that govern HSC origin and expansion (2,3). Most studies of HSC ontogeny are established in mouse models and the lack of common HSC markers between mice and human makes it difficult to isolate human HSCs with optimal purity (4).…”

“…However, earlier studies in human cells suggest that EPCR is not associated with HSC activity in adult human BM (11). Recently, it was shown that UM171, a 3 Pyrimidoindole compound known to expand human long-term HSCs, upregulated EPCR expression in human UCB HSCs and that the EPCR positive fraction contained the engraftable HSCs (12,13). Gene expression profiling studies have further shown that EPCR is preferentially expressed in HSCs compared to multipotent progenitors (MPP) from both human UCB and FL (7,14).…”