3140 – DELINEATING HEMATOPOIETIC AND CARDIAC MESODERMAL FATES FROM HPSCS

• Published in: Experimental hematology 2024-08, Vol.137, p.104461, Article 104461
• Main Authors: Nguyen, Quynh, Manchev, Vladimir, Kent, Greg, Kwan, Jamie, Cohen, Brenda, Kennedy, Marion, Yang, Donghe, Fernandes, Ian, Gagliardi, Mark, Keller, Gordon
• Format: Article
• Language: English
• ISSN: 0301-472X
• DOI: 10.1016/j.exphem.2024.104461

Hematopoietic and cardiovascular fates are specified at the mesoderm induction stage of development and can be distinguished by differential expression of specific surface markers. Notably, CD235a/b+ mesoderm gives rise to yolk sac (YS) hematopoietic lineages and left ventricular cardiomyocytes, while CD235a/b- mesoderm generates definitive hematopoiesis and atrial cardiomyocytes. However, CD235a/b alone does not segregate hematopoietic from cardiac fate, resulting in the failure to detect potentially contaminating cardiovascular mesoderm within hematopoietic mesoderm cultures. To resolve this, we conducted a reanalysis of existing transcriptomic datasets to identify additional surface markers that can distinguish between hematopoietic and cardiac mesoderm subsets. Sorting mesoderm based on candidate markers demonstrated that CD1d marks definitive hematopoietic mesoderm, CD49c marks both YS hematopoietic and cardiac mesoderm, while CD49f marks only cardiac mesoderm. By monitoring the early stage differentiating populations with these markers, we have found that CD235a/b- definitive hematopoietic mesoderm often contains contaminating CD49c+ YS mesoderm and CD49f+ cardiac mesoderm. We next sought to improve the efficiency of induction of CD1d+ mesoderm through staged manipulation of key signaling pathways. With this approach, we identified a set of conditions that gives rise to highly enriched populations of CD1d+ mesoderm with significantly reduced levels of contaminating CD49c+ and CD49f+ mesoderm. Upon further culture, this CD1d+ mesoderm generated CD34+ CD43- hemogenic endothelial cells with robust B cell potential comparable to that of cord blood progenitors. Collectively, these findings have enabled the precise monitoring of mesoderm development and the efficient specification of distinct hematopoietic mesoderm populations and their derivatives.