[Jan. 5] 88th IRCMS Seminar

January 11 2023

We would like to inform you that the 88th IRCMS seminar has been scheduled as below.
* This IRCMS seminar is open to everyone.

Date      : January 5, 2023 (Thursday)

Time      : 11:00 - 12:00
              * Zoom online seminar

Speaker : Dr. Momoko Yoshimoto
                University of Texas Health Science Center at Houston

Title        :  Multiple waves of hematopoiesis in the mouse embryo constitute adult immune system

Abstract :

It has been considered that all blood cells are derived from hematopoietic stem cells (HSCs). However, this stem cell dogma has been challenged by recent findings that some tissue resident immune cells originate from fetal precursors but are not produced by adult hematopoietic program. During embryonic development, many waves of blood production has been reported before the first HSC emergence. In addition to definitive type erythro-myeloid progenitors, T- and B- lymphoid potential has been recognized at the pre-HSC period; however, it has been unresolved whether   this lymphoid potential is associated with the development of HSCs at the later stage or independently arises from HSCs, and to what extent these fetal-derived lymphoid cells persist into the postnatal life.

Here, utilizing lineage tracing mouse models and transplantation studies, we found that significant percent of definitive hematopoietic cells, including multipotent progenitors and T&B lymphocytes, are derived from endothelial cells independently of HSC and persist over 6 months of age. Additionally, the majority of peritoneal B-1a cells are HSC-independent for life. Our discovery of extensive HSC-independent definitive immune cells in adults attests to the complex blood developmental dynamics through embryo to adult that underpin the immune system and challenges the paradigm of HSC theory in hematology.

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