Background Acute rheumatic fever (ARF) and its chronic sequelae, rheumatic heart disease (RHD) contributes to valvular dysfunction and significant cardiovascular disability and endocardial damage is considered the primary pathophysiological mechanism underlying ARF. This study examined peripheral blood markers of endothelial injury and function in ARF and RHD patients and compared them to healthy controls. Method In this prospective observational study, the levels of collagen intermediates, matrix metalloproteinases, tissue inhibitors of matrix metalloproteinases, brain natriuretic peptide, Anti-DNaseB, VEGF, E-selectin, VCAM, and ICAM in circulation were estimated. The study also isolated hemangioblastic and monocytic endothelial progenitor cells and their respective microvesicles from the peripheral blood of patients and control samples. Results Procollagen type I carboxy-terminal propeptide, cross-linked c-telopeptide of type I, and procollagen III c-terminal propeptide levels were higher in RHD subjects compared to patients with ARF. The ARF patients had the highest levels of matrix metalloproteinases 10 (MMP-10) followed by chronic patients and healthy controls. The ratio of tissue inhibitors of matrix metalloproteinases TIMP-1 and MMP-10 was lowest in healthy controls. At the cellular level, there were higher number of monocytic endothelial progenitor cells (EPCs) in ARF subjects as compared to healthy controls. For hemangioblastic EPCs, there was no significant difference between chronic subjects and healthy controls, though their early subtype was higher in chronic subjects. The hemangioblastic EPCs microvesicles were more abundant in ARF compared to RHD patients. Conclusion The greater number of EPCs and respective microvesicles confirm the continued disruption of the endothelium in ARF, and during the progression of the disease, the majority of EPCs undergo apoptosis. Obituary Statement This study was conceived and designed by SR, PU, and Prof. Rajnish Juneja, Professor at AIIMS. Prof. Rajnish Juneja expired in April 2018 while the study was ongoing (1). Mr. Suran Nambisan, a research fellow at NII, was part of the team who initiated the experimental work. Dr. Suran Nambisan expired in January 2023. This paper is dedicated to both of them. It was the profound love for mankind and unwavering dedication to perfection by Prof. Rajnish Juneja that brought together a remarkable team to undertake this study. Dr. Suran Nambisan embarked on his professional research journey by successfully establishing and standardizing a few intricate protocols used in this study.

Hemogenic endothelium (HE) is the main source of blood cells in the embryo. To improve blood manufacturing from human pluripotent stem cells (hPSCs), it is essential to define the molecular determinants that enhance HE specification and promote development of the desired blood lineage from HE. Here, using SOX18-inducible hPSCs, we revealed that SOX18 forced expression at the mesodermal stage, in contrast to its homolog SOX17, has minimal effects on arterial specification of HE, expression of HOXA genes and lymphoid differentiation. However, forced expression of SOX18 in HE during endothelial-to-hematopoietic transition (EHT) greatly increases NK versus T cell lineage commitment of hematopoietic progenitors (HPs) arising from HE predominantly expanding CD34+CD43+CD235a/CD41a-CD45- multipotent HPs and altering the expression of genes related to T cell and Toll-like receptor signaling. These studies improve our understanding of lymphoid cell specification during EHT and provide a new tool for enhancing NK cell production from hPSCs for immunotherapies.
© 2023 The Author(s).

Muscle injuries, degenerative diseases and other lesions negatively affect functioning of human skeletomuscular system and thus quality of life. Therefore, the investigation of molecular mechanisms, stimulating myogenic differentiation of primary skeletal-muscle-derived mesenchymal stem/stromal cells (SM-MSCs), is actual and needed. The aim of the present study was to investigate the myogenic differentiation of CD56 (neural cell adhesion molecule, NCAM)-positive and -negative SM-MSCs and their response to the non-cytotoxic heat stimulus. The SM-MSCs were isolated from the post operation muscle tissue, sorted by flow cytometer according to the CD56 biomarker and morphology, surface profile, proliferation and myogenic differentiation has been investigated. Data show that CD56(+) cells were smaller in size, better proliferated and had significantly higher levels of CD146 (MCAM) and CD318 (CDCP1) compared with the CD56(-) cells. At control level, CD56(+) cells significantly more expressed myogenic differentiation markers MYOD1 and myogenin (MYOG) and better differentiated to the myogenic direction. The non-cytotoxic heat stimulus significantly stronger stimulated expression of myogenic markers in CD56(+) than in CD56(-) cells that correlated with the multinucleated cell formation. Data show that regenerative properties of CD56(+) SM-MSCs can be stimulated by an extracellular stimulus and be used as a promising skeletal muscle regenerating tool in vivo.

Endothelial-to-hematopoietic transition (EHT) is a unique morphogenic event in which flat, adherent hemogenic endothelial (HE) cells acquire round, non-adherent blood cell morphology. Investigating the mechanisms of EHT is critical for understanding the development of hematopoietic stem cells (HSCs) and the entirety of the adult immune system, and advancing technologies for manufacturing blood cells from human pluripotent stem cells (hPSCs). Here we describe a protocol to (a) generate and isolate subsets of HE from hPSCs, (b) assess EHT and hematopoietic potential of HE subsets in bulk cultures and at the single-cell level, and (c) evaluate the role of NOTCH signaling during HE specification and EHT. The generation of HE from hPSCs and EHT bulk cultures are performed in xenogen- and feeder-free system, providing the unique advantage of being able to investigate the role of individual signaling factors during EHT and the definitive lympho-myeloid cell specification from hPSCs.
© 2022. Springer Science+Business Media, LLC, part of Springer Nature.

SOX17 has been implicated in arterial specification and the maintenance of hematopoietic stem cells (HSCs) in the murine embryo. However, knowledge about molecular pathways and stage-specific effects of SOX17 in humans remains limited. Here, using SOX17-knockout and SOX17-inducible human pluripotent stem cells (hPSCs), paired with molecular profiling studies, we reveal that SOX17 is a master regulator of HOXA and arterial programs in hemogenic endothelium (HE) and is required for the specification of HE with robust lympho-myeloid potential and DLL4+CXCR4+ phenotype resembling arterial HE at the sites of HSC emergence. Along with the activation of NOTCH signaling, SOX17 directly activates CDX2 expression, leading to the upregulation of the HOXA cluster genes. Since deficiencies in HOXA and NOTCH signaling contribute to the impaired in vivo engraftment of hPSC-derived hematopoietic cells, the identification of SOX17 as a key regulator linking arterial and HOXA programs in HE may help to program HSC fate from hPSCs.
Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.