Stem Cell Neurodevelopmental Solutions for Restorative Treatments of the Human Trunk and Spine

The ability to reliably repair spinal cord injuries (SCI) will be one of the greatest human achievements realized in regenerative medicine. Until recently, the cellular path to this goal has been challenging. However, as detailed developmental principles are revealed in mouse and human models, their application in the stem cell community brings trunk and spine embryology into efforts to advance human regenerative medicine. New models of posterior embryo development identify neuromesodermal progenitors (NMPs) as a major bifurcation point in generating the spinal cord and somites and is leading to production of cell types with the full range of axial identities critical for repair of trunk and spine disorders. This is coupled with organoid technologies including assembloids, circuitoids, and gastruloids. We describe a paradigm for applying developmental principles towards the goal of cell-based restorative therapies to enable reproducible and effective near-term clinical interventions.

Myocardial Accumulations of Reg3A, Reg3γ and Oncostatin M Are Associated with the Formation of Granulomata in Patients with Cardiac Sarcoidosis

Cardiac sarcoidosis (CS) is a poorly understood disease and is characterized by the focal accumulation of immune cells, thus leading to the formation of granulomata (GL). To identify the developmental principles of fatal GL, fluorescence microscopy and Western blot analysis of CS and control patients is presented here. CS is visualized macroscopically by positron emission tomography (PET)/ computed tomography (CT). A battery of antibodies is used to determine structural, cell cycle and inflammatory markers. GL consist of CD68+, CD163+ and CD206+ macrophages surrounded by T-cells within fibrotic areas. Cell cycle markers such as phospho-histone H3, phospho-Aurora and Ki67 were moderately present; however, the phosphorylated ERM (ezrin, radixin and moesin) and Erk1/2 proteins, strong expression of the myosin motor protein and the macrophage transcription factor PU.1 indicate highly active GL. Mild apoptosis is consistent with PI3 kinase and Akt activation. Massive amounts of the IL-1R antagonist reflect a mild activation of stress and inflammatory pathways in GL. High levels of oncostatin M and the Reg3A and Reg3γ chemokines are in accordance with macrophage accumulation in areas of remodeling cardiomyocytes. We conclude that the formation of GL occurs mainly through chemoattraction and less by proliferation of macrophages. Furthermore, activation of the oncostatin/Reg3 axis might help at first to wall-off substances but might initiate the chronic development of heart failure.

In vivo dissection of a clustered-CTCF domain boundary reveals developmental principles of regulatory insulation

Vertebrate genomes organize into topologically associating domains (TADs), delimited by boundaries that insulate regulatory elements from non-target genes. However, how boundary function is established is not well understood. Here, we combine genome-wide analyses and transgenic mouse assays to dissect the regulatory logic of clustered-CTCF boundaries in vivo, interrogating their function at multiple levels: chromatin interactions, transcription and phenotypes. Individual CTCF binding sites (CBS) deletions revealed that the characteristics of specific sites can outweigh other factors like CBS number and orientation. Combined deletions demonstrated that CBS cooperate redundantly and provide boundary robustness. We show that divergent CBS signatures are not strictly required for effective insulation and that chromatin loops formed by non-convergently oriented sites could be mediated by a loop interference mechanism. Further, we observe that insulation strength constitutes a quantitative modulator of gene expression and phenotypes. Our results highlight the modular nature of boundaries and their control over developmental processes.

Fetal liver hematopoiesis: from development to delivery

Clinical transplants of hematopoietic stem cells (HSC) can provide a lifesaving therapy for many hematological diseases; however, therapeutic applications are hampered by donor availability. In vivo, HSC exist in a specified microenvironment called the niche. While most studies of the niche focus on those residing in the bone marrow (BM), a better understanding of the fetal liver niche during development is vital to design human pluripotent stem cell (PSC) culture and may provide valuable insights with regard to expanding HSCs ex vivo for transplantation. This review will discuss the importance of the fetal liver niche in HSC expansion, a feat that occurs during development and has great clinical potential. We will also discuss emerging approaches to generate expandable HSC in cell culture that attain more complexity in the form of cells or organoid models in combination with engineering and systems biology approaches. Overall, delivering HSC by charting developmental principles will help in the understanding of the molecular and biological interactions between HSCs and fetal liver cells for their controlled maturation and expansion.

Application of developmental principles for spinal cord repair after injury

The superiority of the mammalian central nervous system (CNS) among other vertebrates does not involve an advanced capacity for regeneration and any insult results to irreversible function loss. Spinal cord injury (SCI) is one example of CNS trauma affecting thousands of individuals, mostly young, each year. Despite enormous progress in our comprehension of the molecular and cellular mechanisms underlying the pathophysiology after SCI, also providing targets for therapeutic interventions, so far, no efficient therapy exists, emphasizing the necessity for further research. A breadth of studies have demonstrated that, after SCI, principles of development come at play either to promote or to prohibit spontaneous regeneration and their accurate manipulation holds promise toward functional recovery. In this overview, some of the most recent and important studies are discussed that offer explicitly novel input from the field of development to the field of CNS repair regarding the modification of the inhibitory environment of the injured spinal cord – majorly referring to the glial scar – the activation of endogenous cell populations such as ependymal stem cells and oligodendrocyte precursor cells, and the developmental transcriptional program that is transiently activated in neurons after injury. Furthermore, current advances in stem cell technology are highlighted in terms of refinement and precise design of the appropriate stem cell population to be transplanted not only for cell replacement but also for modulation of the host environment. As single-dimension applications were not yet clinically successful, combinatorial strategies tackling more than one targets are suggested as more auspicious.

Developmental sequences for observing and assessing forceful kicking

While football/soccer is the most influential sport in the world, it is surprising that developmental sequences of forceful kicking have not been adequately described and validated in the literature. The purpose of this study was to explore potential developmental sequences for forceful kicking using a prelongitudinal screening method. Data were derived from videotapes of 255 children (girls n = 138, boys: n = 117), ages 4–11 years. Seven potential component sequences in their respective developmental order were initially proposed based on biomechanical and motor developmental principles. Each participant was digitally videoed performing five kicks with maximal effort. Trained research staff coded the initial seven components for each kick and the mode of each participant’s five kicks was used for data analysis. Component level probability curves for each component sequence across age were evaluated using the threshold based generalized partial credit model (Muraki, 1992) within the item response theory framework. As developmental theory would indicate, component levels generally increased with age for most components. Six component ordinal sequence progressions met model requirements (Rel = 0.88, item fit; p > 0.05). Ordinal levels for two components ( Knee action and Follow-through) were altered based on initial empirical model structure fit and the Ball contact component was removed based on a lack of model fit. This study provides sufficient cross-sectional evidence for six component developmental sequences that adequately describe the development of kicking using cross-sectional data. Longitudinal data are required to provide further developmental validation for these sequences.