Schwann cell precursors (SCPs) are multipotent embryonic progenitors covering all developing peripheral nerves. These nerves grow and navigate with unprecedented precision, delivering SCP progenitors ...to almost all locations in the embryonic body. Within specific developing tissues, SCPs detach from nerves and generate neuroendocrine cells, autonomic neurons, mature Schwann cells, melanocytes and other cell types. These properties of SCPs evoke resemblances between them and their parental population, namely, neural crest cells. Neural crest cells are incredibly multipotent migratory cells that revolutionized the course of evolution in the lineage of early chordate animals. Given this similarity and recent data, it is possible to hypothesize that proto-neural crest cells are similar to SCPs spreading along the nerves. Here, we review the multipotency of SCPs, the signals that govern them, their potential therapeutic value, SCP's embryonic origin and their evolutionary connections.
We dedicate this article to the memory of Wilhelm His,
the father of the microtome and “Zwischenstrang”,
currently known as the neural crest.
•There are similarities between neural crest cells and Schwann cell precursors (SCPs).•Peripheral nerves and SCPs play non-canonical roles in the body.•SCP are multipotent and give rise to a number of neural crest-derived cell types.•Plasticity of SCPs evokes evolutionary discussions about neural crest origin.•Schwann cell lineage plays an important role in development of different pathologies.
Supracellular contractions propel migration Adameyko, Igor
Science (American Association for the Advancement of Science),
10/2018, Letnik:
362, Številka:
6412
Journal Article
Recenzirano
Cytoskeletal cords connecting cells at the back of cell groups enable directional migration
Constructing multicellular bodies, starting from a single-cell zygote, often requires the movement of cells ...across considerable distances, which is achieved through cell migration. During embryonic development, as well as in healing and regeneration, cells travel across diverse terrains, which dictates the character of navigation (
1
). Cancer cells metastasize and migrate into healthy organs, and knowledge of their migration strategies could be important to identify targets to treat advanced disease (
2
). Some migratory cells cover large distances individually (
3
), whereas others migrate in groups, with leaders and followers being directed by chemical signals (chemotaxis) (
4
,
5
). The exchange of information and resulting motility of such groups has been enigmatic. Moreover, the driving force of collective cell migration has been considered a sum of migratory and signaling activities of individually participating cells. However, according to a study on page 339 of this issue by Shellard
et al.
(
6
), collective cell migration requires formation of cytoskeletal structures that span through adjoining cells at the rear of a cell group to coordinate, orient, and propel the entire group. This mechanism of collective cell migration could be applicable to cancer metastasis and wound healing and might change our understanding of developmental migration.
Highlights In the article by Petersen and Adameyko, the story of Schwann cell precursor’s (SCPs) multipotency develops step by step informing the reader about the key role of SCPs in producing ...various cell types in a vertebrate embryo. • Recently, nerve-associated SCPs turned out to be a multipotent neural crest-derived cell type. • SCPs generate melanocytes, parasympathetic and enteric neurons, Schwann cells and mesenchymal cells. • Evolutionary, SCPs may represent the most ancient version of neural crest dispersal throughout the body.
An essential prerequisite for the survival of an organism is the ability to detect and respond to aversive stimuli. Current belief is that noxious stimuli directly activate nociceptive sensory nerve ...endings in the skin. We discovered a specialized cutaneous glial cell type with extensive processes forming a mesh-like network in the subepidermal border of the skin that conveys noxious thermal and mechanical sensitivity. We demonstrate a direct excitatory functional connection to sensory neurons and provide evidence of a previously unknown organ that has an essential physiological role in sensing noxious stimuli. Thus, these glial cells, which are intimately associated with unmyelinated nociceptive nerves, are inherently mechanosensitive and transmit nociceptive information to the nerve.
Loss of tissue attachment as a consequence of bacterial infection and inflammation represents the main therapeutic target for the treatment of periodontitis. Cementoblasts, the cells that produce the ...mineralized tissue, cementum, that is responsible for connecting the soft periodontal tissue to the tooth, are a key cell type for maintaining/restoring tissue attachment following disease. Here, we identify two distinct stem cell populations that contribute to cementoblast differentiation at different times. During postnatal development, cementoblasts are formed from perivascular‐derived cells expressing CD90 and perivascular‐associated cells that express Axin2. During adult homeostasis, only Wnt‐responsive Axin2+ cells form cementoblasts but following experimental induction of periodontal disease, CD90+ cells become the main source of cementoblasts. We thus show that different populations of resident stem cells are mobilized at different times and during disease to generate precursors for cementoblast differentiation and thus provide an insight into the targeting cells resident cells for novel therapeutic approaches. The differentiation of these stem cells into cementoblasts is however inhibited by bacterial products such as lipopolysaccharides, emphasizing that regeneration of periodontal ligament soft tissue and restoration of attachment will require a multipronged approach.
During homeostasis, two cells populations (Axin2+ and CD90+ cells) differentiate into cementoblasts in the periodontium. In adults, only Axin2+ cells continue contributing to cementoblast formation, whereas CD90+ cells are not necessary during adult homeostasis. Following induction of periodontitis, CD90+ cells are stimulated to differentiate into cementoblasts
Neural crest cells are embryonic progenitors that generate numerous cell types in vertebrates. With single-cell analysis, we show that mouse trunk neural crest cells become biased toward neuronal ...lineages when they delaminate from the neural tube, whereas cranial neural crest cells acquire ectomesenchyme potential dependent on activation of the transcription factor
The choices that neural crest cells make to become sensory, glial, autonomic, or mesenchymal cells can be formalized as a series of sequential binary decisions. Each branch of the decision tree involves initial coactivation of bipotential properties followed by gradual shifts toward commitment. Competing fate programs are coactivated before cells acquire fate-specific phenotypic traits. Determination of a specific fate is achieved by increased synchronization of relevant programs and concurrent repression of competing fate programs.
During early development, cartilage provides shape and stability to the embryo while serving as a precursor for the skeleton. Correct formation of embryonic cartilage is hence essential for healthy ...development. In vertebrate cranial cartilage, it has been observed that a flat and laterally extended macroscopic geometry is linked to regular microscopic structure consisting of tightly packed, short, transversal clonar columns. However, it remains an ongoing challenge to identify how individual cells coordinate to successfully shape the tissue, and more precisely which mechanical interactions and cell behaviors contribute to the generation and maintenance of this columnar cartilage geometry during embryogenesis. Here, we apply a three-dimensional cell-based computational model to investigate mechanical principles contributing to column formation. The model accounts for clonal expansion, anisotropic proliferation and the geometrical arrangement of progenitor cells in space. We confirm that oriented cell divisions and repulsive mechanical interactions between cells are key drivers of column formation. In addition, the model suggests that column formation benefits from the spatial gaps created by the extracellular matrix in the initial configuration, and that column maintenance is facilitated by sequential proliferative phases. Our model thus correctly predicts the dependence of local order on division orientation and tissue thickness. The present study presents the first cell-based simulations of cell mechanics during cranial cartilage formation and we anticipate that it will be useful in future studies on the formation and growth of other cartilage geometries.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ABSTRACT
Articular cartilage has little regenerative capacity. Recently, genetic lineage tracing experiments have revealed chondrocyte progenitors at the articular surface. We further characterized ...these progenitors by using in vivo genetic approaches. Histone H2B–green fluorescent protein retention revealed that superficial cells divide more slowly than underlying articular chondrocytes. Clonal genetic tracing combined with immunohistochemistry revealed that superficial cells renew their number by symmetric division, express mesenchymal stem cell markers, and generate chondrocytes via both asymmetric and symmetric differentiation. Quantitative analysis of cellular kinetics, in combination with phosphotungstic acid–enhanced micro–computed tomography, showed that superficial cells generate chondrocytes and contribute to the growth and reshaping of articular cartilage. Furthermore, we found that cartilage renewal occurs as the progeny of superficial cells fully replace fetal chondrocytes during early postnatal life. Thus, superficial cells are self‐renewing progenitors that are capable of maintaining their own population and fulfilling criteria of unipotent adult stem cells. Furthermore, the progeny of these cells reconstitute adult articular cartilage de novo, entirely substituting fetal chondrocytes.—Li, L., Newton, P. T., Bouderlique, T., Sejnohova, M., Zikmund, T., Kozhemyakina, E., Xie, M., Krivanek, J., Kaiser, J., Qian, H., Dyachuk, V., Lassar, A. B., Warman, M. L., Barenius, B., Adameyko, I., Chagin, A. S. Superficial cells are self‐renewing chondrocyte progenitors, which form the articular cartilage in juvenile mice. FASEB J. 31, 1067–1084 (2017). www.fasebj.org
Branching morphogenesis governs the formation of many organs such as lung, kidney, and the neurovascular system. Many studies have explored system-specific molecular and cellular regulatory ...mechanisms, as well as self-organizing rules underlying branching morphogenesis. However, in addition to local cues, branched tissue growth can also be influenced by global guidance. Here, we develop a theoretical framework for a stochastic self-organized branching process in the presence of external cues. Combining analytical theory with numerical simulations, we predict differential signatures of global vs. local regulatory mechanisms on the branching pattern, such as angle distributions, domain size, and space-filling efficiency. We find that branch alignment follows a generic scaling law determined by the strength of global guidance, while local interactions influence the tissue density but not its overall territory. Finally, using zebrafish innervation as a model system, we test these key features of the model experimentally. Our work thus provides quantitative predictions to disentangle the role of different types of cues in shaping branched structures across scales.
Mesenchymal stem cells occupy niches in stromal tissues where they provide sources of cells for specialized mesenchymal derivatives during growth and repair. The origins of mesenchymal stem cells ...have been the subject of considerable discussion, and current consensus holds that perivascular cells form mesenchymal stem cells in most tissues. The continuously growing mouse incisor tooth offers an excellent model to address the origin of mesenchymal stem cells. These stem cells dwell in a niche at the tooth apex where they produce a variety of differentiated derivatives. Cells constituting the tooth are mostly derived from two embryonic sources: neural crest ectomesenchyme and ectodermal epithelium. It has been thought for decades that the dental mesenchymal stem cells giving rise to pulp cells and odontoblasts derive from neural crest cells after their migration in the early head and formation of ectomesenchymal tissue. Here we show that a significant population of mesenchymal stem cells during development, self-renewal and repair of a tooth are derived from peripheral nerve-associated glia. Glial cells generate multipotent mesenchymal stem cells that produce pulp cells and odontoblasts. By combining a clonal colour-coding technique with tracing of peripheral glia, we provide new insights into the dynamics of tooth organogenesis and growth.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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