Wound healing, cellular regeneration and plasticity: the elegans way

Understanding the molecular mechanism of regeneration through apoptosis-induced compensatory proliferation studies - updates and future aspects

AICP is a crucial process that maintaining tissue homeostasis and regeneration. In the past, cell death was perceived merely as a means to discard cells without functional consequences. However, during regeneration, effector caspases orchestrate apoptosis, releasing signals that activate stem cells, thereby compensating for tissue loss across various animal models. Despite significant progress, the activation of Wnt3a by caspase-3 remains a focal point of research gaps in AICP mechanisms, spanning from lower to higher regenerative animals. This inquiry into the molecular intricacies of caspase-3-induced Wnt3a activation contributes to a deeper understanding of the links between regeneration and cancer mechanisms. Our report provides current updates on AICP pathways, delineating research gaps and highlighting the potential for future investigations aimed at enhancing our comprehension of this intricate process.

The Function of the Immune System, Beyond Strategies Based on Cell-Autonomous Mechanisms, Determines Cancer Development: Immune Response and Cancer Development

Although cancer remains a challenging disease to treat, early detection and removal of primary tumors through surgery or chemotherapy/radiotherapy can offer hope for patients. The privilege paradigm in cancer biology suggests that cell-autonomous mechanisms play a central role in tumorigenesis. According to this paradigm, these cellular mechanisms are the primary focus for the prevention and treatment of cancers. However, this point of view does not present a comprehensive theory for the initiation of cancer and an effective therapeutic strategy. Having an incomplete understanding of the etiology of cancer, it is essential to re-examine previous assumptions about carcinogenesis and develop new, practical theories that can account for all available clinical and experimental evidence. This will not only help to gain a better understanding of the disease, but also offer new avenues for treatment. This review provides evidence suggesting a shift in focus from a cell-autonomous mechanism to systemic mechanisms, particularly the immune system, that are involved in cancer formation.

Functional analysis of cell plasticity using single-cell technologies

Metazoan organisms are heterocellular systems composed of hundreds of different cell types, which arise from an isogenic genome through differentiation. Cellular 'plasticity' further enables cells to alter their fate in response to exogenous cues and is involved in a variety of processes, such as wound healing, infection, and cancer. Recent advances in cellular model systems, high-dimensional single-cell technologies, and lineage tracing have sparked a renaissance in plasticity research. Here, we discuss the definition of cell plasticity, evaluate state-of-the-art model systems and techniques to study cell-fate dynamics, and explore the application of single-cell technologies to obtain functional insights into cell plasticity in healthy and diseased tissues. The integration of advanced biomimetic model systems, single-cell technologies, and high-throughput perturbation studies is enabling a new era of research into non-genetic plasticity in metazoan systems.

Hepatic insulin synthesis increases in rat models of diabetes mellitus type 1 and 2 differently

Insulin-positive (+) cells (IPCs), detected in multiple organs, are of great interest as a probable alternative to ameliorate pancreatic beta-cells dysfunction and insulin deficiency in diabetes. Liver is a potential source of IPCs due to it common embryological origin with pancreas. We previously demonstrated the presence of IPCs in the liver of healthy and diabetic rats, but detailed description and analysis of the factors, which potentially can induced ectopic hepatic expression of insulin in type 1 (T1D) and type 2 diabetes (T2D), were not performed. In present study we evaluate mass of hepatic IPCs in the rat models of T1D and T2D and discuss factors, which may stimulate it generation: glycaemia, organ injury, involving of hepatic stem/progenitor cell compartment, expression of transcription factors and inflammation. Quantity of IPCs in the liver was up by 1.7-fold in rats with T1D and 10-fold in T2D compared to non-diabetic (ND) rats. We concluded that ectopic hepatic expression of insulin gene is activated by combined action of a number of factors, with inflammation playing a decision role.

The role of senescence in cellular plasticity: Lessons from regeneration and development and implications for age-related diseases

Senescence is a cellular state which involves cell cycle arrest and a proinflammatory phenotype, and it has traditionally been associated with cellular and organismal aging. However, increasing evidence suggests key roles in tissue growth and regrowth, especially during development and regeneration. Conversely, cellular plasticity-the capacity of cells to undergo identity change, including differentiation and dedifferentiation-is associated with development and regeneration but is now being investigated in the context of age-related diseases such as Alzheimer disease. Here, we discuss the paradox of the role for cellular senescence in cellular plasticity: senescence can act as a cell-autonomous barrier and a paracrine driver of plasticity. We provide a conceptual framework for integrating recent data and use the interplay between cellular senescence and plasticity to provide insight into age-related diseases. Finally, we argue that age-related diseases can be better deciphered when senescence is recognized as a core mechanism of regeneration and development.

Epithelial-Mesenchymal Transition (EMT): The Type-2 EMT in Wound Healing, Tissue Regeneration and Organ Fibrosis

The epithelial–mesenchymal transition (EMT) is an essential event during cell development, in which epithelial cells acquire mesenchymal fibroblast-like features including reduced intercellular adhesion and increased motility. EMT also plays a key role in wound healing processes, which are mediated by inflammatory cells and fibroblasts. These cells secrete specific factors that interact with molecules of the extracellular matrix (ECM) such as collagens, laminins, elastin and tenascins. Wound healing follows four distinct and successive phases characterized by haemostasis, inflammation, cell proliferation and finally tissue remodeling. EMT is classified into three diverse subtypes: type-1 EMT, type-2 EMT and type-3 EMT. Type-1 EMT is involved in embryogenesis and organ development. Type-2 EMT is associated with wound healing, tissue regeneration and organ fibrosis. During organ fibrosis, type-2 EMT occurs as a reparative-associated process in response to ongoing inflammation and eventually leads to organ destruction. Type-3 EMT is implicated in cancer progression, which is linked to the occurrence of genetic and epigenetic alterations, in detail the ones promoting clonal outgrowth and the formation of localized tumors. The current review aimed at exploring the role of EMT process with particular focus on type-2 EMT in wound healing, fibrosis and tissue regeneration, as well as some recent progresses in the EMT and tissue regeneration field, including the modulation of EMT by biomaterials.

The Diversity of Muscles and Their Regenerative Potential across Animals

Cells with contractile functions are present in almost all metazoans, and so are the related processes of muscle homeostasis and regeneration. Regeneration itself is a complex process unevenly spread across metazoans that ranges from full-body regeneration to partial reconstruction of damaged organs or body tissues, including muscles. The cellular and molecular mechanisms involved in regenerative processes can be homologous, co-opted, and/or evolved independently. By comparing the mechanisms of muscle homeostasis and regeneration throughout the diversity of animal body-plans and life cycles, it is possible to identify conserved and divergent cellular and molecular mechanisms underlying muscle plasticity. In this review we aim at providing an overview of muscle regeneration studies in metazoans, highlighting the major regenerative strategies and molecular pathways involved. By gathering these findings, we wish to advocate a comparative and evolutionary approach to prompt a wider use of “non-canonical” animal models for molecular and even pharmacological studies in the field of muscle regeneration.

Nematode Autotomy Requires Molting and Entails Tissue Healing without Obvious Regeneration

Autotomy in C. elegans, which results in the severing of the body into two fragments, has been observed as a response to late larval worm-star formation after exposure to a bacterial surface pathogen. It was found that autotomy can occur in both hermaphroditic and gonochoristic nematode species, and during either the L3 or the L4 molt. Severing was hypothesized to be driven by a ‘balloon-twisting’ mechanism during molting but was found to be independent of lethargus-associated flipping. Extensive healing and apparent tissue fusion were seen at the site of scission. No obvious regeneration of lost body parts was seen in either L4 or adult truncated worms. A variety of mutants defective in processes of cell death, healing, regeneration, responses to damage, stress or pathogens were found to be competent to autotomize. Mutants specifically defective in autotomy have yet to be found. Autotomy may represent a modification of the essential normal process of molting.

Developmental Plasticity and Cellular Reprogramming in Caenorhabditis elegans

While Caenorhabditis elegans was originally regarded as a model for investigating determinate developmental programs, landmark studies have subsequently shown that the largely invariant pattern of development in the animal does not reflect irreversibility in rigidly fixed cell fates. Rather, cells at all stages of development, in both the soma and germline, have been shown to be capable of changing their fates through mutation or forced expression of fate-determining factors, as well as during the normal course of development. In this chapter, we review the basis for natural and induced cellular plasticity in C. elegans We describe the events that progressively restrict cellular differentiation during embryogenesis, starting with the multipotency-to-commitment transition (MCT) and subsequently through postembryonic development of the animal, and consider the range of molecular processes, including transcriptional and translational control systems, that contribute to cellular plasticity. These findings in the worm are discussed in the context of both classical and recent studies of cellular plasticity in vertebrate systems.