Myofibroblasts and mechano-regulation of connective tissue remodelling
01 May 2002-Nature Reviews Molecular Cell Biology (Nature Publishing Group)-Vol. 3, Iss: 5, pp 349-363
TL;DR: It is clear that the understanding of the myofibroblast — its origins, functions and molecular regulation — will have a profound influence on the future effectiveness not only of tissue engineering but also of regenerative medicine generally.
Abstract: During the past 20 years, it has become generally accepted that the modulation of fibroblastic cells towards the myofibroblastic phenotype, with acquisition of specialized contractile features, is essential for connective-tissue remodelling during normal and pathological wound healing. Yet the myofibroblast still remains one of the most enigmatic of cells, not least owing to its transient appearance in association with connective-tissue injury and to the difficulties in establishing its role in the production of tissue contracture. It is clear that our understanding of the myofibroblast its origins, functions and molecular regulation will have a profound influence on the future effectiveness not only of tissue engineering but also of regenerative medicine generally.
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TL;DR: Naive mesenchymal stem cells are shown here to specify lineage and commit to phenotypes with extreme sensitivity to tissue-level elasticity, consistent with the elasticity-insensitive commitment of differentiated cell types.
12,204 citations
Cites background from "Myofibroblasts and mechano-regulati..."
...…Sweeney,1 and Dennis E. Discher1,2,3,4,* 1Pennsylvania Muscle Institute 2School of Engineering and Applied Science 3Cell & Molecular Biology Graduate Group 4Physics Graduate Group University of Pennsylvania, Philadelphia, PA 19104, USA *Contact: discher@seas.upenn.edu DOI 10.1016/j.cell.2006.06.044...
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...…gels and wrinkling-silicone sheets also suggest some responsiveness to the physical state of the matrix (Hinz et al., 2001; Nakagawa et al., 1989; Tomasek et al., 2002; Wozniak et al., 2003), but gel porosity and film topography complicate identification of possible contributions of substrate…...
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TL;DR: The paradoxical roles of the tumor microenvironment during specific stages of cancer progression and metastasis are discussed, as well as recent therapeutic attempts to re-educate stromal cells within the TME to have anti-tumorigenic effects.
Abstract: Cancers develop in complex tissue environments, which they depend on for sustained growth, invasion and metastasis. Unlike tumor cells, stromal cell types within the tumor microenvironment (TME) are genetically stable and thus represent an attractive therapeutic target with reduced risk of resistance and tumor recurrence. However, specifically disrupting the pro-tumorigenic TME is a challenging undertaking, as the TME has diverse capacities to induce both beneficial and adverse consequences for tumorigenesis. Furthermore, many studies have shown that the microenvironment is capable of normalizing tumor cells, suggesting that re-education of stromal cells, rather than targeted ablation per se, may be an effective strategy for treating cancer. Here we discuss the paradoxical roles of the TME during specific stages of cancer progression and metastasis, as well as recent therapeutic attempts to re-educate stromal cells within the TME to have anti-tumorigenic effects.
5,396 citations
TL;DR: Fibroblasts are a key determinant in the malignant progression of cancer and represent an important target for cancer therapies.
Abstract: Tumours are known as wounds that do not heal - this implies that cells that are involved in angiogenesis and the response to injury, such as endothelial cells and fibroblasts, have a prominent role in the progression, growth and spread of cancers. Fibroblasts are associated with cancer cells at all stages of cancer progression, and their structural and functional contributions to this process are beginning to emerge. Their production of growth factors, chemokines and extracellular matrix facilitates the angiogenic recruitment of endothelial cells and pericytes. Fibroblasts are therefore a key determinant in the malignant progression of cancer and represent an important target for cancer therapies.
4,232 citations
Cites background from "Myofibroblasts and mechano-regulati..."
...The important functions of fibroblasts include the deposition of extracellular matrix (ECM), regulation of epithelial differentiation, regulation of inflammation, and involvement in wound healin...
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TL;DR: Current understanding of the cellular and molecular mechanisms of fibrogenesis is explored and components of the renin–angiotensin–aldosterone system (ANG II) have been identified as important regulators of fibrosis and are being investigated as potential targets of antifibrotic drugs.
Abstract: Fibrosis is defined by the overgrowth, hardening, and/or scarring of various tissues and is attributed to excess deposition of extracellular matrix components including collagen. Fibrosis is the end result of chronic inflammatory reactions induced by a variety of stimuli including persistent infections, autoimmune reactions, allergic responses, chemical insults, radiation, and tissue injury. Although current treatments for fibrotic diseases such as idiopathic pulmonary fibrosis, liver cirrhosis, systemic sclerosis, progressive kidney disease, and cardiovascular fibrosis typically target the inflammatory response, there is accumulating evidence that the mechanisms driving fibrogenesis are distinct from those regulating inflammation. In fact, some studies have suggested that ongoing inflammation is needed to reverse established and progressive fibrosis. The key cellular mediator of fibrosis is the myofibroblast, which when activated serves as the primary collagen-producing cell. Myofibroblasts are generated from a variety of sources including resident mesenchymal cells, epithelial and endothelial cells in processes termed epithelial/endothelial-mesenchymal (EMT/EndMT) transition, as well as from circulating fibroblast-like cells called fibrocytes that are derived from bone-marrow stem cells. Myofibroblasts are activated by a variety of mechanisms, including paracrine signals derived from lymphocytes and macrophages, autocrine factors secreted by myofibroblasts, and pathogen-associated molecular patterns (PAMPS) produced by pathogenic organisms that interact with pattern recognition receptors (i.e. TLRs) on fibroblasts. Cytokines (IL-13, IL-21, TGF-beta1), chemokines (MCP-1, MIP-1beta), angiogenic factors (VEGF), growth factors (PDGF), peroxisome proliferator-activated receptors (PPARs), acute phase proteins (SAP), caspases, and components of the renin-angiotensin-aldosterone system (ANG II) have been identified as important regulators of fibrosis and are being investigated as potential targets of antifibrotic drugs. This review explores our current understanding of the cellular and molecular mechanisms of fibrogenesis.
3,390 citations
Cites background from "Myofibroblasts and mechano-regulati..."
...TGFβ1, in turn, augments the production of interstitial collagens, fibronectin and proteoglycans by cardiac myofibroblasts [2]....
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TL;DR: Cancer-associated fibroblasts (CAFs) become synthetic machines that produce many different tumour components and have a role in creating extracellular matrix structure and metabolic and immune reprogramming of the tumour microenvironment with an impact on adaptive resistance to chemotherapy.
Abstract: Cancer is associated with fibroblasts at all stages of disease progression. This Review discusses the pleiotropic actions of cancer-associated fibroblasts (CAFs) on tumour cells and postulates that they are likely to be a heterogeneous and plastic population of cells in the tumour microenvironment. Among all cells, fibroblasts could be considered the cockroaches of the human body. They survive severe stress that is usually lethal to all other cells, and they are the only normal cell type that can be live-cultured from post-mortem and decaying tissue. Their resilient adaptation may reside in their intrinsic survival programmes and cellular plasticity. Cancer is associated with fibroblasts at all stages of disease progression, including metastasis, and they are a considerable component of the general host response to tissue damage caused by cancer cells. Cancer-associated fibroblasts (CAFs) become synthetic machines that produce many different tumour components. CAFs have a role in creating extracellular matrix (ECM) structure and metabolic and immune reprogramming of the tumour microenvironment with an impact on adaptive resistance to chemotherapy. The pleiotropic actions of CAFs on tumour cells are probably reflective of them being a heterogeneous and plastic population with context-dependent influence on cancer.
2,597 citations
References
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TL;DR: Details of how these signals control wound cell activities are beginning to emerge, and studies of healing in embryos have begun to show how the normal adult repair process might be readjusted to make it less like patching up and more like regeneration.
Abstract: The healing of an adult skin wound is a complex process requiring the collaborative efforts of many different tissues and cell lineages. The behavior of each of the contributing cell types during the phases of proliferation, migration, matrix synthesis, and contraction, as well as the growth factor and matrix signals present at a wound site, are now roughly understood. Details of how these signals control wound cell activities are beginning to emerge, and studies of healing in embryos have begun to show how the normal adult repair process might be readjusted to make it less like patching up and more like regeneration.
4,558 citations
"Myofibroblasts and mechano-regulati..." refers background in this paper
...33 ) and wound healing in the adult (for a review, see Ref...
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TL;DR: It is reported here that cdc42, another member of the rho family, triggers the formation of a third type of actin-based structure found at the cell periphery, filopodia, in addition to stress fibers, and rho controls the assembly of focal adhesion complexes.
4,440 citations
"Myofibroblasts and mechano-regulati..." refers background in this paper
...develop no, or only small (1 μm length), focal adhesion sites that are generally described as focal complexe...
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TL;DR: Inhibitory SMADs have been identified that block the activation of these pathway-restricted SMADS that direct transcription to effect the cell's response to TGF-β.
Abstract: The recent identification of the SMAD family of signal transducer proteins has unravelled the mechanisms by which transforming growth factor-beta (TGF-beta) signals from the cell membrane to the nucleus. Pathway-restricted SMADs are phosphorylated by specific cell-surface receptors that have serine/threonine kinase activity, then they oligomerize with the common mediator Smad4 and translocate to the nucleus where they direct transcription to effect the cell's response to TGF-beta. Inhibitory SMADs have been identified that block the activation of these pathway-restricted SMADs.
3,590 citations
TL;DR: The ability of cells to survey the mechanical properties of their surrounding environment is demonstrated and the possible involvement of both protein tyrosine phosphorylation and myosin-generated cortical forces in this process is suggested.
Abstract: Responses of cells to mechanical properties of the adhesion substrate were examined by culturing normal rat kidney epithelial and 3T3 fibroblastic cells on a collagen-coated polyacrylamide substrate that allows the flexibility to be varied while maintaining a constant chemical environment. Compared with cells on rigid substrates, those on flexible substrates showed reduced spreading and increased rates of motility or lamellipodial activity. Microinjection of fluorescent vinculin indicated that focal adhesions on flexible substrates were irregularly shaped and highly dynamic whereas those on firm substrates had a normal morphology and were much more stable. Cells on flexible substrates also contained a reduced amount of phosphotyrosine at adhesion sites. Treatment of these cells with phenylarsine oxide, a tyrosine phosphatase inhibitor, induced the formation of normal, stable focal adhesions similar to those on firm substrates. Conversely, treatment of cells on firm substrates with myosin inhibitors 2,3-butanedione monoxime or KT5926 caused the reduction of both vinculin and phosphotyrosine at adhesion sites. These results demonstrate the ability of cells to survey the mechanical properties of their surrounding environment and suggest the possible involvement of both protein tyrosine phosphorylation and myosin-generated cortical forces in this process. Such response to physical parameters likely represents an important mechanism of cellular interaction with the surrounding environment within a complex organism.
3,013 citations
3,010 citations