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Journal ArticleDOI

Matrix elasticity directs stem cell lineage specification.

25 Aug 2006-Cell (Cell Press)-Vol. 126, Iss: 4, pp 677-689

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.

AbstractMicroenvironments appear important in stem cell lineage specification but can be difficult to adequately characterize or control with soft tissues. Naive mesenchymal stem cells (MSCs) are shown here to specify lineage and commit to phenotypes with extreme sensitivity to tissue-level elasticity. Soft matrices that mimic brain are neurogenic, stiffer matrices that mimic muscle are myogenic, and comparatively rigid matrices that mimic collagenous bone prove osteogenic. During the initial week in culture, reprogramming of these lineages is possible with addition of soluble induction factors, but after several weeks in culture, the cells commit to the lineage specified by matrix elasticity, consistent with the elasticity-insensitive commitment of differentiated cell types. Inhibition of nonmuscle myosin II blocks all elasticity-directed lineage specification-without strongly perturbing many other aspects of cell function and shape. The results have significant implications for understanding physical effects of the in vivo microenvironment and also for therapeutic uses of stem cells.

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Citations
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Journal ArticleDOI
09 Jun 2011-Nature
TL;DR: YAP/TAZ are identified as sensors and mediators of mechanical cues instructed by the cellular microenvironment and are functionally required for differentiation of mesenchymal stem cells induced by ECM stiffness and for survival of endothelial cells regulated by cell geometry.
Abstract: Cells perceive their microenvironment not only through soluble signals but also through physical and mechanical cues, such as extracellular matrix (ECM) stiffness or confined adhesiveness. By mechanotransduction systems, cells translate these stimuli into biochemical signals controlling multiple aspects of cell behaviour, including growth, differentiation and cancer malignant progression, but how rigidity mechanosensing is ultimately linked to activity of nuclear transcription factors remains poorly understood. Here we report the identification of the Yorkie-homologues YAP (Yes-associated protein) and TAZ (transcriptional coactivator with PDZ-binding motif, also known as WWTR1) as nuclear relays of mechanical signals exerted by ECM rigidity and cell shape. This regulation requires Rho GTPase activity and tension of the actomyosin cytoskeleton, but is independent of the Hippo/LATS cascade. Crucially, YAP/TAZ are functionally required for differentiation of mesenchymal stem cells induced by ECM stiffness and for survival of endothelial cells regulated by cell geometry; conversely, expression of activated YAP overrules physical constraints in dictating cell behaviour. These findings identify YAP/TAZ as sensors and mediators of mechanical cues instructed by the cellular microenvironment.

3,258 citations


Journal ArticleDOI
25 Nov 2009-Cell
TL;DR: Reduction of lysyl oxidase-mediated collagen crosslinking prevented MMTV-Neu-induced fibrosis, decreased focal adhesions and PI3K activity, impeded malignancy, and lowered tumor incidence, and data show how collagenCrosslinking can modulate tissue fibrosis and stiffness to force focal adhesion, growth factor signaling and breast malignancies.
Abstract: Tumors are characterized by extracellular matrix (ECM) remodeling and stiffening. The importance of ECM remodeling to cancer is appreciated; the relevance of stiffening is less clear. We found that breast tumorigenesis is accompanied by collagen crosslinking, ECM stiffening, and increased focal adhesions. Induction of collagen crosslinking stiffened the ECM, promoted focal adhesions, enhanced PI3 kinase (PI3K) activity, and induced the invasion of an oncogene-initiated epithelium. Inhibition of integrin signaling repressed the invasion of a premalignant epithelium into a stiffened, crosslinked ECM and forced integrin clustering promoted focal adhesions, enhanced PI3K signaling, and induced the invasion of a premalignant epithelium. Consistently, reduction of lysyl oxidase-mediated collagen crosslinking prevented MMTV-Neu-induced fibrosis, decreased focal adhesions and PI3K activity, impeded malignancy, and lowered tumor incidence. These data show how collagen crosslinking can modulate tissue fibrosis and stiffness to force focal adhesions, growth factor signaling and breast malignancy.

2,949 citations


Journal ArticleDOI
27 Nov 2009-Science
TL;DR: The extracellular matrix and ECM proteins are important in phenomena as diverse as developmental patterning, stem cell niches, cancer, and genetic diseases and these properties need to be incorporated into considerations of the functions of the ECM.
Abstract: The extracellular matrix (ECM) and ECM proteins are important in phenomena as diverse as developmental patterning, stem cell niches, cancer, and genetic diseases. The ECM has many effects beyond providing structural support. ECM proteins typically include multiple, independently folded domains whose sequences and arrangement are highly conserved. Some of these domains bind adhesion receptors such as integrins that mediate cell-matrix adhesion and also transduce signals into cells. However, ECM proteins also bind soluble growth factors and regulate their distribution, activation, and presentation to cells. As organized, solid-phase ligands, ECM proteins can integrate complex, multivalent signals to cells in a spatially patterned and regulated fashion. These properties need to be incorporated into considerations of the functions of the ECM.

2,486 citations


Journal ArticleDOI
26 Jun 2009-Science
TL;DR: Multifaceted technologies are increasingly required to produce and interrogate cells ex vivo, to build predictive models, and, ultimately, to enhance stem cell integration in vivo for therapeutic benefit.
Abstract: Stem cell fate is influenced by a number of factors and interactions that require robust control for safe and effective regeneration of functional tissue. Coordinated interactions with soluble factors, other cells, and extracellular matrices define a local biochemical and mechanical niche with complex and dynamic regulation that stem cells sense. Decellularized tissue matrices and synthetic polymer niches are being used in the clinic, and they are also beginning to clarify fundamental aspects of how stem cells contribute to homeostasis and repair, for example, at sites of fibrosis. Multifaceted technologies are increasingly required to produce and interrogate cells ex vivo, to build predictive models, and, ultimately, to enhance stem cell integration in vivo for therapeutic benefit.

2,271 citations


Journal ArticleDOI
TL;DR: The functional requirements, and types, of materials used in developing state of the art of scaffolds for tissue engineering applications are described and where future research and direction is required are described.
Abstract: Every day thousands of surgical procedures are performed to replace or repair tissue that has been damaged through disease or trauma. The developing field of tissue engineering (TE) aims to regenerate damaged tissues by combining cells from the body with highly porous scaffold biomaterials, which act as templates for tissue regeneration, to guide the growth of new tissue. This article describes the functional requirements, and types, of materials used in developing state of the art of scaffolds for tissue engineering applications. Furthermore, it describes the challenges and where future research and direction is required in this rapidly advancing field.

2,152 citations


References
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Journal ArticleDOI
02 Apr 1999-Science
TL;DR: Adult stem cells isolated from marrow aspirates of volunteer donors could be induced to differentiate exclusively into the adipocytic, chondrocytic, or osteocytic lineages.
Abstract: Human mesenchymal stem cells are thought to be multipotent cells, which are present in adult marrow, that can replicate as undifferentiated cells and that have the potential to differentiate to lineages of mesenchymal tissues, including bone, cartilage, fat, tendon, muscle, and marrow stroma. Cells that have the characteristics of human mesenchymal stem cells were isolated from marrow aspirates of volunteer donors. These cells displayed a stable phenotype and remained as a monolayer in vitro. These adult stem cells could be induced to differentiate exclusively into the adipocytic, chondrocytic, or osteocytic lineages. Individual stem cells were identified that, when expanded to colonies, retained their multilineage potential.

19,560 citations


"Matrix elasticity directs stem cell..." refers background or methods in this paper

  • ...…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...

    [...]

  • ...…specification of naive stem cells induced by soluble stimuli has been well described (Gang et al., 2004; Jaiswal et al., 1997; McBeath et al., 2004; Pittenger et al., 1999), but the results here report a strong and previously undocumented influence of microenvironment stiffness on stem cell…...

    [...]

  • ...The myoblast induction media used here (MIM, Table S2) is already known to promote myogenesis, with expression of MyoD, Myogenin, and skeletal muscle myosin heavy chain (Gang et al., 2004; Pittenger et al., 1999)....

    [...]

  • ...Naive mesenchymal stem cells (MSCs) are shown here to specify lineage and commit to phenotypes with extreme sensitivity to tissuelevel elasticity....

    [...]

  • ...…and have indeed been reported to differentiate into various anchorage-dependent cell types, including neurons, myoblasts, and osteoblasts (respectively, [Deng et al., 2005; Hofstetter et al., 2002; Kondo et al., 2005], [Pittenger et al., 1999], and [McBeath et al., 2004; Pittenger et al., 1999])....

    [...]


Journal ArticleDOI
18 Nov 2005-Science
TL;DR: An understanding of how tissue cells—including fibroblasts, myocytes, neurons, and other cell types—sense matrix stiffness is just emerging with quantitative studies of cells adhering to gels with which elasticity can be tuned to approximate that of tissues.
Abstract: Normal tissue cells are generally not viable when suspended in a fluid and are therefore said to be anchorage dependent. Such cells must adhere to a solid, but a solid can be as rigid as glass or softer than a baby's skin. The behavior of some cells on soft materials is characteristic of important phenotypes; for example, cell growth on soft agar gels is used to identify cancer cells. However, an understanding of how tissue cells-including fibroblasts, myocytes, neurons, and other cell types-sense matrix stiffness is just emerging with quantitative studies of cells adhering to gels (or to other cells) with which elasticity can be tuned to approximate that of tissues. Key roles in molecular pathways are played by adhesion complexes and the actinmyosin cytoskeleton, whose contractile forces are transmitted through transcellular structures. The feedback of local matrix stiffness on cell state likely has important implications for development, differentiation, disease, and regeneration.

5,408 citations


"Matrix elasticity directs stem cell..." refers background in this paper

  • ...Such a wide variation in matrix stiffness for differentiated cells is known to influence focal-adhesion structure and the cytoskeleton (Bershadsky et al., 2003; Cukierman et al., 2001; Discher et al., 2005; Engler et al., 2004a; Lo et al., 2000; Pelham and Wang, 1997)....

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Journal ArticleDOI
TL;DR: The first free, open-source system designed for flexible, high-throughput cell image analysis, CellProfiler is described, which can address a variety of biological questions quantitatively.
Abstract: Biologists can now prepare and image thousands of samples per day using automation, enabling chemical screens and functional genomics (for example, using RNA interference). Here we describe the first free, open-source system designed for flexible, high-throughput cell image analysis, CellProfiler. CellProfiler can address a variety of biological questions quantitatively, including standard assays (for example, cell count, size, per-cell protein levels) and complex morphological assays (for example, cell/organelle shape or subcellular patterns of DNA or protein staining).

3,916 citations


Journal ArticleDOI
TL;DR: It is demonstrated that cell shape regulates commitment of human mesenchymal stem cells to adipocyte or osteoblast fate and mechanical cues experienced in developmental and adult contexts, embodied by cell shape, cytoskeletal tension, and RhoA signaling, are integral to the commitment of stem cell fate.
Abstract: Commitment of stem cells to different lineages is regulated by many cues in the local tissue microenvironment. Here we demonstrate that cell shape regulates commitment of human mesenchymal stem cells (hMSCs) to adipocyte or osteoblast fate. hMSCs allowed to adhere, flatten, and spread underwent osteogenesis, while unspread, round cells became adipocytes. Cell shape regulated the switch in lineage commitment by modulating endogenous RhoA activity. Expressing dominant-negative RhoA committed hMSCs to become adipocytes, while constitutively active RhoA caused osteogenesis. However, the RhoA-mediated adipogenesis or osteogenesis was conditional on a round or spread shape, respectively, while constitutive activation of the RhoA effector, ROCK, induced osteogenesis independent of cell shape. This RhoA-ROCK commitment signal required actin-myosin-generated tension. These studies demonstrate that mechanical cues experienced in developmental and adult contexts, embodied by cell shape, cytoskeletal tension, and RhoA signaling, are integral to the commitment of stem cell fate.

3,724 citations


"Matrix elasticity directs stem cell..." refers background or result in this paper

  • ...Similar results as above are found with a standard osteoblast induction media (OIM), which is known to promote cytoskeletal rearrangement and alkaline phosphatase production (Jaiswal et al., 1997; McBeath et al., 2004)....

    [...]

  • ...Lineage specification of naive stem cells induced by soluble stimuli has been well described (Gang et al., 2004; Jaiswal et al., 1997; McBeath et al., 2004; Pittenger et al., 1999), but the results here report a strong and previously undocumented influence of microenvironment stiffness on stem cell…...

    [...]

  • ...(McBeath et al., 2004; Wang et al., 2002)....

    [...]

  • ...Myosins in MSCs Couple Expression to Matrix Stiffness and Reveal a Key Role for NMM IIs Forces generated and/or imposed on the cell’s actin cytoskeleton have been postulated to influence differentiation (Engler et al., 2004a; Hinz et al., 2001; McBeath et al., 2004), but no past reports have hinted at strong, tissuedirected feedback of microenvironment elasticity on myosin expression or stem cell lineage specification....

    [...]

  • ...Lineage specification of naive stem cells induced by soluble stimuli has been well described (Gang et al., 2004; Jaiswal et al., 1997; McBeath et al., 2004; Pittenger et al., 1999), but the results here report a strong and previously undocumented influence of microenvironment stiffness on stem cell specification....

    [...]


Journal ArticleDOI
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.

3,492 citations


"Matrix elasticity directs stem cell..." refers background in this paper

  • ...…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...

    [...]

  • ...…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…...

    [...]