Embryogenesis is directed by morphogens that induce differentiation within a defined tissue geometry. Tissue organization is mediated by cell-cell and cell-extracellular matrix (ECM) adhesions and is ...modulated by cell tension and tissue-level forces. Whether cell tension regulates development by modifying morphogen signaling is less clear. Human embryonic stem cells (hESCs) exhibit an intrinsic capacity for self-organization, which motivates their use as a tractable model of early human embryogenesis. We engineered patterned substrates that recapitulate the biophysical properties of the early embryo and mediate the self-organization of “gastrulation-like” nodes in cultured hESCs. Tissue geometries that generated local nodes of high cell-adhesion tension directed the spatial patterning of the BMP4-dependent “gastrulation-like” phenotype by enhancing phosphorylation and junctional release of β-catenin to promote Wnt signaling and mesoderm specification. Furthermore, direct force application via mechanical stretching promoted BMP-dependent mesoderm specification, confirming that tissue-level forces can directly regulate cell fate specification in early human development.
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•Substrates that recapitulate embryo elasticity promote hESC self-organization•“Gastrulation-like” morphogenesis occurs in regions of high cell-adhesion tension•Tissue geometry dictates the localization of high cell-adhesion tension•Tension releases junctional β-catenin and drives Wnt signaling to specify mesoderm
In this study, Muncie et al. engineered substrates that recapitulate the biophysical properties of the early embryo and facilitate a “gastrulation-like” morphogenesis of hESCs. They demonstrate that specific tissue geometries foster localized regions of high cell-adhesion tension that potentiate BMP4-dependent mesoderm specification by enhancing junctional release of β-catenin to promote Wnt signaling.
A growing body of work describes how physical forces in and around cells affect their growth, proliferation, migration, function and differentiation into specialized types. How cells receive and ...respond biochemically to mechanical signals is a process termed mechanotransduction. Disease may arise if a disruption occurs within this mechanism of sensing and interpreting mechanics. Cancer, cardiovascular diseases and developmental defects, such as during the process of neural tube formation, are linked to changes in cell and tissue mechanics. A breakdown in normal tissue and cellular forces activates mechanosignalling pathways that affect their function and can promote disease progression. The recent advent of high-resolution techniques enables quantitative measurements of mechanical properties of the cell and its extracellular matrix, providing insight into how mechanotransduction is regulated. In this review, we will address the standard methods and new technologies available to properly measure mechanical properties, highlighting the challenges and limitations of probing different length-scales. We will focus on the unique environment present throughout the development and maintenance of the central nervous system and discuss cases where disease, such as brain cancer, arises in response to changes in the mechanical properties of the microenvironment that disrupt homeostasis. This article is part of a discussion meeting issue 'Forces in cancer: interdisciplinary approaches in tumour mechanobiology'.
Hepatic stellate cells (HSCs) drive hepatic fibrosis. Therapies that inactivate HSCs have clinical potential as antifibrotic agents. We previously identified acid ceramidase (aCDase) as an ...antifibrotic target. We showed that tricyclic antidepressants (TCAs) reduce hepatic fibrosis by inhibiting aCDase and increasing the bioactive sphingolipid ceramide. We now demonstrate that targeting aCDase inhibits YAP/TAZ activity by potentiating its phosphorylation-mediated proteasomal degradation via the ubiquitin ligase adaptor protein β-TrCP. In mouse models of fibrosis, pharmacologic inhibition of aCDase or genetic knockout of aCDase in HSCs reduces fibrosis, stromal stiffness, and YAP/TAZ activity. In patients with advanced fibrosis, aCDase expression in HSCs is increased. Consistently, a signature of the genes most down-regulated by ceramide identifies patients with advanced fibrosis who could benefit from aCDase targeting. The findings implicate ceramide as a critical regulator of YAP/TAZ signaling and HSC activation and highlight aCDase as a therapeutic target for the treatment of fibrosis.
Organoid cultivation in suspension culture requires agitation at low shear stress to allow for nutrient diffusion, which preserves tissue structure. Multiplex systems for organoid cultivation have ...been proposed, but whether they meet similar shear stress parameters as the regularly used spinner flask and its correlation with the successful generation of brain organoids has not been determined.
Here we used computational fluid dynamics (CFD) to simulate two multiplex culture conditions: steering plates on an orbital shaker and the use of a previously described bioreactor. The bioreactor had low speed and high shear stress regions that may affect cell aggregate growth, depending on volume, whereas the computed variables of the steering plates were closer to those of the spinning flask.
Our protocol improves the initial steps of the standard brain organoid formation, and the produced organoids displayed regionalized brain structures, including retinal pigmented cells. Overall, we conclude that suspension culture on orbital steering plates is a cost-effective practical alternative to previously described platforms for the cultivation of brain organoids for research and multiplex testing.
A growing body of work describes how physical forces in and around cells affect their growth, proliferation, migration, function and differentiation into specialized types. How cells receive and ...respond biochemically to mechanical signals is a process termed mechanotransduction. Disease may arise if a disruption occurs within this mechanism of sensing and interpreting mechanics. Cancer, cardiovascular diseases and developmental defects, such as during the process of neural tube formation, are linked to changes in cell and tissue mechanics. A breakdown in normal tissue and cellular forces activates mechanosignalling pathways that affect their function and can promote disease progression. The recent advent of high-resolution techniques enables quantitative measurements of mechanical properties of the cell and its extracellular matrix, providing insight into how mechanotransduction is regulated. In this review, we will address the standard methods and new technologies available to properly measure mechanical properties, highlighting the challenges and limitations of probing different length-scales. We will focus on the unique environment present throughout the development and maintenance of the central nervous system and discuss cases where disease, such as brain cancer, arises in response to changes in the mechanical properties of the microenvironment that disrupt homeostasis.
This article is part of a discussion meeting issue 'Forces in cancer: interdisciplinary approaches in tumour mechanobiology'.
Regulation of drug prices that ensures adequate access to effective treatments and promotes innovation is a global challenge. In the United States, the government does not regulate drug prices when ...they come onto market. On the other hand, in countries such as France and Brazil, government agencies are responsible for setting up price limits by leveraging the interests of the companies and the countries’ population. In Brazil, safety and efficacy of drugs are regulated by the Brazilian Health Regulatory Agency, and drug prices are regulated by the Pharmaceutical Market Regulation Chamber with a participation of Brazilian Health Regulatory Agency. Here, we introduce the current challenges faced by the Brazilian government in the drug price regulation and present proposed initiatives aiming to streamline access to innovative treatments for its citizens.
Monoclonal antibodies are found in approximately 10% of patients with peripheral neuropathy (PN) of unknown etiology. Several autoantibodies, including anti-MAG (myelin-associated glycoprotein) ...antibodies, have been reported to induce neuropathy. It has been suggested that over 50% of patients with PN and IgM monoclonal gammopathy (MG) have anti-MAG IgM antibodies in their sera. This work aimed at studying the frequency and characteristics of PN in a group of Egyptian patients with MGs and to estimate the serum level of anti-MAG antibodies and its relationship to peripheral nerve dysfunction. Forty patients with MGs were enrolled in the study. Their mean age was 56.65 ± 8.55 years. There were 17 males and 23 females. Patients were subjected to complete general and neurological examination, laboratory investigations including serum LDH, β2 microglobulin, serum protein electrophoresis, urinary Bence-Jones protein, bone marrow aspiration and/or trephine biopsy, quantitative estimation of serum IgM and IgG by nephelometry, detection of anti-MAG antibodies by indirect immunofluorescence, radiological assessment and nerve conduction study of both upper and lower limbs. Clinical and electrophysiological evidences of PN were found in 32 (80%) out of the 40 patients with MG. Twenty-five patients (62.5%) had distal symmetrical polyneuropathy and seven (17.5%) had mononeuritis or mononeuritis multiplex. The majority of patients (65%) had sensory or predominantly sensorimotor polyneuropathy. The neuropathy was mainly demyelinating in 22 patients (55%) and axonal in the other 10 (25%) patients. Anti-MAG antibodies were positive in nine patients (22.5%) and six of them (66.6%) had PN. The latter was predominantly demyelinating motor neuropathy in 4 and axonal in the remaining 2. However, the relationship between the presence of anti-MAG antibodies and the development and type of PN was not statistically significant. Anti-MAG showed significant association with IgM level (
P
= 0.003**) and the MG subtypes: Waldenström’s macroglobulinemia (WM) and monoclonal gammopathy of undetermined significance (MGUS) (
P
= 0.004**). The present study showed high frequency (>60%) of distal symmetrical polyneuropathy in Egyptian patients with MG. The neuropathy was predominantly sensory and demyelinating. Anti-MAG antibodies were detected only in 22.5% of the patients, especially those with WM and MGUS and were associated with more motor and demyelinating neuropathy. We recommend that patients with chronic polyneuropathies should be evaluated for underlying plasma cell dyscrasia.
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