Tunneling Nanotubes between Cells Migrating in ECM Mimicking Fibrous Environments

Our plain-English summary of Tunneling Nanotubes between Cells Migrating in ECM Mimicking Fibrous Environments, by A. Jana, K. Ladner, E. Lou, et al (Cancers, 2022).

The study

• Authors: A. Jana, K. Ladner, E. Lou, A.S. Nain
• Journal: Cancers
• Published: 2022;14(8)
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Tunneling nanotubes (TNTs) comprise a unique class of actin-rich nanoscale membranous protrusions. They enable long-distance intercellular communication and may play an integral role in tumor formation, progression, and drug resistance. TNTs are three-dimensional, but nearly all studies have investigated them using two-dimensional cell culture models. Here, we applied a unique 3D culture platform consisting of crosshatched and aligned fibers to fabricate synthetic suspended scaffolds that mimic the native fibrillar architecture of tumoral extracellular matrix (ECM) to characterize TNT formation and function in its native state. TNTs are upregulated in malignant mesothelioma; we used this model to analyze the biophysical properties of TNTs in this 3D setting, including cell migration in relation to TNT dynamics, rate of TNT-mediated intercellular transport of cargo, and conformation of TNT-forming cells. We found that highly migratory elongated cells on aligned fibers formed significantly longer but fewer TNTs than uniformly spread cells on crossing fibers. We developed new quantitative metrics for the classification of TNT morphologies based on shape and cytoskeletal content using confocal microscopy. In sum, our strategy for culturing cells in ECM-mimicking bioengineered scaffolds provides a new approach for accurate biophysical and biologic assessment of TNT formation and structure in native fibrous microenvironments.

In plain English

This was a laboratory study of cancer cells, not of people, and it did not involve asbestos. The authors grew MSTO-211H cells, a cell line derived from a patient with malignant pleural mesothelioma. Some cells grew on suspended scaffolds of polystyrene nanofibers laid out in a crosshatch or an aligned pattern, meant to mimic the fibrous tissue around tumors. Others grew on flat surfaces for comparison. The authors studied tunneling nanotubes, thin tubes that connect cells and carry cargo between them. On aligned fibers, cells moved faster and fewer cells were connected by nanotubes. The nanotubes there were longer, averaging 40.3 micrometers, compared with 19.4 on crosshatch fibers and 17.3 on flat surfaces. On aligned fibers, about 85% of the nanotubes examined were near the cell ends. A drug that reduces cell movement, Y27632, increased nanotube formation on all surfaces. Nanotubes on scaffolds touched the fibers, and cargo slowed where nanotubes met fibers. Thicker nanotubes more often contained microtubules and vimentin. The authors concluded that a cell's surroundings and its movement pattern influence nanotube formation.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory (in vitro) cell culture experiment comparing cells grown on suspended nanofiber scaffolds of two geometries with cells on flat 2D surfaces
• Who was studied: MSTO-211H cells, a commercially purchased cell line derived from a human patient with malignant pleural mesothelioma; no human participants
• Exposure: No asbestos exposure was studied. Cells were grown on suspended polystyrene nanofiber scaffolds: crosshatch networks of about 500 nm fibers spaced about 18 micrometers apart, and aligned networks. These were compared with flat 2D surfaces. Some cells were also treated with the ROCK inhibitor Y27632.
• Main results:
  • Cells on aligned networks showed a significantly reduced proportion of nanotube-connected cells. Cells on crosshatch networks showed levels similar to cells on flat 2D surfaces.
  • Average nanotube length (mean plus or minus SEM) was 40.3 plus or minus 4.2 micrometers on aligned networks, 19.4 plus or minus 2.5 micrometers on crosshatch networks, and 17.3 plus or minus 1 micrometers on flat 2D (p less than 0.0001). These figures are based on 129, 88 and 247 nanotubes respectively.
  • Cells migrated faster on aligned networks, which led to more stretching of nanotubes, frequent breakage, and a lower nanotube index on aligned fibers.
  • About 85% of nanotubes were located towards the cell ends. The figure legend gives this as percent occurrence for aligned fiber networks, n = 15 nanotubes.
  • Treatment with Y27632 significantly increased nanotube formation compared with controls on all substrates, with almost a two-fold increase on aligned scaffolds.
  • On suspended fiber networks, nanotubes regularly made physical contact with the fibers. This was rarely seen on flat surfaces.
  • Microtubules and vimentin intermediate filaments were present significantly more often in thick nanotubes than in thin ones.
  • Average cargo ('gondola') velocity was significantly higher in nanotubes on crosshatch scaffolds than on flat 2D or aligned scaffolds. Sample sizes were 38 on crosshatch, 13 on flat 2D and 6 on aligned.
• The authors' conclusion: The authors concluded that their findings suggest a cell's microenvironment and its migration pattern influence nanotube formation.
• Limitations the authors state:
  • The authors stated that the apparent link between cargo velocity and nanotube thickness, length and cytoskeletal composition needs further analysis.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelioma.

Related studies

• Treatment with tumor-treating fields (TTFields) suppresses intercellular tunneling nanotube formation in vitro and upregulates immuno-oncologic biomarkers in vivo in malignant mesothelioma — A. Sarkari, S. Korenfeld, et al. (2023)
• Tunneling nanotubes provide a unique conduit for intercellular transfer of cellular contents in human malignant pleural mesothelioma — E. Lou, S. Fujisawa, et al. (2012)
• Tunneling Nanotubes: A new paradigm for studying intercellular communication and therapeutics in cancer — E. Lou, S. Fujisawa, et al. (2012)
• Intercellular communication in malignant pleural mesothelioma: properties of tunneling nanotubes — J.W. Ady, S. Desir, et al. (2014)
• Tunneling nanotubes: an alternate route for propagation of the bystander effect following oncolytic viral infection — J. Ady, V. Thayanithy, et al. (2016)
• Cytotoxicity assessment of some carbon nanotubes and related carbon nanoparticle aggregates and the implications for anthropogenic carbon nanotube aggregates in the environment — L.E. Murr, K.M. Garza, et al. (2005)

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