A quantitative analysis of cell bridging kinetics on a scaffold using computer vision algorithms

Lanaro, Matthew; Mclaughlin, Maximilion P.; Simpson, Matthew J.; Buenzli, Pascal R.; Wong, Cynthia S.; Allenby, Mark C.; Woodruff, Maria A.

doi:10.1016/j.actbio.2021.09.042

“…The obtained fiber diameters results were in good agreement with our previous work [28]; however, the PCL-A group's pore size was smaller than ours [28]. This may be caused by technical variations during different manufacturing batches, while our PCL-R and PCL-A had similar pore sizes (~200 µm) since scaffold pore size is one of the critical factors directing adhesion and differentiation [38,39]. Additionally, mechanical testing demonstrated that the randomly organized membranes were softer than the aligned fibers with a respective tensile modulus of 32.5 ± 0.4 kPa and 56.7 ± 22.5 kPa, respectively.…”

Section: Focal Adhesions Are Altered On Aligned Fibers On a Pcl Porous Scaffoldsupporting

confidence: 89%

The Mechanosensing and Global DNA Methylation of Human Osteoblasts on MEW Fibers

Han

¹

,

Vaquette

²

,

Abdal‐hay

³

et al. 2021

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Cells interact with 3D fibrous platform topography via a nano-scaled focal adhesion complex, and more research is required on how osteoblasts sense and respond to random and aligned fibers through nano-sized focal adhesions and their downstream events. The present study assessed human primary osteoblast cells’ sensing and response to random and aligned medical-grade polycaprolactone (PCL) fibrous 3D scaffolds fabricated via the melt electrowriting (MEW) technique. Cells cultured on a tissue culture plate (TCP) were used as 2D controls. Compared to 2D TCP, 3D MEW fibrous substrates led to immature vinculin focal adhesion formation and significantly reduced nuclear localization of the mechanosensor-yes-associated protein (YAP). Notably, aligned MEW fibers induced elongated cell and nucleus shape and highly activated global DNA methylation of 5-methylcytosine, 5-hydroxymethylcytosine, and N-6 methylated deoxyadenosine compared to the random fibers. Furthermore, although osteogenic markers (osterix-OSX and bone sialoprotein-BSP) were significantly enhanced in PCL-R and PCL-A groups at seven days post-osteogenic differentiation, calcium deposits on all seeded samples did not show a difference after normalizing for DNA content after three weeks of osteogenic induction. Overall, our study linked 3D extracellular fiber alignment to nano-focal adhesion complex, nuclear mechanosensing, DNA epigenetics at an early point (24 h), and longer-term changes in osteoblast osteogenic differentiation.

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“…The coupling between the spatial and temporal distribution of the tissue and the underlying substrate is similar to that observed in the experiments (Lanaro et al. 2021 ). Given this experimental motivation we will now set about analysing the mathematical model to provide insight into how the substrate dynamics affect the speed of invasion.…”

Section: Resultssupporting

confidence: 83%

“…This feature leads to predictions of tissue formation involving the propagation of well-defined sharp fronts, and two-dimensional numerical simulations of the mathematical model recapitulate key features of recent experiments that involved the formation of thin tissues grown on 3D-printed scaffolds (Lanaro et al. 2021 ). To gain a deeper understanding of how the rate of substrate production and decay affects the rate of tissue production, the focus of this work is to study solutions of the substrate model in a one-dimensional geometry.…”

Section: Discussionsupporting

confidence: 69%

“…In vitro tissues grown on 3D scaffolds are more reproducible and more biologically realistic than tissues grown in traditional two-dimensional tissue culture (Lanaro et al. 2021 ). The experimental images in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Closer inspection of these experimental images shows that cells not only migrate and proliferate during the pore bridging process, but they also produce an extracellular medium that is laid down onto the surface of the pore (Lanaro et al. 2021 ).

Fig.…”

Section: Introductionmentioning

confidence: 99%

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El‐Hachem

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McCue

²

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Simpson

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We consider a continuum mathematical model of biological tissue formation inspired by recent experiments describing thin tissue growth in 3D-printed bioscaffolds. The continuum model, which we call the substrate model, involves a partial differential equation describing the density of tissue, $${\hat{u}}(\hat{{\mathbf {x}}},{\hat{t}})$$ u ^ ( x ^ , t ^ ) that is coupled to the concentration of an immobile extracellular substrate, $${\hat{s}}(\hat{{\mathbf {x}}},{\hat{t}})$$ s ^ ( x ^ , t ^ ) . Cell migration is modelled with a nonlinear diffusion term, where the diffusive flux is proportional to $${\hat{s}}$$ s ^ , while a logistic growth term models cell proliferation. The extracellular substrate $${\hat{s}}$$ s ^ is produced by cells and undergoes linear decay. Preliminary numerical simulations show that this mathematical model is able to recapitulate key features of recent tissue growth experiments, including the formation of sharp fronts. To provide a deeper understanding of the model we analyse travelling wave solutions of the substrate model, showing that the model supports both sharp-fronted travelling wave solutions that move with a minimum wave speed, $$c = c_{\mathrm{min}}$$ c = c min , as well as smooth-fronted travelling wave solutions that move with a faster travelling wave speed, $$c > c_{\mathrm{min}}$$ c > c min . We provide a geometric interpretation that explains the difference between smooth and sharp-fronted travelling wave solutions that is based on a slow manifold reduction of the desingularised three-dimensional phase space. In addition, we also develop and test a series of useful approximations that describe the shape of the travelling wave solutions in various limits. These approximations apply to both the sharp-fronted and smooth-fronted travelling wave solutions. Software to implement all calculations is available at GitHub.

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Materials Design Innovations in Optimizing Cellular Behavior on Melt Electrowritten (MEW) Scaffolds

Devlin,

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Adv Funct Materials

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The field of melt electrowriting (MEW) has seen significant progress, bringing innovative advancements to the fabrication of biomaterial scaffolds, and creating new possibilities for applications in tissue engineering and beyond. Multidisciplinary collaboration across materials science, computational modeling, AI, bioprinting, microfluidics, and dynamic culture systems offers promising new opportunities to gain deeper insights into complex biological systems. As the focus shifts towards personalized medicine and reduced reliance on animal models, the multidisciplinary approach becomes indispensable. This review provides a concise overview of current strategies and innovations in controlling and optimizing cellular responses to MEW scaffolds, highlighting the potential of scaffold material, MEW architecture, and computational modeling tools to accelerate the development of efficient biomimetic systems. Innovations in material science and the incorporation of biologics into MEW scaffolds have shown great potential in adding biomimetic complexity to engineered biological systems. These techniques pave the way for exciting possibilities for tissue modeling and regeneration, personalized drug screening, and cell therapies.

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A quantitative analysis of cell bridging kinetics on a scaffold using computer vision algorithms

Cited by 12 publications

References 71 publications

The Mechanosensing and Global DNA Methylation of Human Osteoblasts on MEW Fibers

The Mechanosensing and Global DNA Methylation of Human Osteoblasts on MEW Fibers

A Continuum Mathematical Model of Substrate-Mediated Tissue Growth

Materials Design Innovations in Optimizing Cellular Behavior on Melt Electrowritten (MEW) Scaffolds

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