A multilevel numerical model quantifying cell deformation in encapsulated alginate structures

Abstract

Mechanical forces not only deform cells, but also alter their functions due to biological responses. While current biomanufacturing processes are capable of producing tissue scaffolds with cells encapsulated, it is essential to understand cell responses to process-induced mechanical disturbances. In this study the stresses and deformations of encapsulated cells under compressive loads are quantified via a multilevel nonlinear finite element approach. The macrolevel model is used to mechanically characterize the alginate-cell construct. At the microlevel, the effects of alginate concentration, cell model, and the microlevel geometric heterogeneity on cell deformation are examined. Cells are modeled as single phase inclusions containing only a nucleus phase; then as a two-phase inclusion comprised of a nucleus phase and cytoplasm phase. This study also analyzes the effects of two geometrical parameters-namely, cell size and cell distribution-on the local stress levels of the cell. Subsequent statistical analyses provide insight into the degree of influence of these factors. The study shows that cells embedded in a higher alginate concentration, 3% w/v, experience higher stress levels as compared to cells embedded in a lower alginate concentration, 1.5% w/v. Furthermore, analysis of the geometric heterogeneity indicates that there is a much higher stress concentration in areas where cells are clustered together as compared to areas where cells are relatively isolated.

Bioprinting Technology: A Current State-of-the-Art Review

“…Flowever, screw-driven extrusion can generate larger pressure drops along the nozzle, which can potentially be harmful for loaded cells. Their rheology study and cell viability assay were per formed to investigate cell damage due to mechanical stress during the printing process [83], They found that cell viability was influ enced by material concentration, dispensing pressure, material flow rate and nozzle geometry. The main advant age of using a pneumatically driven system is the various types and viscosities of bioinks that can be dispensed by adjusting the pressure and valve gating time.…”

Three dimensional multi-scale modelling and analysis of cell damage in cell-encapsulated alginate constructs

“…12 compares the distributions of the maximum strain from uniform material property and random material property analyses; the differences are 2 and 25% for the mean value and standard deviation, respectively. Furthermore, in our previous study (Nair et al, 2007), the cell diameter was randomly varied from 20 to 40 mm, and the resulting changes in stresses and strains were observed as 1% of the mean value and 5% of the standard deviation. Finally, micrographic images of tissue constructs suggest that the encapsulated endothelial cells tend to be spherical (Fig.…”

“…It is noted that the SED of cell is close to the mean value obtained from the multi-cellular analyses. The results from the 3D analyses were also compared with those from our previous 2D analyses (Nair et al, 2007). Fig.…”

Recent cell printing systems for tissue engineering

“…Cell-embedded 3D printing with microextrusion includes a d ispensing system that uses pneumatic or mechanical forces to extrude bioink in a line ( ) [29][30][31][32][33] . It is one of the most common cell printing methods owing to its accessibility and versatility in printing 3D structures.…”