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Microscale diffusion measurements and simulation of a scaffold with a permeable strut.

Lee SY, Lee BR, Lee J, Kim S, Kim JK, Jeong YH, Jin S - Int J Mol Sci (2013)

Bottom Line: No significant differences were detected between DWES line patterns fabricated with polymer supplied at flow rates of 0.1 and 0.5 mL/h.The permeable strut scaffolds exhibited enhanced cell growth.Saturated depths at which cells could grow to confluence were 15% deeper for the permeable strut scaffolds than for the non-permeable strut scaffold.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical System Engineering, Graduate School of Knowledge-Based Technology and Energy, Korea Polytechnic University, Jeongwang-dong, Siheung-si, Gyeonggi-do 429-793, Korea. songwan@kpu.ac.kr.

ABSTRACT
Electrospun nanofibrous structures provide good performance to scaffolds in tissue engineering. We measured the local diffusion coefficients of 3-kDa FITC-dextran in line patterns of electrospun nanofibrous structures fabricated by the direct-write electrospinning (DWES) technique using the fluorescence recovery after photobleaching (FRAP) method. No significant differences were detected between DWES line patterns fabricated with polymer supplied at flow rates of 0.1 and 0.5 mL/h. The oxygen diffusion coefficients of samples were estimated to be ~92%-94% of the oxygen diffusion coefficient in water based on the measured diffusion coefficient of 3-kDa FITC-dextran. We also simulated cell growth and distribution within spatially patterned scaffolds with struts consisting of either oxygen-permeable or non-permeable material. The permeable strut scaffolds exhibited enhanced cell growth. Saturated depths at which cells could grow to confluence were 15% deeper for the permeable strut scaffolds than for the non-permeable strut scaffold.

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Schematic representation of the simulation domain. (a) Lattice model; (b) Staggered model.
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f8-ijms-14-20157: Schematic representation of the simulation domain. (a) Lattice model; (b) Staggered model.

Mentions: The simulation was performed using the hypothetical 3D scaffold model shown in Figure 8. The “scaffold strut domain” in Figure 8 simulates the strut of a scaffold with an oxygen diffusion coefficient, Ds. The “cell culture domain”, simulates the space between the struts; cells are assumed to be cultured only in this domain. The height of each strut was set to 50 μm; therefore, the height of each layer of the scaffold was 50 μm. The mesh pattern was created by rotating each layer 90° and stacking layers on top of each other. The total thickness was set to 1000 μm. The diffusion coefficient of the cell culture domain was assumed to be the oxygen diffusion coefficient in typical tissue culture system (Dt) [28]. The diffusion coefficient of the scaffold strut domain Ds was altered from 0 to 2.68 × 10−5 cm2/s; that is, the diffusion coefficient of oxygen in water (Dw) [37]. The initial oxygen concentration within the scaffold model was assumed to be the maximum dissolved oxygen concentration (C0) [28], and the bottom of the scaffold model was assumed to be a wall. The top surface of the scaffold model was assumed to be exposed to fresh media; therefore, the oxygen concentration of the top surface was maintained. Other boundaries were assumed to be symmetrical so that conditions were similar to the culture conditions of a flat, board-shaped scaffold. Oxygen consumption in the cell culture domains was established using the Michaelis-Menten equation (Equation (3)): [42].


Microscale diffusion measurements and simulation of a scaffold with a permeable strut.

Lee SY, Lee BR, Lee J, Kim S, Kim JK, Jeong YH, Jin S - Int J Mol Sci (2013)

Schematic representation of the simulation domain. (a) Lattice model; (b) Staggered model.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3821608&req=5

f8-ijms-14-20157: Schematic representation of the simulation domain. (a) Lattice model; (b) Staggered model.
Mentions: The simulation was performed using the hypothetical 3D scaffold model shown in Figure 8. The “scaffold strut domain” in Figure 8 simulates the strut of a scaffold with an oxygen diffusion coefficient, Ds. The “cell culture domain”, simulates the space between the struts; cells are assumed to be cultured only in this domain. The height of each strut was set to 50 μm; therefore, the height of each layer of the scaffold was 50 μm. The mesh pattern was created by rotating each layer 90° and stacking layers on top of each other. The total thickness was set to 1000 μm. The diffusion coefficient of the cell culture domain was assumed to be the oxygen diffusion coefficient in typical tissue culture system (Dt) [28]. The diffusion coefficient of the scaffold strut domain Ds was altered from 0 to 2.68 × 10−5 cm2/s; that is, the diffusion coefficient of oxygen in water (Dw) [37]. The initial oxygen concentration within the scaffold model was assumed to be the maximum dissolved oxygen concentration (C0) [28], and the bottom of the scaffold model was assumed to be a wall. The top surface of the scaffold model was assumed to be exposed to fresh media; therefore, the oxygen concentration of the top surface was maintained. Other boundaries were assumed to be symmetrical so that conditions were similar to the culture conditions of a flat, board-shaped scaffold. Oxygen consumption in the cell culture domains was established using the Michaelis-Menten equation (Equation (3)): [42].

Bottom Line: No significant differences were detected between DWES line patterns fabricated with polymer supplied at flow rates of 0.1 and 0.5 mL/h.The permeable strut scaffolds exhibited enhanced cell growth.Saturated depths at which cells could grow to confluence were 15% deeper for the permeable strut scaffolds than for the non-permeable strut scaffold.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical System Engineering, Graduate School of Knowledge-Based Technology and Energy, Korea Polytechnic University, Jeongwang-dong, Siheung-si, Gyeonggi-do 429-793, Korea. songwan@kpu.ac.kr.

ABSTRACT
Electrospun nanofibrous structures provide good performance to scaffolds in tissue engineering. We measured the local diffusion coefficients of 3-kDa FITC-dextran in line patterns of electrospun nanofibrous structures fabricated by the direct-write electrospinning (DWES) technique using the fluorescence recovery after photobleaching (FRAP) method. No significant differences were detected between DWES line patterns fabricated with polymer supplied at flow rates of 0.1 and 0.5 mL/h. The oxygen diffusion coefficients of samples were estimated to be ~92%-94% of the oxygen diffusion coefficient in water based on the measured diffusion coefficient of 3-kDa FITC-dextran. We also simulated cell growth and distribution within spatially patterned scaffolds with struts consisting of either oxygen-permeable or non-permeable material. The permeable strut scaffolds exhibited enhanced cell growth. Saturated depths at which cells could grow to confluence were 15% deeper for the permeable strut scaffolds than for the non-permeable strut scaffold.

Show MeSH