Bioreactors Perfusion Vascular Custom

Scaffold permeability measurements experimental results

The permeability of a biomaterial is closely related to the suitability of such material to be used for Tissue Engineering scaffold manufacturing, specially in the case of three dimensional scaffolds where the adequate nutrient supply to cells located in the inner part of the scaffold is crucial. In these cases, a sufficiently high permeability value is necessary to assure the sufficient nutrient supply to those cells.

Thus, determining the permeability of a biomaterial or a porous scaffold is crucial in order to evaluate its feasibility to host viable cell populations. Likewise, measuring the permeability of a scaffold while cells are being cultured on it can be also used to evaluate the cell proliferation rate, since extracellular matrix generated by cells modify the scaffold micro-structure and, therefore, its permeability. Thus, permeability variations may be used as an indirect measurement of cellular activity.

As it is presented below, EBERS TEB1000 Master Unit in combination with EBERS perfusion package can be easily used to measure the permeability of a particular scaffold, both of an non-seeded scaffold and in a long-term culture.

Materials and methods

The EBERS Master Unit and the perfusion package can be straightforwardly used to measure the permeability of a scaffold under deformation states. Such purpose, can be obtained just by controlling the pressure drop between the input and output ports of the perfusion package chamber.

The materials necessary for this experiments are:

  • Bioreactor: EBERS TEB1000 Master Unit + EBERS perfusion package.

  • Scaffolds: PLLA-agarose cylinder-shaped scaffolds of dimensions 5 x 6 (diameter x height).

  • Pressure sensor: to measure the pressure drop in the perfusion package chamber.

  • Holding disks: different thickness holding disks were used to apply compressive deformation to the scaffolds.

  • Deformation levels: compressive deformations of 10, 20 and 40 percent where applied to the studied scaffolds.

Experimental set-up

Bioreactor experimental set-up for permeability measurement under deformation loads

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Results

Pressure drop vs. flow rate

The obtained results showed the strong influence of deformation on the pressure drop caused by the scaffold.

Figure below represents the relationship between flow rate and pressure drop under deformation levels of 10%, 20% and 40%.

Pressure drop vs. flow rate

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Permeability vs. deformation

Closely related to the pressure drop, the scaffold permeability can be calculated by means of simple mathematical expressions. Figure beside represents the permeability values calculated from the experimental measures in [m-2] for different compression values.

Furthermore, it is observed that the variability in the measured values is small, which confirms the validity of the obtained results.

Permeability vs. deformation

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