Electroporation of Cell-Seeded Electrospun Fiber Mats for Cryopreservation

We have recently reported on the high practical utility of using electroporation of clinically relevant cells with sugars for their xeno-free cryopreservation in suspension. This paper extends our earlier approach to in situ electroporating attached cells for their robust cryopreservation on artificial scaffolds. Using CAD modelling, a two-electrode setup has been designed and in-house constructed allowing for simultaneous electroporation in multi-well cell culture plates. Blend electrospinning process has been optimized in order to manufacture porous fibrous mats made of polycaprolactone (PCL, 100 mg/ml) and polylactide (PLA, 50 mg/ml) with an average thickness of 100 µm. Chinese hamster ovary (CHO) cells were grown and directly electroporated in nanofibrous blend electrospun fiber mats. An electric pulse was applied in the presence of propidium iodide and CellTracker Green to determine viable permeabilized cell counts using fluorescence microscopy. Cell recovery was evaluated using metabolic MTS assay 24 h post-electroporation. Electric field intensity and distribution within a 3D reconstructed fiber mat was simulated and visualized using COMSOL software. The results demonstrate that with developed setup it is feasible to electroporate around 80% of attached cells with 80% viability after electroporation when electric field strength was ≥1.7 kV/cm. COMSOL simulations showed local increases of electric field at intersection points of numerous fibers which may in part contribute to the observed drop in cell viability post-electroporation. Future studies anticipate implementation of the developed approach in effective biopreservation of stem cells on electrospun fiber mats as a model of tissue-engineered constructs.