A Non-woven Path: Electrospun Poly(lactic acid) Scaffolds for Kidney Tissue Engineering

Abstract

Chronic kidney disease is a major global health problem affecting millions of people; kidney tissue engineering provides an opportunity to better understand this disease, and has the capacity to provide a cure. Two-dimensional cell culture and decellularised tissue have been the main focus of this research thus far, but despite promising results these methods are not without their shortcomings. Polymer fabrication techniques such as electrospinning have the potential to provide a non-woven path for kidney tissue engineering. In this experiment we isolated rat primary kidney cells which were seeded on electrospun poly(lactic acid) scaffolds. Our results showed that the scaffolds were capable of sustaining a multi-population of kidney cells, determined by the presence of: aquaporin-1 (proximal tubules), aquaporin-2 (collecting ducts), synaptopodin (glomerular epithelia) and von Willebrand factor (glomerular endothelia cells), viability of cells appeared to be unaffected by fibre diameter. The ability of electrospun polymer scaffold to act as a conveyor for kidney cells makes them an ideal candidate within kidney tissue engineering; the non-woven path provides benefits over decellularised tissue by offering a high morphological control as well as providing superior mechanical properties with degradation over a tuneable time frame.

Keywords: Electrospinning; Kidney tissue engineering; Primary cells; Renal; Scaffold architecture.

Fig. 1

A diagram of the kidney showing the structure of kidney including the nephron and glomerulus, highlighting the location of key cell types, representative IHC images are taken from large scaffold at 7 days, scale bar is 100 µm

Fig. 2

Scaffolds were fabricated by electrospinning, where a high voltage is applied to a polymer solution, forming a Taylor cone, this is then accelerated towards a ground source. Fibre architecture was determined by spinning parameters; A cryogenic fibres, using ice crystal formation as a template for fibre deposition and B random fibres onto a slowly rotating mandrel. SEM images below demonstrate the difference in fibre diameter of the scaffolds, which were spun using the same solvent and polymer but different electrospinning parameters and percentage weight solutions

Fig. 3

Cell number estimated from a standard curve, analysed using a CellTitre blue^® fluorescence assay. This demonstrates the ability of all scaffold architectures to support primary kidney cell life. No significant differences found in analysis using a one-way ANOVA F(7,24) = 2.05, p = 0.090. Data presented as mean ± 95% confidence intervals, circles show individual data points

Fig. 4

DNA quantity per scaffold at 3 and 7 days, assessed by PicoGreen assay. This confirms the ability of all scaffold architectures to support primary kidney cell life. Analysis using a one-way ANOVA showed significant differences F(7,23) = 4.79, p = 0.002, post hoc Tukey analysis shows that was in regards to cryogenic scaffolds. Data presented as mean ± 95% confidence intervals, circles denote individual data points

Fig. 5

Fluorescence images showing DAPI and IHC, used to show the presence of key functional marker of several cell types: A–D aquaporin-2, aquaporin-1 indicate the presence of tubular cells, von Willebrand factor indicates glomerular endothelial cells and synaptopodin indicated the glomerular epithelia, scale bar is 100 μm