In vitro cell infiltration and in vivo cell infiltration and vascularization in a fibrous, highly porous poly(D,L‐lactide) scaffold fabricated by cryogenic electrospinning technique

Abstract

One of the obstacles limiting the application of electrospun scaffolds for tissue engineering is the nanoscale pores that inhibit cell infiltration. In this article, we describe a technique that uses ice crystals as templates to fabricate cryogenic electrospun scaffolds (CES) with large three-dimensional and interconnected pores using poly(D,L-lactide) (PLA). Manipulating the humidity of the electrospinning environment the pore sizes are controlled. We are able to achieve pore sizes ranging from 900 +/- 100 microm(2) to 5000 +/- 2000 microm(2) depending on the relative humidity used. Our results show that cells infiltrated the CES up to 50 microm in thickness in vitro under static culture conditions whereas cells did not infiltrate the conventional electrospun scaffolds. In vivo studies demonstrated improved cell infiltration and vascularization in the CES compared with conventionally prepared electrospun scaffolds. In gaining control of the pore characteristics, we can then design CES that are optimized for specific tissue engineering applications.

The effect of electrospun polycaprolactone scaffold morphology on human kidney epithelial cells

“…The diameter of the fibre determines the pore size of the scaffold, and this determines how well cells will penetrate into a scaffold (Balguid et al 2009;Baker et al 2008;Ju et al 2010). Techniques such as cryogenic electrospinning have shown to create structures with a much greater porosity, enabling cell infiltration throughout the scaffold (Leong et al 2013;Bulysheva et al 2013;Leong et al 2009); this can be controlled by modifying the humidity of the spinning environment, changing the amount of ice crystal formation on the cooled mandrel (Leong et al 2013). It is essential in the culture of a complex 3D system for a distribution of cells throughout the scaffold, increasing the porosity within electrospun scaffolds by cryogenic electrospinning allows for this greater cell distribution.…”

Influence of the fiber diameter and surface roughness of electrospun vascular grafts on blood activation

“…This technique is quite popular as it allows easy production of fibrous tubular scaffolds with controllable composition, architecture, fiber diameter and mechanical properties [12,15,16]. Scaffold properties tremendously affect the reaction of contacting cells and tissues; for instance, scaffold porosity affects the cell infiltration in vitro [15,16] and tissue integration in vivo [17] and fiber orientation can affect cell alignment [18]. Regarding vascular grafts, a number of studies showed that endothelialization on scaffolds with nano-fibers would be improved compared to micro-fiber scaffolds [12,19].…”

A review of electrospinning manipulation techniques to direct fiber deposition and maximize pore size

“…As the mandrel or solution is super cooled, crystals are formed and polymer solutions are electrospun around and throughout the crystals [145][146][147][148]. Once the scaffold is finished, the embedded crystals are removed by sublimation with a lyophilizer.…”

“…Once the scaffold is finished, the embedded crystals are removed by sublimation with a lyophilizer. This leaves void spaces in place of the crystals without damaging the surrounding fibers [145,146]. The pore size can be controlled by adjusting the relative humidity in the electrospinning chamber, allowing for increased flexibility in pore size [146].…”

“…This leaves void spaces in place of the crystals without damaging the surrounding fibers [145,146]. The pore size can be controlled by adjusting the relative humidity in the electrospinning chamber, allowing for increased flexibility in pore size [146]. Alternative techniques have been utilized to increase porosity in electrospun scaffolds, including the creation of macropores via laser cutting, and spinning of low density scaffolds [149,150].…”