Tracheal regeneration using polycaprolactone/collagen-nanofiber coated with umbilical cord serum after partial resection

https://doi.org/10.1016/j.ijporl.2014.10.022Get rights and content

Abstract

Objectives

We developed a PCL/collagen nanofiber (PC-NF) scaffold/human umbilical cord serum (hUCS) to facilitate epithelial cell migration after implantation in order to promote regeneration of the tracheal epithelium without having a cell source.

Materials and Methods

The isolated chodrocytes from bovine auricle were used to evaluate the cellular activities cultured in the scaffolds with or without hUCS.

A 4 mm wide/8 mm long, full thickness anterior defect was created in the tracheal rings of rats. An anterior tracheal defect was implanted with a PCL/collagen-NF scaffold (PC-NF) in the control group (n = 7), and a PCL/collagen-NF coated with hUCS scaffold (PCU-NF) was implanted in the experimental group (n = 7). All rats were sacrificed at 7 weeks postoperatively. The cervical trachea, including the implant site, was resected, and gross and histological examinations were performed.

Results

The viable cells of PCU-NF scaffold were significantly higher than that of the PCL and PC-NF scaffold at 7 days; the result can be due to the exceptional biological growth factors of the hUCS. The steromicroscopic finding showed that the artificial trachea was covered by perichondrium without dislocation or granulation at 7 weeks postsurgery. When compared to the control group, the PCU-NF group showed a completely regenerated tracheal wall with luminal epilthelization.

Conclusion

As a results of this study, the PCU-NF scaffold promoted cartilage and epithelial regeneration over the artificial trachea without graft inflammation. Partial tracheal reconstruction using PCU-NF scaffold is suitable for enhancing cartilage and epithelial regeneration.

Introduction

Tracheal stenosis in childhood is a life-threatening problem. Defects of up to 50% of the tracheal length in adults and of up to 30% in infants may be reconstructed using a primary closure, but longer circumferential tracheal defects require more elaborate surgical reconstruction with grafts and/or flaps [1]. Despite many advances in material science, an optimal long-term tracheal replacement has yet to be developed.

Both bio-absorbable and non-absorbable materials have been used to design tracheal grafts [1], [2], [3], [4]. Bio-resorbable artificial trachea can reduce the foreign body reaction [2], [3], [4], and recently, researchers have reported the use of a tissue engineering approach for tracheal regeneration with a bio-resorbable collagen scaffold [5]. Polycaprolactone (PCL), polylactide, and polyglycoride have been used for artificial trachea [6], [7], [8], and cells (such as fibroblasts or stem cells) have been used together with bio-resorbable scaffolds [9], [10].

Electrospinning has recently emerged as one of the most successful techniques for fabricating scaffolds since it has an ability to generate fibers similar to fibrous structures of native extracelluar matrix. A scaffold based on electrospun nanofibers also has a large specific surface area that can be used to load bioactive molecules in order to facilitate efficient and selective cellular responses [11]. Previously, we had applied a PCL/collagen nanofiber (PC-NF) scaffold for bone regeneration [12]. A novel scaffold, the electrospun NF structure, has not been studied in the tracheal regeneration. In this study, PC-NF scaffold was produced by an electrospinning process, which is a nonwoven, three-dimensional, porous, and nano-scale fiber-based matrix. It is becoming increasingly clear that growth factors can work synergistically to enhance cartilage matrix synthesis [13].

To date only one growth factor, basic fibroblast growth factor (bFGF) has been used with collagen vitrigel sponge scaffold for tracheal regeneration [14]. Both autologous serum and umbilical cord serum owe their efficacy to the presence of various growth factors, like epidermal growth factor (EGF), acidic and basic fibroblast growth factor (FGF), platelet-derived growth factor, hepatocyte growth factor, vitamin A, transforming growth factor (TGF)-β, substance P, insulin-like growth factor (IGF)-1, nerve growth factor (NGF), fibronectin, and serum antiproteases, such as α2-macroglobulin [15]. The concentrations of EGF, TGF-β, and NGF are several times higher in umbilical cord serum (UCS) than peripheral blood serum [16].

Umbilical cord serum has many growth factors, and it has been used in studies for regenerative treatment in corneal epithelium or tympanic membrane study [17].

In this study, we used hUCS as a biomolecule combined with electrospun PC-NF scaffold. We hypothesized that PC-NF coated with hUCS scaffold (PCU-NF) would enhance the tracheal regeneration.

Section snippets

Fabrication of PC-NF (Fig. 1)

Poly(ɛ-caprolactone) (PCL, Mn = 60,000) was purchased from Sigma–Aldrich (St. Louis, MO), and type-I collagen from porcine tendon was obtained from Bioland Inc. (Matrixen-PSP; Bioland Inc., Cheonan City, South Korea). 10 wt% of PCL and solvent [4:1 ratio of n,n-dimethylformamide (DMF, JUNSEI) and methylene chloride (MC, JUNSEI)] were used.

As shown in Fig. 1, the cylindrical PC-NF scaffold was obtained using an electrospinning and dipping/drying process. The electrospinning setup consisted of a

In vitro cellular activities of chondrocyte on PCL, PC-NF, and PCU-NF mats

To evaluate in vitro cellular activities, the chondrocyte were cultured on electrospun PCL, PC-NF, and PCU-NF mat. The proliferation of viable cells of the scaffolds over various time periods (1, 3, and 7 days) was measured using the MTT assay. Fig. 4(a) shows the MTT results and, as the culture period increased, the optical density of the all scaffolds increased. But, the viable cells of PCU-NF scaffold were significantly higher than that of the PCL and PCL/collagen scaffold at 7 days; the

Discussion

In this study, we used a bio-resorbable PC-NF scaffold for tracheal reconstruction. The collagen scaffold has been used for patch repair of tracheal defects in a rat model [19], [20], and recently, PCL has been used for tracheal reconstruction [21], [22]. A medium-sized partial defect can be used during conventional surgery or off-the-shelf tracheal prosthesis. In recent work, PCL NF meshes have been found to be suitable for cartilage tissue engineering [23].

PCL degrades slowly in biological

Conclusion

As a result of this study, a PCU-NF scaffold for an artificial trachea was found to promote cartilage and epithelial regeneration without graft inflammation. Partial tracheal reconstruction using a PCU-NF scaffold is feasible for enhancing cartilage and epithelial regeneration.

Acknowledgements

This study was supported by Fishery of Food Agriculture, Forestry and Fisheries, Republic of Korea (grant no. A120942).

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