Fiber-based tissue engineering: Progress, challenges, and opportunities

TLDR: This work critically review the techniques used to form cell-free and cell-laden fibers and to assemble them into scaffolds and compares their mechanical properties, morphological features and biological activity.

About: This article is published in Biotechnology Advances.The article was published on 2013-09-01 and is currently open access. It has received 379 citations till now.

Figures

Table 1 A selection of existing tissue engineering studies which used scaffolds formed by fiber-based techniques.

Fig. 7. Braided structure for tendon tissue engineering. (a) Braided silk scaffold; (b) SEM image of the A. pernyi silk scaffold; regenerated tendon after (c) 6, (d) 12, and (e)16 weeks post-surgery; (f) a normal tendon of a New Zealand white rabbit (Fang et al., 2009). Adapted with permission from Elsevier: [Material Science and Engineering C], copyright (2009).

Fig. 3. Programmable physicochemical coding of microfibers. (a) A microfluidic chip inspired by silk-spinning system of spiders. The chip consisted of six controllable inlets for different alginate based chemicals and one inlet for CaCl2 as the sheath fluid to generate a spinning process that mimics the spinning process of spiders. Pneumatic valves were used to modulate the composition of the fabricated fibers with millisecond response times. Fabricated fibers were collected by a motorized spool. (b) Parallel coding of alginate fibers; (c) grooved fibers fabricated using the microfluidic chip with grooved round channels. The number and size of the grooves were controlled by changing the flow rate and shape of the channels; (d) simultaneous delivery of hepatocytes and fibroblasts embedded in alginate followed by co-culture. Scale bares, 5 mm (a), 200 μm (b), 20 μm (c), and 100 μm (d) (Kang et al., 2011). Images are adapted with permission from Macmillan Publishers Ltd: [Nature Materials], copyright (2011).

Fig. 5. PGA woven scaffolds. (a) Microstructure of a 3D orthogonally woven structure. 3D structures were woven by interlocking multiple layers of two perpendicularly oriented sets of in-plane fibers with a third set of fibers in the through-plane direction; (b) SEM image from the top surface of the construct; (c) fluorescent image of a cell seeded construct illustrating uniform distribution of chondrocytes in fiber reinforced agarose (Moutos et al., 2007). Adapted with permission from Macmillan Publishers Ltd: [Nature Materials], copyright (2007).

Fig. 6. Knitted and embroidered structures used in tissue engineering. SEM photomicrograph PLGA knitted mesh after five days incubation (Chen et al., 2005). Adapted with permission f the embroidered PCL scaffold for bone tissue engineering; (e) a SEM image of non-coated PC cultivation (Rentsch et al., 2009). Adapted with permission from Springer: [Annals of Biom

Table 1 A selection of existing tissue engineering studies which used scaffolds formed by fiber-based techniques.

Frequently asked questions

Q1. What are the contributions mentioned in the paper "Fiber-based tissue engineering: progress, challenges, and opportunities" ?

A review of the top-down and bottom-up approaches for tissue engineering can be found in this paper. 

Q2. What are some other techniques that can be used for lab scale researches?

Other techniques, such as interfacial complexation and biospinning have also been used which can be used for lab scale researches. 

Q3. What are the characteristics of woven structures?

Regular woven structures have fibers in only two dimensions; exhibiting poor resistance towards forces applied in the through-plane direction. 

Q4. What is the way to engineer connective tissue?

Braiding offers the highest axial strength among the fiber based techniques which makes it the preferred method for engineering connective tissues. 

Q5. Why were cell-laden fibers made using alginate?

Cell-laden fibers were made using alginate because the prepolymer solution, the gelation agent and the coagulation bath are all compatible with live cells. 

Q6. What are the shortcomings of direct writing techniques?

Among the shortcomings of direct writing techniques are their slow fabrication rate and the fact that various stacked layers are not locked. 

Q7. What is the effect of adding gelatin on the cellular activity of the braided fabrics?

The addition of gelatin significantly reduced the mechanical strength of the scaffolds while crosslinking with EDC improved the cellular activity during a 21 day period. 

Q8. How did Mazzitelli et al. create a microfluidic chip?

Mazzitelli et al. fabricated a glass-based microfluidic chip consisted of three inlets and three dispersing chambers for coencapsulation of cells and drugs in fibers (Mazzitelli et al., 2011).673A. 

Q9. What is the effect of the spinning roller on the fiber diameter?

The rotation speed of the collecting rollermay also affect the fiber diameter as it imposes an external elongation stress on the fiber (Kang et al., 2011). 

Q10. What is the strength of the fibers fabricated with wetspinning?

Since the fibers fabricated with wetspinning are relatively thick, the pore size of the formed scaffolds is large (~250–500 μm) (Neves et al., 2011), and as they are deposited in a solution, the scaffolds tend to have a much higher porosity (up to 92%) (Pati et al., 2012), compared to those formed by dry electrospinning. 

Q11. What is the definition of tissue engineering?

In the past decades, tissue engineering has emerged as a multidisciplinary field encompassing medicine, biology, and engineering in which researchers utilize various tools to fabricate tissue-like biological constructs (Berthiaume et al., 2011). 

Q12. What are the uses of knitted structures in medicine?

As a result of their suitable mechanical properties and ease of fabrication, knitted fabrics have found several applications in medicine for example as surgical mesh in repairing hernia (Boukerrou et al., 2007; Jacobs et al., 1965), pelvic organ prolapse (Altman et al., 2008; Ganj et al., 2009), pelvic floor dysfunction (Ostergard, 2011), as well as endovascular prosthetic devices (Freitas et al., 2010). 

Q13. What are the major challenges facing the use of biospun fibers in FBTE?

The major challenges facing the use of biospun fibers in FBTE are: i) the limitation of resources, which make the scale-up process questionable; ii) the time consuming and expensive preprocessing and handling of natural silk fibers; iii) the lack of control over the size of the fabricated fibers; and iv) the current impossibility of incorporating cells in the fibers. 

Q14. What are the top-down methods for assembling tissue?

The assembling techniques for bottom-up fabrication include additive photo crosslinking of cellladen hydrogels (Liu and Bhatia, 2002; Tan and Desai, 2004), packing of cell encapsulated modules (Chan et al., 2010), directed assembly of modules (Zamanian et al., 2010), cell sheet methods (L'Heureux eta bcells scaffoldtissue constructtop-down approachFig. 

Q15. What are the advantages of planar braided structures?

Planar braided structures can be tailored in hierarchical organizations similar to the arrangement of natural tendons and ligaments. 

Q16. What are the main techniques used to form a biomimetic vasculature?

A variety of techniques have been explored to form biomimetic vasculature networks such as laser micromachining, soft lithography, electrostatic discharge, the use of hollow fibers, and sacrificial fibers (Huang et al., 2011; Takei et al., 2012). 

Q17. What is the use of meltspun fibers?

meltspun fibers are suitable for textile-based fabrication techniques such as knitting, weaving, or braiding (Ellä et al., 2011). 

Q18. How did Takei and his team form a microvascular network?

In a recent study, Takei et al. embedded sacrificial poly(methyl methacrylate) (PMMA) fibers in agarose gel and removed them chemically to form a microvascular network of microchannels (Takei et al., 2012).