Gentle cyclic straining of human fibroblasts on electrospun scaffolds enhances their regenerative potential.

The extracellular matrix of fascia-like tissues is a resilient network of collagenous fibers that withstand the forces of daily life. When overstretched, the matrix may tear, with serious consequences like pelvic organ prolapse (POP). Synthetic implants can provide mechanical support and evoke a host response that induces new matrix production, thus reinforcing the fascia. However, there is considerable risk of scar formation and tissue contraction which result in severe complications. Matrix producing fibroblasts are both mechanosensitive and contractile; their behavior depends on the implant's surface texture and mechanical straining. Here we investigate the effect of both in a newly-designed experimental setting. Electrospun scaffolds of Nylon and PLGA/PCL and a non-porous PLGA/PCL film were clamped like a drumhead and seeded with fibroblasts of POP patients. Upon confluency, scaffolds were cyclically strained for 24 or 72 h at 10% and 0.2 Hz, mimicking gentle breathing. Non-loading condition was control. Strained fibroblasts loosened their actin-fibers, thereby preventing myofibroblastic differentiation. Mechanical loading upregulated genes involved in matrix synthesis (collagen I, III, V and elastin), matrix remodeling (α-SMA, TGF-ß1, MMP-2) and inflammation (COX-2, TNF-α, IL8, IL1-ß). Collagen genes were expressed earlier under mechanical loading and the ratio of I/III collagen increased. Matrix synthesis and remodeling were stronger on the electrospun scaffolds, while inflammation was more prominent on the non-porous film. Our findings indicate that mechanical straining enhances the regenerative potential of fibroblasts for the regeneration of fascia-type tissues and limit the risk of scar tissue formation. These effects are stronger on an electrospun texture. STATEMENT OF SIGNIFICANCE: Pelvic organ prolapsed is a dysfunctional disease in female pelvic floor that can reduce the quality of life women. Currently, trans-vaginal knitted meshes are used to anatomically correct the dysfunctional tissues. However, the meshes can create sever adverse complications in some patients (e.g. chronic pain) in longer-term. As an alternative, we developed nanofibrous matrices by electrospinning based on different materials. We designed an in-vitro culture system and subjected cell-seeded matrices to cyclic mechanical loading. Results revealed that gentle straining of POP-cells on electrospun matrices, advances their regenerative potential at morphological and gene expression levels. Our findings, provide a proof-of-concept for using electrospun matrices as an alternative implant for pelvic floor repair, given that the parameters are designed efficiently and safely.

Biomimetic implants for pelvic floor repair.

BACKGROUND: Polypropylene implants are used for the reconstructive surgery of urogynaecological disorders like pelvic organ prolapse, but severe complications associated with their use have been reported. There is evidence that surface properties and a difference in mechanical stiffness between the implant and the host tissue contribute to these adverse events. Electrospinning is an innovative engineering alternative that provides a biomimetic microstructure for implants, resulting in a different mechano-biological performance. AIM: The main objective of this review is to inform about the potential of electrospun matrices as an alternative modality for pelvic floor repair. METHODS: Publications with the following studies of electrospun matrices were reviewed: (i) the technique; (ii) in vitro use for soft tissue engineering; (iii) in vivo use for reconstruction of soft tissues in animals; and (iv) clinical use in humans. RESULTS: Electrospun matrices provide a synthetic mimic of natural extracellular matrix (ECM), favoring cellular attachment, proliferation and matrix deposition, through which a proper, low-inflammatory tissue-implant interaction can be established. Electrospun sheets can also be created with sufficient mechanical strength and stiffness for usage in prolapse surgery. CONCLUSION: Electrospun matrices mimic the structural topography of the extracellular matrix and can be functionalized for better biological performance. As such, they have great potential for the next generation of urogynecological implants. However, their long-term safety and efficacy must still be established in vivo.

Toward a new generation of pelvic floor implants with electrospun nanofibrous matrices: A feasibility study.

OBJECTIVE: The use of knitted, polypropylene meshes for the surgical treatment of pelvic organ prolapse (POP) is frequently accompanied by severe complications. Looking for alternatives, we studied the potential of three different electrospun matrices in supporting the adhesion, proliferation, and matrix deposition of POP and non-POP fibroblasts, the most important cells to produce extracellular matrix (ECM), in vitro. STUDY DESIGN: We electrospun three commonly used medical materials: nylon; poly (lactide-co-glycolide) blended with poly-caprolactone (PLGA/PCL); and poly-caprolactone blended with gelatin (PCL/Gelatin). The matrices were characterized for their microstructure, hydrophilicity, and mechanical properties. We seeded POP and non-POP fibroblasts from patients with POP and we determined cellular responses and ECM deposition. RESULTS: All matrices had >65% porosity, homogenous microstructures, and close to sufficient tensile strength for pelvic floor repair: 15.4 ± 3.3 MPa for Nylon; 12.4 ± 1.6 MPa for PLGA/PCL; and 3.5 ± 0.9 MPa for PCL/Gelatin. Both the POP and non-POP cells adhered to the electrospun matrices; they proliferated well and produced ample ECM. Overall, the best in vitro performance appeared to be on nylon, presumably because this was the most hydrophilic material with the thinnest fibers. CONCLUSION: Electrospun nanofibrous matrices show feasible mechanical strength and great biocompatibility for POP and non-POP fibroblasts to produce their ECM in vitro and, thus, may be candidates for a new generation of implants for pelvic floor repair. Further studies on electrospun nanofibrous matrices should focus on mechanical and immunological conditions that would be presented in vivo. Neurourol. Urodynam. 36:565-573, 2017. © 2016 Wiley Periodicals, Inc.

Electrospun Matrices for Pelvic Floor Repair: Effect of Fiber Diameter on Mechanical Properties and Cell Behavior.

Electrospun matrices are proposed as an alternative for polypropylene meshes in reconstructive pelvic surgery. Here, we investigated the effect of fiber diameter on (1) the mechanical properties of electrospun poly (lactic-co-glycolic acid)-blended-poly(caprolactone) (PLGA/PCL) matrices; (2) cellular infiltration; and (3) the newly formed extracellular matrix (ECM) in vitro. We compared electrospun matrices with 1- and 8 µm fiber diameter and used nonporous PLGA/PCL films as controls. The 8-µm matrices were almost twice as stiff as the 1-µm matrices with 1.38 and 0.66 MPa, respectively. Matrices had the same ultimate tensile strength, but with 80% the 1-µm matrices were much more ductile than the 8-µm ones (18%). Cells infiltrated deeper into the matrices with larger pores, but cellular activity was comparable on both substrates. New ECM was deposited faster on the electrospun samples, but after 2 and 4 weeks the amount of collagen was comparable with that on nonporous films. The ECM deposited on the 1-µm matrices, and the nonporous film was about three times stiffer than the ECM found on the 8-µm matrices. Cell behavior in terms of myofibroblastic differentiation and remodeling was similar on the 1-µm matrices and nonporous films, in comparison to that on the 8-µm matrices. We conclude that electrospinning enhances the integration of host cells as compared with a nonporous film of the same material. The 1-µm matrices result in better mechanical behavior and qualitatively better matrix production than the 8-µm matrices, but with limited cellular infiltration. These data are useful for designing electrospun matrices for the pelvic floor.