Biological augmentation of rotator cuff repair using bFGF-loaded electrospun poly(lactide-co-glycolide) fibrous membranes

Abstract

Clinically, rotator cuff tear (RCT) is among the most common shoulder pathologies. Despite significant advances in surgical techniques, the re-tear rate after rotator cuff (RC) repair remains high. Insufficient healing capacity is likely the main factor for reconstruction failure. This study reports on a basic fibroblast growth factor (bFGF)-loaded electrospun poly(lactide-co-glycolide) (PLGA) fibrous membrane for repairing RCT. Implantable biodegradable bFGF–PLGA fibrous membranes were successfully fabricated using emulsion electrospinning technology and then characterized and evaluated with in vitro and in vivo cell proliferation assays and repairs of rat chronic RCTs. Emulsion electrospinning fabricated ultrafine fibers with a core-sheath structure which secured the bioactivity of bFGF in a sustained manner for 3 weeks. Histological observations showed that electrospun fibrous membranes have excellent biocompatibility and biodegradability. At 2, 4, and 8 weeks after in vivo RCT repair surgery, electrospun fibrous membranes significantly increased the area of glycosaminoglycan staining at the tendon–bone interface compared with the control group, and bFGF–PLGA significantly improved collagen organization, as measured by birefringence under polarized light at the healing enthesis compared with the control and PLGA groups. Biomechanical testing showed that the electrospun fibrous membrane groups had a greater ultimate load-to-failure and stiffness than the control group at 4 and 8 weeks. The bFGF–PLGA membranes had the highest ultimate load-to-failure, stiffness, and stress of the healing enthesis, and their superiority compared to PLGA alone was significant. These results demonstrated that electrospun fibrous membranes aid in cell attachment and proliferation, as well as accelerating tendon–bone remodeling, and bFGF-loaded PLGA fibrous membranes have a more pronounced effect on tendon–bone healing. Therefore, augmentation using bFGF–PLGA electrospun fibrous membranes is a promising treatment for RCT.

Catalytic activity of trypsin entrapped in electrospun poly(ϵ-caprolactone) nanofibers

“…2(B) reveals the rod-like morphology of the main fiber segments and their smooth surface. Although, emulsion electrospinning has been used for the preparation of coaxial fibers [13,16,32,33], with a core-shell organization, in the present case it was not intended to obtain this kind of fiber morphology or organization, but rather a distribution of the aqueous phase, and thus the enzyme, throughout the fiber, preferably near the surface, minimizing leakage of the enzyme but assuring satisfactory accessibility of the substrates. In fact, under the selected electrospinning conditions and emulsion properties, the electrospun fibers did not show any phase separation or coaxial distribution, as observed by TEM analysis (Fig.…”

“…Electrospinning provides a simple and versatile method to make nano-or sub-micronfibrous supports, showing many advantages for enzyme immobilization [9][10][11]. In addition, emulsion electrospinning is an advantageous strategy to encapsulate sensitive compounds, especially those susceptible to the external conditions (solvent, pH, temperature) including enzymes [12][13][14][15][16]. The high porosity and interconnectivity of the fiber arrays, combined with the large surface area per mass unit, satisfactory mechanical properties and the chemical and physical versatility of the nanofibrous electrospun materials, typically allow for high enzyme loads, high adaptability enabling the surface attachment and/or the entrapment of enzymes, adequate substrate accessibility, improved mass-transfer rates and the possibility of large scale productions and continuous processes [17,18].…”

Biologic and Tissue Engineering Strategies for Tendon Repair

“…BMP-2 [28,29], bFGF [56], and PDGF-BB [70,71] all increased the strength and enhanced the tensile properties of repairs at the tendon insertion site, and BMP-2 and PDGF-BB administration resulted in regeneration of an enthesis-like structure [28,70]. MSC [11] and BMAC [113] administration for insertion-site defects also resulted in multilayered, organized enthesis structures, and periosteal cells were similarly effective due to their ability to differentiate into osteocytes or chondrocytes.…”

“…Alternative growth factor delivery systems, such as scaffolds, may enhance or prolong bFGF's healing potential. Zhao et al found that bFGFseeded electrospun, randomly aligned PGLA scaffolds (at a dosage of 20 μg/mL), significantly improved collagen organization at all time points (22.6 ± 0.7 gray-scale units at 2 weeks, 32.7 ± 0.8 at 4 weeks, and 45.4 ± 1.2 at 8 weeks vs. 20.5 ± 0.9, 31.4 ± 0.7, and 43.8 ± 1.0 for scaffolds without bFGF), ultimate failure load at 4 and 8 weeks (21.4 ± 1.3 N and 32.7 ± 1.0 N for the PGLA + bFGF vs. 20.7 ± 1.6 N and 28.4 ± 1.2 N for PGLA), ultimate stress at 8 weeks (1.82 ± 0.03 vs. 1.62 ± 0.03 MPa), and stiffness at 8 weeks (14.9 vs. 13.7 N/ mm) in a rat model of rotator cuff repair [56], and administration of a fibrin sealant with bFGF (100 μg/kg) in conjugation with acellular dermal grafts significantly improved tendon maturity scores (24.3 ± 1.0 vs. 20.6 ± 2.6 out of 28 at 6 weeks, 26.7 ± 0.8 vs. 25.2 ± 0.5 at 12 weeks) and ultimate failure loads (10.2 ± 3.1 N vs. 7.2 ± 2.2 N at 6 weeks, 15.9 ± 1.6 N vs. 13.2 ± 2.0 N at 12 weeks) relative to the graft + fibrin group in a rat model of rotator cuff repair [57].…”

“…Tendons treated with 1000 ng bFGF had a mean Col-I/Col-III ratio of 3.4, whereas the operative repair group had a mean Col-1/Col-III ratio of 4.3 [58]. Zhao et al [56] demonstrated that bFGF delivered at high doses via fibrin matrices can enhance tendon repair in a rat model; the findings of Thomopoulos et al may indicate that bFGF has adverse effects that are more pronounced in a canine model. Gene therapy has also been used to upregulate bFGF expression.…”