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.

Keywords: PLGA; bFGF; electrospinning; rat model; rotator cuff tear.

Figure 1

Augmentation of RCT repair with bFGF-loaded electrospun fibrous membranes. Abbreviations: bFGF, basic fibroblast growth factor; RCT, rotator cuff tear.

Figure 2

SEM images of electrospun PLGA (A) and bFGF–PLGA (B); TEM images of electrospun PLGA (C) and bFGF–PLGA (D) fibers. Abbreviations: bFGF, basic fibroblast growth factor; PLGA, poly(lactide-co-glycolide); SEM, scanning electron microscopy; TEM, transmission electron microscopy.

Figure 3

In vitro bFGF release profiles of bFGF–PLGA fibrous membranes. Abbreviations: bFGF, basic fibroblast growth factor; PLGA, poly(lactide-co-glycolide).

Figure 4

SEM images of HDF growth on the electrospun PLGA. Notes: (A) and bFGF–PLGA; (B) fibrous membranes at 5 days after seeding; (C) CCK-8 assay of HDF proliferation on the electrospun fibrous membranes. *Represents P<0.05 compared to the corresponding PLGA group. Abbreviations: bFGF, basic fibroblast growth factor; HDF, human dermal fibroblasts; PLGA, poly(lactide-co-glycolide); SEM, scanning electron microscopy.

Figure 5

Representative hematoxylin and eosin-stained tissue sections. Notes: (A) 100× and (B) 200× of the tendon insertion site at 2, 4, and 8 weeks postoperatively. The green arrow indicates degraded fibrous membrane, the yellow triangle indicates fibroblasts, and the red circle indicates microvessels. Abbreviations: bFGF, basic fibroblast growth factor; PLGA, poly(lactide-co-glycolide); W, weeks.

Figure 6

Representative histological images of cartilage at the insertion site (A) 100×, and area of cartilage present at the insertion site as determined by metachromasia with Safranin O-stained slides (B). Notes: The results are shown as the mean ± SD; *represents P<0.05 versus control; ^▲represents P<0.05 versus PLGA; n=8 for each group. Abbreviations: bFGF, basic fibroblast growth factor; PLGA, poly(lactide-co-glycolide); W, weeks; SD, standard deviation.

Figure 7

Representative Picro Sirius red-stained tissue sections of the healing enthesis (A) 100× and analysis of collagen birefringence (B). Notes: The results are shown as the mean ± SD; *represents P<0.05 versus control; ^▲represents P<0.05 versus PLGA; n=8 for each group. Abbreviations: bFGF, basic fibroblast growth factor; PLGA, poly(lactide-co-glycolide); W, weeks; SD, standard deviation.

Figure 8

The cross-sectional area of the tendon at the insertion site (A), and biomechanical testing of ultimate load-to-failure (B), stiffness (C), and ultimate stress-to-failure (D). Notes: The results are shown as the mean ± SD; *represents P<0.05 versus control; ^▲represents P<0.05 versus PLGA; n=8 for each group. Abbreviations: bFGF, basic fibroblast growth factor; PLGA, poly(lactide-co-glycolide); W, weeks; SD, standard deviation.