Enhancement of osseointegration of polyethylene terephthalate artificial ligament by coating of silk fibroin and depositing of hydroxyapatite

Abstract

Background Application of artificial ligament in anterior cruciate ligament reconstruction is one of the research focuses of sports medicine but the biological tendon–bone healing still remains a problem. The preliminary study of hydroxyapatite (HAP) coating on the polyethylene terephthalate (PET) surface could effectively induce the osteoblast differentiation, but the tendon–bone healing was still not stable. As a green synthesis process, the biomimetic mineralization can simulate the natural bone growth in vitro and in vivo. Methods HAP crystals were grown under the guide of silk fibroin (SF) PET surface by biomimetic route. Several techniques including scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy were utilized for proving the introduction of both SF and HAP. The viability and osseointegration of bone marrow stromal cells on the surface of three kinds of ligament, including PET group (non-coating group), PET+SF group (SF-coating group), and PET+SF+HAP group (combined HAP- and SF-coating group), were analyzed by CCK-8 assays and alkaline phosphatase (ALP) detection. Seventy-two mature male New Zealand rabbits were randomly divided into three groups. Among them, 36 rabbits were sacrificed for mechanical testing, and histological examination for the others. Results The SF and SF+HAP were successfully coated on the surface of PET fiber. The CCK-8 assay showed that the cell proliferation on PET+SF+HAP group was better than the other two groups from 24 to 120 hours. After 14 days of culture, the cells in the PET+SF+HAP group delivered higher levels of ALP than the other two groups. After 3 days of culture, the expression level of integrin β1 in the PET+SF+HAP group and PET+SF group were higher than in the PET group. The mean load to failure and the stiffness value of the PET+SF+HAP group were both higher than the other two groups. Hematoxylin and eosin staining showed that new bone tissue formation was only found in the PET+SF+HAP group 8 weeks postoperatively. Masson staining showed that in the PET+SF+HAP group 8 weeks postoperatively, the PET fibers were almost completely encircled by collagen. Histomorphometric analysis showed that the width of the graft–bone interface in the PET+SF+HAP group was narrower than that in the other two groups 4 and 8 weeks postoperatively. The mRNA level of BMP-7 in the PET+SF+HAP groups was significantly higher than those in the other two groups 4 and 8 weeks postoperatively. Conclusion The study showed that the combined SF and HAP coating by biomimetic route on the surface of PET artificial ligament could induce graft osseointegration in the bone tunnel, providing theoretical and experimental foundation for manufacturing novel artificial ligaments meeting the clinical needs.

Surface modification of vascular endothelial growth factor-loaded silk fibroin to improve biological performance of ultra-high-molecular-weight polyethylene via promoting angiogenesis

“…The characteristic peaks of UHMWPE at 719, 729, 1,463, 2,850, and 2,913/cm were ascribed to the 26 After samples were immersed in SF solution and tested, the typical peaks of SF at 1,629/cm (for amide I) and 1,520/cm (for amide II) exhibited, which proved that there was some β-sheet formation of SF. 25 This result verified that the UHMWPE fibers were coated by SF and in agreement with the FESEM results. There were no new characteristic peaks observed after the introduction of VEGF because the spectrum of SF was similar to the spectrum of SF.…”

“…23 SF scaffold has been proved to be a suitable vehicle to release VEGF in vivo and subsequently induce the homing and differentiation of MSCs. 24,25 Therefore, we hypothesized that SF coating loaded with VEGF has a positive effect on the improvement of biological performance of UHMWPE.…”

Local delivery of controlled-release simvastatin to improve the biocompatibility of polyethylene terephthalate artificial ligaments for reconstruction of the anterior cruciate ligament

“…Previous studies showed that we can modify the graft surface property by coating with biocompatible, cytophilic, osteoinductive molecules or hydrophilic natural polymers. 26,27 Therefore, we hypothesized that if we combined a biocompatible collagen coating with low-dose SIM microsphere, this coating might enhance the biocompatibility of PET artificial ligament graft, and the SIM microsphere can release low-dose SIM in a sustainable manner to promote bone regeneration ( Figure 1). The purpose…”

Silk‐Based Biomaterials in Biomedical Textiles and Fiber‐Based Implants

“…The study showed that the combined SF and HAP coating on the surface of PET artificial ligaments induced graft osseointegration in bone tunnels. [203] . Zhang et al (2014) used poly(lactide-co-glycolide) (PLGA, 10:90) fibers to adjust the degradation rate of the scaffolds and filled them with collagen to reserve space for cell ingrowth.…”