Silicate-substituted strontium apatite nano coating improves osteogenesis around artificial ligament

BMC Musculoskelet Disord. 2019 Aug 31;20(1):396. doi: 10.1186/s12891-019-2777-8.

Abstract

Background: Treatment of anterior cruciate ligament injuries commonly involves the use of polyethylene terephthalate (PET) artificial ligaments for reconstruction. However, the currently available methods require long fixation periods, thereby necessitating the development of alternative methods to accelerate the healing process between tendons and bones. Thus, we developed and evaluated a novel technique that utilizes silicate-substituted strontium (SrSiP).

Methods: PET films, nano-coated with SrSiP, were prepared. Bone marrow mesenchymal cells (BMSCs) from femurs of male rats were cultured and seeded at a density of 1.0 × 104/cm2 onto the SrSiP-coated and non-coated PET film, and subsequently placed in an osteogenic medium. The osteocalcin concentration secreted into the medium was compared in each case. Next, PET artificial ligament, nano-coated with SrSiP, were prepared. BMSCs were seeded at a density of 4.5 × 105/cm2 onto the SrSiP-coated, and non-coated artificial ligament, and then placed in osteogenic medium. The osteocalcin and calcium concentrations in the culture medium were measured on the 8th, 10th, 12th, and 14th day of culture. Furthermore, mRNA expression of osteocalcin, alkaline phosphatase (ALP), bone morphogenetic protein-2 (BMP2), and runt-related transcription factor 2 (Runx2) was evaluated by qPCR. We transplanted the SrSiP-coated and non-coated artificial ligament to the tibiae of mature New Zealand white rabbits. Two months later, we sacrificed them and histologically evaluated them.

Results: The secretory osteocalcin concentration in the medium on the film was significantly higher for the SrSiP group than for the non-coated group. Secretory osteocalcin concentration in the medium on the artificial ligament was also significantly higher in the SrSiP group than in the non-coated group on the 14th day. Calcium concentration on the artificial ligament was significantly lower in the SrSiP group than in the non-coated group on the 8th, 10th, 12th, and 14th day. In qPCR as well, OC, ALP, BMP2, and Runx2 mRNA expression were significantly higher in the SrSiP group than in the non-coated group. Newly formed bone was histologically found around the artificial ligament in the SrSiP group.

Conclusions: Our findings demonstrate that artificial ligaments using SrSiP display high osteogenic potential and thus may be efficiently used in future clinical applications.

Keywords: Anterior cruciate ligament injuries; Nano coating; Osteogenesis; PET artificial ligament; Silicate-substituted strontium.

MeSH terms

  • Animals
  • Anterior Cruciate Ligament Injuries / therapy*
  • Apatites / chemistry
  • Apatites / pharmacology
  • Bone-Implant Interface*
  • Calcium / metabolism
  • Cell Differentiation
  • Cells, Cultured
  • Coated Materials, Biocompatible / chemistry
  • Coated Materials, Biocompatible / pharmacology*
  • Coated Materials, Biocompatible / therapeutic use
  • Culture Media / analysis
  • Disease Models, Animal
  • Humans
  • Male
  • Materials Testing
  • Mesenchymal Stem Cells
  • Nanostructures / chemistry*
  • Osseointegration / drug effects
  • Osteocalcin / analysis
  • Osteocalcin / metabolism
  • Osteogenesis / drug effects
  • Polyethylene Terephthalates / chemistry
  • Polyethylene Terephthalates / pharmacology*
  • Polyethylene Terephthalates / therapeutic use
  • Primary Cell Culture
  • Rabbits
  • Rats
  • Silicates / pharmacology
  • Strontium / chemistry
  • Strontium / pharmacology
  • Time Factors
  • Wound Healing / drug effects

Substances

  • Apatites
  • Coated Materials, Biocompatible
  • Culture Media
  • Polyethylene Terephthalates
  • Silicates
  • Osteocalcin
  • Calcium
  • Strontium