Evaluation of a bioengineered ACL matrix's osteointegration with BMP-2 supplementation

PLoS One. 2020 Jan 7;15(1):e0227181. doi: 10.1371/journal.pone.0227181. eCollection 2020.

Abstract

A poly (l-lactic) acid bioengineered anterior cruciate ligament (ACL) matrix has previously demonstrated the ability to support tissue regeneration in a rabbit ACL reconstruction model. The matrix was designed for optimal bone and ligament regeneration by developing a matrix with differential pore sizes in its bone and ligament compartments. Building upon past success, we designed a new bioengineered ACL matrix that is easier to install and can be used with endobutton fixation during ACL reconstruction. To achieve this, a new braiding procedure was developed to allow the matrix to be folded in half, making two-limbs, while maintaining its bone and ligament compartments. The osteointegration of the matrix with and without bone morphogenetic protein 2 (BMP-2) supplementation was evaluated in a rabbit ACL reconstruction model. Two doses of BMP-2 were evaluated, 1 and 10 μg, and delivered by saline injection into the bone tunnel at the end of surgery. A fibrous matrix-to-bone interface with occasional Sharpey's fibers was the primary mode of osteointegration observed. The matrix was also found to support a fibrocartilage matrix-to-bone interface. In some cases, the presence of chondrocyte-like cells was observed at the aperture of the bone tunnel and the center of the matrix within the bone tunnel. Treatment with BMP-2 was associated with a trend towards smaller bone tunnel cross-sectional areas, and 1 μg of BMP-2 was found to significantly enhance osteoid seam width in comparison with no BMP-2 or 10 μg of BMP-2 treatment. Regenerated tissue was well organized within the bioengineered ACL matrix and aligned with the poly (l-lactic) acid fibers. Disorganized tissue was found between the two-limbs of the bioengineered ACL matrix and hypothesized to be due to a lack of structural scaffolding. This study suggests that the bioengineered ACL matrix can undergo similar modes of osteointegration as current autografts and allografts, and that BMP-2 treatment may enhance osteoblastic activity within the bone tunnels.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anterior Cruciate Ligament / diagnostic imaging
  • Anterior Cruciate Ligament / surgery
  • Anterior Cruciate Ligament Injuries / surgery*
  • Anterior Cruciate Ligament Reconstruction / instrumentation*
  • Anterior Cruciate Ligament Reconstruction / methods
  • Bone Morphogenetic Protein 2 / administration & dosage*
  • Disease Models, Animal
  • Feasibility Studies
  • Humans
  • Materials Testing
  • Microscopy, Electron, Scanning
  • Osseointegration / drug effects*
  • Polyesters / chemistry
  • Rabbits
  • Recombinant Proteins / administration & dosage
  • Tibia / diagnostic imaging
  • Tibia / physiology
  • Tibia / surgery
  • Tissue Engineering
  • Tissue Scaffolds / chemistry*
  • X-Ray Microtomography

Substances

  • BMP2 protein, human
  • Bone Morphogenetic Protein 2
  • Polyesters
  • Recombinant Proteins
  • poly(lactide)