Poster Presentations

Start Date

20-5-2014 12:30 PM

Description

For graft-assisted repair of large volumetric bone loss resulting from traumatic orthopedic injuries, strategies that simultaneously promote osteointegration/graft healing and mitigate risks for infections are highly desired. Previously, we developed a poly(2-hydroxyethyl methacrylate)-nanocrystalline hydroxyapatite (pHEMA-nHA) composite as a synthetic bone graft. The composite, when loaded with a single dose of 400-ng rhBMP-2/7 and press-fit into a 5-mm rat femoral segmental defect, led to bony callus fully bridging over the defect and substantial restoration of the torsional rigidity by 12 weeks. More recently, we showed that 4.8 wt% vancomycin can be encapsulated within the composite without compromising the structural and mechanical integrity. Additionally, FDA-approved rhBMP-2 can be absorbed onto the graft and both the vancomycin and rhBMP-2 can be released in a localized and sustained manner. Here we examine the efficacy of pHEMA-nHA-vancomycin grafts pre-absorbed with rhBMP-2 in repairing 5-mm rat femoral segmental defects, and determine if vancomycin hinders the repair. pHEMA-nHA-vancomycin or pHEMA-nHA with/without 3-µg rhBMP-2 were press-fit in 5-mm femoral defects in male rats. Histology, microcomputed tomography, and torsion testing were performed on 12-week explants to evaluate the extent and quality of repair. Partial bridging of the defect with bony callus by 12 weeks was observed with pHEMA-nHA-vancomycin without rhBMP-2 while full bridging with substantially mineralized callus and partial restoration of torsional strength was achieved with 3-µg rhBMP-2. The presence of vancomycin did not significantly compromise graft healing. The pHEMA-nHA-vancomycin graft, with the ability to deliver safe doses of osteogenic recombinant proteins and to simultaneously release the encapsulated antibiotics in a sustained manner holds promise in improving the clinical outcome of graft-assisted repair of traumatic bone injuries.

Comments

Abstract of poster presented at the 2014 UMass Center for Clinical and Translational Science Research Retreat, held on May 20, 2014 at the University of Massachusetts Medical School, Worcester, Mass.

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Creative Commons Attribution-Noncommercial-Share Alike 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 License.

 
May 20th, 12:30 PM

Vancomycin-bearing Synthetic Bone Graft Delivers rhBMP-2 and Promotes Healing of Critical Rat Femoral Segmental Defects

For graft-assisted repair of large volumetric bone loss resulting from traumatic orthopedic injuries, strategies that simultaneously promote osteointegration/graft healing and mitigate risks for infections are highly desired. Previously, we developed a poly(2-hydroxyethyl methacrylate)-nanocrystalline hydroxyapatite (pHEMA-nHA) composite as a synthetic bone graft. The composite, when loaded with a single dose of 400-ng rhBMP-2/7 and press-fit into a 5-mm rat femoral segmental defect, led to bony callus fully bridging over the defect and substantial restoration of the torsional rigidity by 12 weeks. More recently, we showed that 4.8 wt% vancomycin can be encapsulated within the composite without compromising the structural and mechanical integrity. Additionally, FDA-approved rhBMP-2 can be absorbed onto the graft and both the vancomycin and rhBMP-2 can be released in a localized and sustained manner. Here we examine the efficacy of pHEMA-nHA-vancomycin grafts pre-absorbed with rhBMP-2 in repairing 5-mm rat femoral segmental defects, and determine if vancomycin hinders the repair. pHEMA-nHA-vancomycin or pHEMA-nHA with/without 3-µg rhBMP-2 were press-fit in 5-mm femoral defects in male rats. Histology, microcomputed tomography, and torsion testing were performed on 12-week explants to evaluate the extent and quality of repair. Partial bridging of the defect with bony callus by 12 weeks was observed with pHEMA-nHA-vancomycin without rhBMP-2 while full bridging with substantially mineralized callus and partial restoration of torsional strength was achieved with 3-µg rhBMP-2. The presence of vancomycin did not significantly compromise graft healing. The pHEMA-nHA-vancomycin graft, with the ability to deliver safe doses of osteogenic recombinant proteins and to simultaneously release the encapsulated antibiotics in a sustained manner holds promise in improving the clinical outcome of graft-assisted repair of traumatic bone injuries.

 

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