Biodegradable composite scaffolds incorporating an intramedullary rod and delivering bone morphogenetic protein-2 for stabilization and bone regeneration in segmental long bone defects

Abstract

In this study, a two part bone tissue engineering scaffold was investigated consisting of a solid poly(propylene fumarate) (PPF) intramedullary rod for mechanical support surrounded by a porous PPF sleeve for osseointegration and delivery of poly(DL-lactic-co-glycolic acid) (PLGA) microspheres with adsorbed recombinant human bone morphogenetic protein-2 (rhBMP-2). Scaffolds were implanted into critical size rat segmental femoral defects with internal fixation for 12 weeks. Bone formation was assessed throughout the study via radiography, and following euthanasia via micro-CT and histology. Mechanical stabilization was evaluated further via torsional testing. Experimental implant groups included the PPF rod alone and the rod with a porous PPF sleeve containing PLGA microspheres with 0, 2, or 8 μg of rhBMP-2 adsorbed onto their surface. Results showed that presence of the scaffold increased mechanical stabilization of the defect, as evidenced by the increased torsional stiffness of the femurs by the presence of a rod compared to the empty defect. Although the presence of a rod decreased bone formation, the presence of a sleeve combined with a low or high dose of rhBMP-2 increased the torsional stiffness to 2.06 ± 0.63 N·mm and 1.68 ± 0.56 N·mm, respectively, from 0.56 ± 0.24 N·mm for the rod alone. The results indicate that, while scaffolds may provide structural support to regenerating tissues and increase their mechanical properties, the presence of scaffolds within defects may hinder overall bone formation if they interfere with cellular processes.

Injectable dual-gelling cell-laden composite hydrogels for bone tissue engineering

“…The percent of bone formation, including hydrogel mineralization, within the defect was determined by centering a cylindrical volume of interest (VOI) of 8 mm in diameter and 2 mm in height at the bottom of the defect. Data are reported as the % binarized object volume measured within this VOI within thresholding gray values (70–255) with the CT-analysis software [15]. The extent of bony bridging and union within the defect were scored according to the grading scale in Supplementary Figure 1 using microCT generated maximum intensity projections of the samples.…”

Enhancing the bioactivity of Poly(lactic-co-glycolic acid) scaffold with a nano-hydroxyapatite coating for the treatment of segmental bone defect in a rabbit model

“…Owing to these features, porous PLGA scaffolds have been widely used in tissue engineering, including for the treatment of bone defects. 6,[27][28][29][30] While PLGA scaffolds have many advantages, their limited abilities regarding osteoconduction and osteoinduction hinder their application in bone tissue engineering. The surface characteristics of biomedical implants play an important role in implanting and eventual osteointegration.…”

A Review on Biodegradable Polymeric Materials Striving Towards the Attainment of Green Environment

“…These unique characteristics find application as three-dimensional substrate in bone tissue engineering. [58] investigated the radiography, m-CT, histology, mechanical behavior of solid PPF intramedullary rod reinforced porous PPF sleeve composites. In addition, PLGA microspheres were incorporated onto the developed composites.…”