Poly(lactic-co-glycolide) polymer constructs cross-linked with human BMP-6 and VEGF protein significantly enhance rat mandible defect repair

• Published in: Cell and tissue research Vol. 364; no. 1; pp. 125 - 135
• Main Authors: Das, Anusuya, Fishero, Brian A., Christophel, J. Jared, Li, Ching-Ju, Kohli, Nikita, Lin, Yong, Dighe, Abhijit S., Cui, Quanjun
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-04-2016; Springer; Springer Nature B.V
• Subjects: Animals; Biomedical and Life Sciences; Biomedicine; Bone Morphogenetic Protein 6 - chemistry; Bone Morphogenetic Protein 6 - pharmacology; Bone morphogenetic proteins; Human Genetics; Humans; Lactic Acid - chemistry; Lactic Acid - pharmacology; Mandible - metabolism; Mandible - pathology; Mandibular Diseases - pathology; Mandibular Diseases - therapy; Mesenchymal Stromal Cells - metabolism; Mesenchymal Stromal Cells - pathology; Molecular Medicine; Polyglycolic Acid - chemistry; Polyglycolic Acid - pharmacology; Polymers; Proteins; Proteomics; Rats; Rats, Inbred F344; Regular Article; Rodents; Stem cells; Tissue Scaffolds - chemistry; Vascular endothelial growth factor; Vascular Endothelial Growth Factor A - chemistry; Vascular Endothelial Growth Factor A - pharmacology; BMP-6; Rat (Sprague Dawley); Crosslinked PLAGA; VEGF; Mandibular bone repair; Vascularization
• ISSN: 0302-766X; 1432-0878
• DOI: 10.1007/s00441-015-2301-x

We have previously shown that the combined delivery of mesenchymal stem cells (MSCs), vascular endothelial growth factor (VEGF) and bone morphogenetic protein 6 (BMP-6) induces significantly more bone formation than that induced by the delivery of any single factor or a combination of any two factors. We now determine whether the exogenous addition of VEGF and BMP-6 is sufficient for bone healing when MSCs are not provided. Poly(lactic-co-glycolic acid) (PLAGA) microsphere-based three-dimensional scaffolds (P) were fabricated by thermal sintering of PLAGA microspheres. The scaffolds were chemically cross-linked with 200 ng recombinant human VEGF (PⱽᴱᴳF) or BMP-6 (Pᴮᴹᴾ⁻⁶) or both (PⱽᴱᴳF⁺ᴮᴹᴾ⁻⁶) by the EDC-NHS-MES method. Release of the proteins from the scaffolds was detected for 21 days in vitro which confirmed their comparable potential to supply the proteins in vivo. The scaffolds were delivered to a critical-sized mandibular defect created in 32 Sprague Dawley rats. Significant bone regeneration was observed only in rats with PⱽᴱᴳF⁺ᴮᴹᴾ⁻⁶ scaffolds at weeks 2, 8 and 12 as revealed by micro-computer tomography. Vascular ingrowth was higher in the PⱽᴱᴳF⁺ᴮᴹᴾ⁻⁶ group as seen by microfil imaging than in other groups. Trichrome staining revealed that a soft callus formed in PⱽᴱᴳF, Pᴮᴹᴾ⁻⁶ and PⱽᴱᴳF⁺ᴮᴹᴾ⁻⁶ but not in P. MSCs isolated from rat femurs displayed expression of the bone-specific marker osteocalcin when cultured with PⱽᴱᴳF, Pᴮᴹᴾ⁻⁶, or PⱽᴱᴳF⁺ᴮᴹᴾ⁻⁶ but not with P. Robust mineralization and increased alkaline phosphatase gene expression were seen in rat MSCs when cultured on PⱽᴱᴳF⁺ᴮᴹᴾ⁻⁶ but not on P, PⱽᴱᴳF, or Pᴮᴹᴾ⁻⁶. Thus, unlike the delivery of VEGF or BMP-6 alone, the combined delivery of VEGF and BMP-6 to the bone defect significantly enhanced bone repair through the enhancement of angiogenesis and the differentiation of endogenously recruited MSCs into the bone repair site.