Use of an anionic collagen matrix made from bovine intestinal serosa for in vivo repair of cranial defects

Abstract

Polymeric biomaterials composed of extracellular matrix components possess osteoconductive capacity that is essential for bone healing. The presence of collagen and the ability to undergo physicochemical modifications render these materials a suitable alternative in bone regenerative therapies. The objective of this study was to evaluate the osteogenic capacity of collagen-based matrices (native and anionic after alkaline hydrolysis) made from bovine intestinal serosa (MBIS). Twenty-five animals underwent surgery to create a cranial defect to be filled with native and anionic collagen matrixes, mmineralized and non mineralized. The animals were killed painlessly 6 weeks after surgery and samples of the wound area were submitted to routine histology and morphometric analysis. In the surgical area there was new bone formation projecting from the margins to the center of the defect. More marked bone neoformation occurred in the anionic matrices groups in such a way that permitted union of the opposite margins of the bone defect. The newly formed bone matrix exhibited good optical density of type I collagen fibers. Immunoexpression of osteocalcin by osteocytes was observed in the newly formed bone. Morphometric analysis showed a greater bone volume in the groups receiving the anionic matrices compared to the native membranes. Mineralization of the biomaterial did not increase its osteoregenerative capacity. In conclusion, the anionic matrix exhibits osteoregenerative capacity and is suitable for bone reconstruction therapies.

Fig 1

Thermogravimetric curves obtained for the different collagen matrices: (A) NBS, (B) BS24, (C) MNBS, and (D) MBS24.

Fig 2

EDX spectra for MBS24 (A) and MNBS (B).

Fig 3

SEM photomicrographs of native bovine serosa: (A) NBS (magnification 2,000x); (B) MNBS (magnification 2,000x); (C) MNBS (magnification 35,000x).

Fig 4

SEM photomicrographs of bovine serosa submitted to alkaline treatment: (A) BS24 (magnification 1,000x); (B) MBS24 (magnification 2,000x); (C) MBS24 (magnification 35,000x).

Fig 5. Photomicrographs of the defect area stained with Masson’s trichrome and immunohistochemistry.

Note the formation of new bone (*) from the original bone (OB) and osteocalcin staining (brown color) in osteocytes (arrows).

Fig 6. Photomicrographs of the defect area stained with picrosirius red.

Observe the birefringence of collagen fibers in the area of newly formed bone (*). OB: original bone.

Fig 7. Percentage (%) of newly formed bone in the studied groups.