Abstract
Therapies using mesenchymal stem cell (MSC) seeded scaffolds may be applicable to various fields of regenerative medicine, including craniomaxillofacial surgery. Plastic compression of collagen scaffolds seeded with MSC has been shown to enhance the osteogenic differentiation of MSC as it increases the collagen fibrillary density. The aim of the present study was to evaluate the osteogenic effects of dense collagen gel scaffolds seeded with mesenchymal dental pulp stem cells (DPSC) on bone regeneration in a rat critical-size calvarial defect model. Two symmetrical full-thickness defects were created (5 mm diameter) and filled with either a rat DPSC-containing dense collagen gel scaffold (n = 15), or an acellular scaffold (n = 15). Animals were imaged in vivo by microcomputer tomography (Micro-CT) once a week during 5 weeks, whereas some animals were sacrificed each week for histology and histomorphometry analysis. Bone mineral density and bone micro-architectural parameters were significantly increased when DPSC-seeded scaffolds were used. Histological and histomorphometrical data also revealed significant increases in fibrous connective and mineralized tissue volume when DPSC-seeded scaffolds were used, associated with expression of type I collagen, osteoblast-associated alkaline phosphatase and osteoclastic-related tartrate-resistant acid phosphatase. Results demonstrate the potential of DPSC-loaded-dense collagen gel scaffolds to benefit of bone healing process.
Highlights
A large variety of biomaterials has been used as carriers in bone tissue engineering approaches, including the widely used three dimensional (3D) collagen-based biomimetic hydrogel scaffolds[8,9]
We hypothesized that dense collagen scaffold, which constitutes a physiological osteogenic extracellular matrix due to its elevated fibrillar density, combined with mesenchymal stem cells derived from the dental pulp, would enhance bone regeneration
Most of passage 2 rat DPSC (rDPSC), represented by events from alive cells in both morphogate and singulet gates, were negative for CD31 and CD45, and >7 5% were positive for CD73 and CD90, as expected for mesenchymal stromal cells (Fig. 1)[39,40]
Summary
A large variety of biomaterials has been used as carriers in bone tissue engineering approaches, including the widely used three dimensional (3D) collagen-based biomimetic hydrogel scaffolds[8,9] These hydrogel scaffolds are biocompatible, biodegradable with low antigenicity, which provide a favorable environment to support osteoblast attachment, proliferation, and differentiation[10,11]. The “plastic compression” approach yields a type I collagen matrix with a fibrillar density similar to that of native bone matrix[14,15,16] This process enables the rapid, controllable and reproducible production of dense collagen gel scaffolds with highly defined meso-structure and increased biomechanical properties, similar to that of the osteoid[10,17,18]. The bone repair process was dynamically monitored in vivo, using micro-computed tomography and analyzed by histomorphometry
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