239 research outputs found
Biphasic Calcium Phosphate Ceramics for Bone Regeneration and Tissue Engineering Applications
Biphasic calcium phosphates (BCP) have been sought after as biomaterials for the reconstruction of bone defects in maxillofacial, dental and orthopaedic applications. They have demonstrated proven biocompatibility, osteoconductivity, safety and predictability in in vitro, in vivo and clinical models. More recently, in vitro and in vivo studies have shown that BCP can be osteoinductive. in the field of tissue engineering, they represent promising scaffolds capable of carrying and modulating the behavior of stem cells. This review article will highlight the latest advancements in the use of BCP and the characteristics that create a unique microenvironment that favors bone regeneration.New Jersey Inst Technol, Dept Biomed Engn, Newark, NJ 07102 USAUniversidade Federal de São Paulo, Dept Morphol, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Morphol, BR-04023900 São Paulo, BrazilWeb of Scienc
Implantation of canine umbilical cord blood-derived mesenchymal stem cells mixed with beta-tricalcium phosphate enhances osteogenesis in bone defect model dogs
This study was performed to evaluate the osteogenic effect of allogenic canine umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) mixed with beta-tricalcium phosphate (β-TCP) in orthotopic implantation. Seven hundred milligrams of β-TCP mixed with 1 × 106 UCB-MSCs diluted with 0.5 ml of saline (group CM) and mixed with the same volume of saline as control (group C) were implanted into a 1.5 cm diaphyseal defect and wrapped with PLGC membrane in the radius of Beagle dogs. Radiographs of the antebrachium were made after surgery. The implants were harvested 12 weeks after implantation and specimens were stained with H&E, toluidine blue and Villanueva-Goldner stains for histological examination and histomorphometric analysis of new bone formation. Additionally, UCB-MSCs were applied to a dog with non-union fracture. Radiographically, continuity between implant and host bone was evident at only one of six interfaces in group C by 12 weeks, but in three of six interfaces in group CM. Radiolucency was found only near the bone end in group C at 12 weeks after implantation, but in the entire graft in group CM. Histologically, bone formation was observed around β-TCP in longitudinal sections of implant in both groups. Histomorphometric analysis revealed significantly increased new bone formation in group CM at 12 weeks after implantation (p < 0.05). When applied to the non-union fracture, fracture healing was identified by 6 weeks after injection of UCB-MSCs. The present study indicates that a mixture of UCB-MSCs and β-TCP is a promising osteogenic material for repairing bone defects
Multipotential stromal cell abundance in cellular bone allograft: comparison with fresh age-matched iliac crest bone and bone marrow aspirate
Aim: To enumerate and characterize multipotential stromal cells (MSCs) in a cellular bone allograft and compare with fresh age-matched iliac crest bone and bone marrow (BM) aspirate.
Materials and methods: MSC characterization used functional assays, confocal/scanning electron microscopy and whole-genome microarrays. Resident MSCs were enumerated by flow cytometry following enzymatic extraction.
Results: Allograft material contained live osteocytes and proliferative bone-lining cells defined as MSCs by phenotypic and functional capacities. Without cultivation/expansion, the allograft displayed an 'osteoinductive' molecular signature and the presence of CD45-CD271+CD73+CD90+CD105+ MSCs; with a purity over 100-fold that of iliac crest bone. In comparison with BM, MSC numbers enzymatically released from 1 g of cellular allograft were equivalent to approximately 45 ml of BM aspirate.
Conclusion: Cellular allograft bone represents a unique nonimmune material rich in MSCs and osteocytes. This osteoinductive graft represents an attractive alternative to autograft bone or composite/synthetic grafts in orthopedics and broader regenerative medicine settings
Formation of bone-like apatite layer on chitosan fiber mesh scaffolds by a biomimetic spraying process
Bone-like apatite coating of polymeric substrates
by means of biomimetic process is a possible
way to enhance the bone bonding ability of the
materials. The created apatite layer is believed to have
an ability to provide a favorable environment for
osteoblasts or osteoprogenitor cells. The purpose of
this study is to obtain bone-like apatite layer onto
chitosan fiber mesh tissue engineering scaffolds, by
means of using a simple biomimetic coating process
and to determine the influence of this coating on
osteoblastic cell responses. Chitosan fiber mesh scaffolds
produced by a previously described wet spinning
methodology were initially wet with a Bioglass"–water
suspension by means of a spraying methodology and
then immersed in a simulated body fluid (SBF)
mimicking physiological conditions for one week. The
formation of apatite layer was observed morphologically
by scanning electron microscopy (SEM). As a
result of the use of the novel spraying methodology, a
fine coating could also be observed penetrating into the
pores, that is clearly within the bulk of the scaffolds.
Fourier Transform Infrared spectroscopy (FTIRATR),
Electron Dispersive Spectroscopy (EDS) and
X-ray diffraction (XRD) analysis also confirmed the
presence of apatite-like layer. A human osteoblast-like
cell line (SaOs-2) was used for the direct cell contact assays. After 2 weeks of culture, samples were observed
under the SEM. When compared to the control
samples (unmodified chitosan fiber mesh scaffolds) the
cell population was found to be higher in the Ca–P
biomimetic coated scaffolds, which indicates that the
levels of cell proliferation on this kind of scaffolds
could be enhanced. Furthermore, it was also observed
that the cells seeded in the Ca–P coated scaffolds have
a more spread and flat morphology, which reveals an
improvement on the cell adhesion patterns, phenomena
that are always important in processes such as
osteoconduction
Gene-enhanced tissue engineering for dental hard tissue regeneration: (1) overview and practical considerations
Gene-based therapies for tissue regeneration involve delivering a specific gene to a target tissue with the goal of changing the phenotype or protein expression profile of the recipient cell; the ultimate goal being to form specific tissues required for regeneration. One of the principal advantages of this approach is that it provides for a sustained delivery of physiologic levels of the growth factor of interest. This manuscript will review the principals of gene-enhanced tissue engineering and the techniques of introducing DNA into cells. Part 2 will review recent advances in gene-based therapies for dental hard tissue regeneration, specifically as it pertains to dentin regeneration/pulp capping and periodontal regeneration
The roles of immune cells in bone healing; what we know, do not know and future perspectives
Key events occurring during the bone healing include well-orchestrated and complex interactions between immune cells, multipotential stromal cells (MSCs), osteoblasts and osteoclasts. Through three overlapping phases of this physiological process, innate and adaptive immune cells, cytokines and chemokines have a significant role to play. The aim of the escalating immune response is to achieve an osseous healing in the shortest time and with the least complications facilitating the restoration of function. The uninterrupted progression of these biological events in conjunction with a favourable mechanical environment (stable fracture fixation) remains the hallmark of successful fracture healing. When failure occurs, either the biological environment or the mechanical one could have been disrupted. Not infrequently both may be compromised. Consequently, regenerative treatments involving the use of bone autograft, allograft or synthetic matrices supplemented with MSCs are increasingly used. A better understanding of the bone biology and osteoimmunology can help to improve these evolving cell-therapy based strategies. Herein, an up to date status of the role of immune cells during the different phases of bone healing is presented. Additionally, the known and yet to know events about immune cell interactions with MSCs and osteoblasts and osteoclasts and the therapeutic implications are being discussed
Progenitor and stem cells for bone and cartilage regeneration
Research in regenerative medicine is developing at a significantly quick pace. Cell-based bone and
cartilage replacement is an evolving therapy aiming at the treatment of patients who suffer from
limb amputation, damaged tissues and various bone and cartilage-related disorders. Stem cells are
undifferentiated cells with the capability to regenerate into one or more committed cell lineages.
Stem cells isolated from multiple sources have been finding widespread use to advance the field of
tissue repair. The present review gives a comprehensive overview of the developments in stem cells
originating from different tissues and suggests future prospects for functional bone and cartilage
tissue regeneration.The European Network of Excellence EXPERTISSUES (Project No. NMP3-CT-2004-500283), under which this work was carried out, is acknowledged
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