Papers by Keyword: Osteogenesis

Abstract: To evaluate the osteoconductive potential of connected porous hydroxyapatite (HAp), we histologically analyzed the newly formed bone inside unidirectional porous HAp (Regenos^®, Kuraray, Japan; 75% porosity, n=17) and interconnected porous HAp (Neobone^®, Covalent Materials, Japan; 75% porosity, n=10) 26 weeks after their implantation as bone spacers between the split lumbar laminae of goats. As a control, non-connected porous HAp spacers (Apaceram^®, Pentax, Japan; 50% porosity, n=5) were used. After staining non-decalcified samples with Villanueva Goldner, changes in pore shape were evaluated microscopically and new bone formation in HAp spacers was quantitatively analyzed. In addition, blood vessel distribution was evaluated by hematoxylin and eosin staining. Changes in pore shape were observed in 76% of the Regenos^® spacers and 90% of the Neobone^® spacers but were not detected in the Apaceram^® spacers. Only limited new bone formation was observed in the Regenos^® and Neobone^® spacers, whereas vascular-like structures were detected in 82% of the Regenos^®, 70% of the Neobone^®, and 80% of the Apaceram^® spacers. The changes in pore shape were thought to have resulted from the low initial compression strength of the connected porous HAp, which may have limited the inherent osteoconductive potential of connected HAp. Our findings suggest that the maintenance of pore shape is required for promoting new bone formation in connected porous HAp when used as lamina spacers in spinal surgery.

Abstract: Osteogenic differentiation of mesenchymal stem cells (MSC) is important in the field of bone tissue engineering. The identification of biological factors that influence osteogenesis is vital for developing a broader understanding of how complex microenvironments play a role in differentiation. The aim of this study was to demonstrate that adipose-derived stem cell (ADSC) osteogenesis is enhanced through interaction with extracellular matrices (ECM) secreted by ADSC undergoing osteogenesis. ADSC were obtained from human patients following elective abdominoplasty. Cells were selected for plastic adherence, characterized, and induced to differentiate using osteogenic supplements (OS; dexamethasone, ascorbic acid, and beta-glycerol phosphate). Cells were removed at several time points during osteogenesis and the secreted ECM was isolated. Undifferentiated cells were re-seeded onto the cell secreted ECMs and induced to differentiate with OS. At several time points, cells cultured on ECMs or tissue culture plastic controls (i.e. uncoated surface) were collected and RNA isolated. QPCR and gene array analysis revealed enrichment of osteogenic markers and more rapid progression through osteogenic maturational phases in cells seeded onto ECM secreted at the midpoint in differentiation (ca. 15 days). Our results demonstrate that the cumulative deposition of ECM reaches a critical point at approximately 15 days, before which there appear to be no definitive osteogenic cues from the matrix, and after which, strong drivers of osteogenesis are present. The creation of microenvironments that contain essential morphogenic matrix signals is an important step towards methods of growing and differentiating MSC in a rapid effective manner, particularly for bone-related clinical applications.

Abstract: Aseptic loosening induced by wear debris particles of artificial joint is characterized by a considerable suppression of osteogenesis. The objective of this investigation was to determine the effect of different-sized titanium particle on protein synthesis, and mineralization in bone marrow–derived mesenchymal stem cells(BMSCs) induced toward osteogenic differentiation in vitro. Rat bone marrow–derived mesenchymal stem cells (rBMSCs) induced toward osteogenesis were cultured in the presence or absence of titanium particles in varied size, 0.9µm, 2.7µm, 6.9µm, respectively. Flow cytometry characterization of rBMSCs proved 99% homogeneity by using with cell-surface antibody. The bone matrix protein synthesis evaluation showed that three size groups of titanium particles could suppress early, middle, and late markers of the osteogenic lineage, i.e., alkaline phosphatase activity, C-terminal type I procollagen and osteocalcin secretion repectively, in a dose- and time-dependent manner. The least detrimental particle size group was 0.9 μm, which is a reasonable finding as this group is more susceptible to phagocytosis due to smaller size. The cell-mediated matrix mineralization in terminally differentiated cultures by Alizarin Red S assay revealed a reduction in the number and area of mineralizing nodules, even mineralization calcium concentration in BMSCs cultures after titanium particles treatment. Collectively, the data suggest that different size titanium particles alters osteogenic differentiation in BMSCs cultures during lineage progression and provide further insight into wear debris-induced reduced bone formation.

Abstract: An ideal bone graft material should have osteocondutive, osteroindurctive, and osteogenic features. Scientists and doctors have been trying to develop this kind of material for over one century. However, all the features of few materials used in clinic now have been qualified. Recently, COLLOSS, as the new generation bone graft material of demineralized bone matrix, almost achieved this height. The paper presents a general survey of COLLOSS including its extraction processes, biological characteristics, and application prospects.

Abstract: Bone exhibits hierarchical levels of organization from macroscopic to microscopic to nanoscale. The objective of this work was to develop a bonemimetic composite matrix to provide structural support to the regenerating region and to support the cascade of osteogenic differentiation of progenitor marrow stromal (BMS) cells. Sheets of poly(L-lactide) (L-PLA) nanofibers, fabricated by electrospinning, were coated with a hydrogel/apatite precursor solution, stacked and pressed together, and allowed to crosslink by photopolymerization to form a peptide-reinforced hydrogel/apatite laminated composite. Addition of an osteonectin-derived glutamic acid peptide (Glu6) and lamination resulted in an order of magnitude increase in modulus of the composite to within the range reported for wet human cancellous bone. Lamination significantly increased the extent of mineralization of BMS cells and the laminates reinforced with apatite nanocrystals and conjugated with integrin-binding focal-point adhesion RGD peptide (Lam-RGD-HA) had 3-fold higher calcium content and higher expression of osteogenic markers osteopontin and osteocalcin (compared to laminates without apatite or RGD) after 21 days of incubation in osteogenic media. Laminated osteon-mimetic structures have the potential to provide mechanical strength to the regenerating region as well as supporting the differentiation of progenitor cells to the osteogenic lineage.

Abstract: An hydrated putty was prepared by mixing submicron particles, rounded particles and granules of Biphasic Calcium Phosphate (BCP) ceramics composed of HA and β-TCP phases. The material filled entirely critical sized defects in the femoral epiphysis of NZW rabbits. After 3, 6 and 12 weeks, histology revealed that submicron particles were rapidly degraded by multinucleated TRAP-positive cells. This osteoclastic resorption stimulated bone ingrowth while the large BCP particles served as scaffold supporting bone healing by osteoconduction.

Abstract: Unidirectional porous hydroxyapatite (UDPHAp) was developed which has microstructure in that cross sectionally oval pores 100 ~ 300µm in diameter penetrate through the material, and that is suitable for osteogenesis and angiogenesis.The porosity of the UDPHAp was 75 % and the compression strength was 14 MPa. A cortical bone defect was made at proximal tibia of Japanese white rabbit, and a trapezoidal prisms shaped UDPHAp was implanted. By histlogical evaluation, 2 weeks after implantation, new bone and new capillary was observed inside UDPHAp. Twelve weeks after implantation, new bone formation was observed in 41.6 % of the porous area. The results of this study suggest a great possibility of utilizing it in actual clinical setting as a bone substitution.

Abstract: Degenerative disc disease has been implicated as a major component of spine pathology. However, though biological repair of the degenerate disc would be the ideal treatment, there is a lack of a universally accepted scaffold for tissue engineering of intervertebral discs (IVD) and little is known of how to differentiate mesenchymal stem cells (MSCs) to a disc-like phenotype. We show that 2.5% Protasan® UP G213 cross-linked to 5% genipin might be a promising scaffold for disc tissue engineering. Furthermore, we have developed extremely N-rich plasma polymer layers, which we call "PPE:N" (N-doped plasma-polymerized ethylene, containing up to 36% [N]). We show that PPE:N almost completely suppresses the expression not only of type X collagen, but also of osteogenic marker genes such as alkaline phosphatase (ALP), bone sialoprotein (BSP) and osteocalcin (OC). In contrast, neither aggrecan nor types 1 collagen expression were significantly affected. These results indicate that PPE:N coatings may be suitable surfaces for inducing MSCs to a chondrocyte or disc-like phenotype for tissue engineering of cartilage or IVDs, in which hypertrophy and osteogenesis are suppressed.

Abstract: Porous calcium phosphate cement (CPC) scaffolds were successfully fabricated utilizing particle-leaching method. Mesenchymal stem cells (MSCs) were cultured, expanded and seeded on the scaffolds and the proliferation and differentiation of MSCs into osteoblastic phenotype were determined using MTT assay, ALP activity and ESEM. The results revealed that the CPC scaffolds were biocompatible and had no negative effects on the MSCs in vitro. The in vivo biocompatibility and osteogenicity of the scaffolds were investigated. Both pure scaffolds and MSCs/scaffold constructs were implanted in rabbit mandibles and studied histologically. The results showed that CPC scaffolds exhibited good biocompatibility and osteoconductivity. Moreover, the introduction of MSCs into the scaffolds dramatically enhanced the efficiency of new bone formation initially.

Abstract: Historically the function of biomaterials has been to replace diseased, damaged and aged tissues. First generation biomaterials, including bio ceramics, were selected to be as inert as possible in order to minimize the thickness of interfacial scar tissue. Bioactive glasses provided an alternative from the 1970’s onward; second generation bioactive bonding of implants with tissues and no interfacial scar tissue. This chapter reviews the discovery that controlled release of biologically active Ca and Si ions from bioactive glasses leads to the up-regulation and activation of seven families of genes in osteoprogenitor cells that give rise to rapid bone regeneration. This finding offers the possibility of creating a new generation of gene activating bioceramics designed specially for tissue engineering and in situ regeneration of tissues.