Comparison of Proliferation and Osteogenic Differentiation Potential of Rat Mandibular and Femoral Bone Marrow Mesenchymal Stem Cells In Vitro.

This study was conducted to compare the in vitro proliferation and osteogenic differentiation potential of mesenchymal stem cells (MSCs) derived from mandibular (M-MSCs) or femur (F-MSCs) tissues of rats. M-MSC and F-MSC cultures were isolated and established from the same rat. Cultures were observed for morphological changes by microscope and growth characteristics by CCK-8 and cloning assays. Cell adhesion ability on a culture plate and titanium sheet was detected by staining with toluidine blue and Hoechst 33258, respectively. The levels of Ca, P, and ALP (serially) during osteogenic differentiation were evaluated. Cultures were analyzed for mineralization potential with alizarin red and ALP staining methods and for differentiation markers with RT-PCR (ALP, Runx2, and OCN). M-MSCs and F-MSCs were successfully isolated from the same rat with uncontaminated culture, which showed significant differences in morphology. The proliferation rate of M-MSCs was higher than F-MSCs in primary culture, but significantly lower after passage. More colonies are formed from F-MSCs than from M-MSCs. M-MSCs showed a significantly higher mineralization and osteogenic differentiation potential, which might be of significance for use in bone/dental tissue engineering. In vitro, cell passage will decrease the proliferation ability of M-MSCs. The higher mineralization and osteogenic differentiation potential of M-MSCs could make them an approachable stem cell source for further application in stem cell-based clinical therapies.

Property of Human Bone Marrow Stromal Cells Derived From Bone Fragments Removed in Sagittal Split Ramus Osteotomy.

Bone tissue engineering is in the process of making the shift from bench to bed. Organ as a cell source is important for tissue engineering. The appropriate cells should be harvested without invasiveness and ethical problems. The authors focused on mandibular cortex bone fragments removed in sagittal split ramus osteotomy as a cell source for bone tissue engineering. These bone fragments were discarded after surgery until now. Bone marrow stromal cells (BMSCs) were harvested from inside of bone fragments, which is an endosteal region. Endosteal region is known to be a hematopoietic stem cell niche and harbors osteoblasts, preosteoblasts, and mesenchymal stem cells (MSCs). Bone marrow stromal cells could be cultured easily, and grew rapidly in vitro under ordinary serum-supplemented culture condition. The expression pattern of surface markers of BMSCs was the same as that of MSCs. Bone marrow stromal cells could differentiated into multiple mesenchymal lineages (osteoblasts, adipocytes, chondrocytes, and smooth muscle cells). These results indicated the existence of MSCs in BMSCs. The osteoblastic characters of BMSCs were examined more closely. Bone marrow stromal cells showed a high alkaline phosphatase activity, and expressed osteoblastic markers (PTHr, bone sialoprotein, Type I collagen, Rnut-related transcription factor 2, and osteocalcin). In transplantation experiments, BMSCs generated ectopic bone tissues on the border of hydroxyapatite scaffold without osteogenic differentiation-inducing agents such as dexamethasone (Dex) or bone morphogenetic protein. The results of this study suggest that mandibular cortex bone fragments removed in sagittal split ramus osteotomy are a good cell source for bone tissue engineering.

A polymerase chain reaction-based method for isolating clones from a complimentary DNA library in sheep.

The sheep (Ovis aries) is favored by many musculoskeletal tissue engineering groups as a large animal model because of its docile temperament and ease of husbandry. The size and weight of sheep are comparable to humans, which allows for the use of implants and fixation devices used in human clinical practice. The construction of a complimentary DNA (cDNA) library can capture the expression of genes in both a tissue- and time-specific manner. cDNA libraries have been a consistent source of gene discovery ever since the technology became commonplace more than three decades ago. Here, we describe the construction of a cDNA library using cells derived from sheep bones based on the pBluescript cDNA kit. Thirty clones were picked at random and sequenced. This led to the identification of a novel gene, C12orf29, which our initial experiments indicate is involved in skeletal biology. We also describe a polymerase chain reaction-based cDNA clone isolation method that allows the isolation of genes of interest from a cDNA library pool. The techniques outlined here can be applied in-house by smaller tissue engineering groups to generate tools for biomolecular research for large preclinical animal studies and highlights the power of standard cDNA library protocols to uncover novel genes.

Three-dimensional culture of mandibular human osteoblasts on a novel albumin scaffold: growth, proliferation, and differentiation potential in vitro.

PURPOSE: Bone tissue engineering is a promising approach for bone reconstruction in oral and maxillofacial surgery. The aim of this study was to investigate the microstructure and biocompatibility of a novel albumin scaffold developed from human serum on human alveolar osteoblasts. MATERIALS AND METHODS: Samples of mandibular bone were obtained during routine oral surgery. Osteoblast cells were cultured and plated in a spongy, noncalcified protein scaffold prepared with plasmatic albumin crossed with a glutaraldehyde-type agent (study group) and in a large-particle mineralized cancellous allograft (control group). Measurement of the differentiation marker alkaline phosphatase and histologic examination were performed after 30 days of incubation. The cultures were examined for cell growth patterns and morphology by scanning electron microscopy and histomorphometry. RESULTS: Cultured osteoblasts showed comparable phenotypic profiles and expressed alkaline phosphatase in albumin scaffold. Hematoxylin-eosin staining revealed a bonelike extracellular matrix in study scaffold and mineralization of osteoblasts cultured in the albumin scaffold was confirmed by von Kossa staining. CONCLUSION: Osteoblasts were able to proliferate in vitro and synthesize a bonelike extracellular matrix and mineralized tissue. The results indicate that this novel albumin scaffold is a favorable substrate for the growth and differentiation of osteoblasts and a promising material for bone tissue engineering and repair of bone defects.

In vitro osteogenic differentiation of human mesenchymal stem cells and in vivo bone formation in composite nanofiber meshes.

Tissue engineering has become an alternative method to traditional surgical treatments for the repair of bone defects, and an appropriate scaffold supporting bone formation is a key element in this approach. In the present study, nanofibrous organic and inorganic composite scaffolds containing nano-sized demineralized bone powders (DBPs) with biodegradable poly(L-lactide) (PLA) were developed using an electrospinning process for engineering bone. To assess their biocompatibility, in vitro osteogenic differentiation of human mandible-derived mesenchymal stem cells (hMSCs) cultured on PLA or PLA/DBP composite nanofiber scaffolds were examined. The mineralization of hMSCs cultured with osteogenic supplements on the PLA/DBP nanofiber scaffolds was remarkably greater than on the PLA nanofiber scaffold during the first 14 days of culture but reached the same level after 21 days. The in vivo osteoconductive effect of PLA/DBP nanofibrous scaffolds was further investigated using rats with critical-sized skull defects. Micro-computerized tomography revealed that a greater amount of newly formed bone extended across the defect area in PLA/DBP scaffolds than in the nonimplant and PLA scaffolds 12 weeks after implantation and that the defect size was almost 90% smaller. Therefore, PLA/DBP composite nanofiber scaffolds may serve as a favorable matrix for the regeneration of bone tissue.

Callus formation enhanced by BMP-7 ex vivo gene therapy during distraction osteogenesis in rats.

This study was designed to observe the effects of bone morphogenetic protein-7 (BMP-7) ex vivo gene therapy on callus formation during rat mandibular distraction osteogenesis (DO). Fifty-four Sprague-Dawley rats underwent osteodistraction of the right mandible and were then randomly divided into three groups. Immediately after distraction, autologous bone marrow mesenchymal stem cells (MSCs) transfected with BMP-7, MSCs untransfected with BMP-7, and physiological saline were injected into the distraction gaps of the mandibles in groups A, B, and C, respectively. Nine animals from each group were euthanized at 2 and 6 weeks after completion of distraction. The distracted mandibles were removed and processed for radiographic, histological, immunohistochemical, and scanning electron microscopic examinations as well as Ca/P ratio analysis. Group A animals showed greater bone formation and earlier mineralization in the distracted callus when compared with group B. Similarly increased callus formation was found in group B than group C. Positive immunostaining of BMP-7 was observed in the distracted callus in all groups. However, BMP-7 expression was much stronger in group A compared with groups B and C. The results of this study suggest that BMP-7-mediated ex vivo gene transfer based on MSCs may accelerate callus formation in distraction osteogenesis and facilitate consolidation. Local gene therapy may ultimately be an alternative or supplemental approach to DO enhancement, especially for patients whose osteogenic potentials are compromised by diseases such as osteoporosis, severe trauma, and postoncologic irradiation.

Invitro study of adherent mandibular osteoblast-like cells on carrier materials.

Augmentation of the craniofacial region is necessary for many aesthetic and reconstructive procedures. Tissue engineering offers a new option to supplement existing treatment regimens. In this procedure, materials composed of hydroxyapatite (HA), of synthetic or natural origin, are used as scaffolds. The aim of this study was to evaluate the effects of three HA materials on cultured human osteoblasts in vitro. Explant cultures of cells from human alveolar bone were established. Human osteoblasts were cultured on the surface of HA calcified from red algae (C GRAFT/Algipore), deproteinized bovine HA (Bio-Oss) and bovine HA carrying the cell binding peptide P-15 (Pep Gen P-15). Cultured cells were evaluated with respect to cell attachment, proliferation and differentiation. Cells were cultured for 6 and 21 days under osteogenic differentiation conditions, and tissue-culture polystyrene dishes were used as control. The ability of cells to proliferate and form extracellular matrix on these scaffolds was assessed by a DNA quantification assay, protein synthesis analysis and by scanning electron microscopical examination. Osteogenic differentiation was screened by the expression of alkaline phosphatase. The osteoblastic phenotype of the cells was monitored using mRNA levels of the bone-related proteins including osteocalcin, osteopontin and collagen Type I. We found that cells cultured on C GRAFT/Algipore) and Pep Gen P-15 showed a continuous increase in DNA content and protein synthesis. Cells cultured on Bio-Oss showed a decrease in DNA content from Day 6 (P < 0.05) to Day 21 (P < 0.0001) and protein synthesis on Day 21 (P < 0.005). Alkaline phosphatase activity increased in cells grown on C GRAFT/Algipore and Pep Gen P-15 in contrast to cells grown on Bio-Oss, in which the lowest levels of activity could be observed on Day 21 (P < 0.05). Reverse transcriptase polymerase chain reaction analysis confirmed the osteoblastic phenotype of the cells grown on all three materials throughout the whole culture period. The results of our in vitro study show that the differences in metabolic activity of cells grown on HA materials are directly related to the substrate on which they are grown. They confirm the excellent properties of HA carrying the cell binding peptide P-15 and HA calcified from red algae as used in maxillofacial surgery procedures.

[Pathomorphology of regenerative processes in mandibular fracture after sodium succinate treatment and laser magnetotherapy in an experimental setting]. / Morfologicheskií analiz reparativnykh protsessov v éksperimente pri sazhivlenii perelomov nizhnei cheliusti v usloviiakh primeneniia suktsinata natriia i lazeromagnitoterapii.

Morphological reactions in tissue adjacent to mandibular angular fracture were studied in guinea pigs treated with sodium succinate and laser magnetotherapy. Due to succinate therapy the exudative component of inflammation was less expressed in comparison with the control, macrophagal reaction and neoangiogenesis were activated, the volume of damaged muscle tissue and the incidence of suppurations decreased. The number of osteoblasts increased and new bone structures acquired a lamellar pattern earlier than in the control. Sodium succinate therapy in combination with laser magnetotherapy had a more pronounced positive effect as regards activation of macrophagal reaction and neoangiogenesis and a decrease in the area of fibrosclerotic changes in the zone of damaged muscles, where newly formed myosymplasts differentiated into myotubes and even in muscle fibers. Suppuration of the wound was prevented. Bone tissue in the fracture zone formed without preliminary formation of cartilaginous tissue, which resulted in more rapid osteogenesis (lamellar bone growth in the fracture zone).

Alterations in the expression of osteonectin, osteopontin and osteocalcin mRNAs during the development of skeletal tissues in vivo.

Heterogeneity in the expression of three members of non-collagenous matrix proteins in osteogenic and chondrogenic development in vivo were investigated by in situ hybridization. Sections of several skeletal tissues from mice at various stages of development were hybridized with digoxigenin-labeled complementary RNA probes encoding osteonectin (Osn), osteopontin (Osp) and osteocalcin (Osc). In calvariae and mandibulae, Osn messenger RNA (mRNA) was detected in cells in pre-osseous and osseous tissues before mineralization. Osp mRNA was found in cells attached to the mineralized bone matrix together with Osn mRNA followed by the expression Osc mRNA. In long bones, mRNAs for Osn, Osp and Osc were sequentially expressed with bone development from primary spongiosa to diaphyseal bone. In growth cartilage, Osn mRNA was observed in chondrocytes in non-mineralized cartilage, whereas Osp mRNA was detected in hypertrophic chondrocytes in mineralized cartilage matrix with a characteristic switch in expression. Osc mRNA was not detected in any chondrocytes. These results indicate that osteogenic differentiation in bone development in vivo is characterized by the sequential expression of these three genes, and suggest that these genes are expressed differentially and specifically, in association with extra-cellular matrix mineralization.

Differential response in alveolar bone osteoclasts residing at two different bone sites.

Using a histochemical method for demonstrating acid phosphatase activity, we have studied osteoclasts residing at two different bone sites in rat incisor alveolar bone, one at the endosteum and the other at the tooth socket, and compared the response of these osteoclasts to systemic changes. After 12 days of calcium (0%) or phosphorus (0.2%) deprivation, the number of osteoclasts/cross section at the endosteum increased 463% (P less than 0.001) and 103% (P less than 0.002), respectively. After 10 days of calcium or phosphorus replenishment, the number of osteoclasts at this bone site decreased to levels not significantly different from those in the control. In contrast, the number of osteoclasts at the incisor socket remained insignificantly changed throughout the experimental period. A similar osteoclast differential response was also observed in the alveolar bone surrounding the first molar tooth. After 12 days of calcium deprivation, the number of osteoclasts/mm bone surface increased 371% (P less than 0.001) at the endosteum but remained insignificantly changed at the first molar socket. These results suggest that an osteoclast differential response exists in alveolar bone and that the response may be of significance inasmuch as the major function of alveolar bone is to support the teeth. The work described here supports the concept of local as well as systemic regulation of bone metabolism to simultaneously perform the dual functions of mineral homeostasis and mechanical support.