Shape Of Scaffold Research Articles

A novel collagen scaffold supports human osteogenesis—applications for bone tissue engineering

Collagen glycosaminoglycan (CG) scaffolds have been clinically approved as an application for skin regeneration. The goal of this study has been to examine whether a CG scaffold is a suitable biomaterial for generating human bone tissue. Specifically, we have asked the following questions: (1) can the scaffold support human osteoblast growth and differentiation and (2) how might recombinant human transforming growth factor-beta (TGF-beta(1)) enhance long-term in vitro bone formation? We show human osteoblast attachment, infiltration and uniform distribution throughout the construct, reaching the centre within 14 days of seeding. We have identified the fully differentiated osteoblast phenotype categorised by the temporal expression of alkaline phosphatase, collagen type 1, osteonectin, bone sialo protein, biglycan and osteocalcin. Mineralised bone formation has been identified at 35 days post-seeding by using von Kossa and Alizarin S Red staining. Both gene expression and mineral staining suggest the benefit of introducing an initial high treatment of TGF-beta(1) (10 ng/ml) followed by a low continuous treatment (0.2 ng/ml) to enhance human osteogenesis on the scaffold. Osteogenesis coincides with a reduction in scaffold size and shape (up to 70% that of original). A notable finding is core degradation at the centre of the tissue-engineered construct after 49 days of culture. This is not observed at earlier time points. Therefore, a maximum of 35 days in culture is appropriate for in vitro studies of these scaffolds. We conclude that the CG scaffold shows excellent potential as a biomaterial for human bone tissue engineering.

Differential Effect of Scaffold Shape on Dentin Regeneration

The effect of scaffold shape on dentin regeneration is not well understood. In this study, porous hydroxyapatite/beta-tricalcium phosphate (HAp/beta-TCP), powdered HAp/beta-TCP, and polyglycolic acid (PGA) fiber mesh were used as scaffolds and transplanted with cultured porcine dental pulp-derived cells into the backs of nude mice. Samples were harvested after 6 weeks. Newly-formed hard tissue was observed in all transplants. When porous HAp/beta-TCP was used, dentin-like hard tissue was observed on the inner wall with minimum cell inclusions and odontoblast-like cells were aligned adjacent to the hard tissue. When HAp/beta-TCP powders or PGA were used, bone-like hard tissues showed cell inclusions and cell alignment was not observed. Hard tissue from the HAp/beta-TCP block group was positive for type I collagen, osteonectin, bone sialoprotein and dentin sialoprotein (DSP), which are markers for dentin. This result was confirmed by in situ hybridization with a dsp probe. Only the aligned cells were positive with an antisense probe. On the other hand, hard tissue from other scaffolds showed incomplete expression of both bone and dentin markers and they were negative for osteonectin and DSP. These results suggest that scaffold shape affects the type of tissue regenerated by dental pulp-derived cells.

Nesting complexation of C60 with large, rigid D2 symmetrical macrocycles

A series of four chiral D(2) symmetrical macrocycles, in which two 3,3'-disubstituted Binol units are bridged by conjugated organic spacers of differing lengths and/or electronic properties, have been synthesized and characterized. The four different bridges consist of either ether or ester linkages in combination with either short biphenyl spacers or long diethynylphenyl spacers. NMR, CD spectroscopy, and molecular modeling help rationalize the shape of the cyclic scaffolds and even subtle modifications in the bridging units lead to drastic changes in conformation. The three macrocycles with longer bridging units and/or ester linkages form stable 1 : 1 complexes with C(60) in toluene. The one with a short spacer and ether linkage does not. The binding constants have been determined with a high degree of accuracy via equilibrium-restricted factor analysis; with long spacers and ester linkages log K(a) = 4.37(2); with short spacers and ester linkages log K(a) = 3.498(4); with long spacers and ether linkages log K(a) = 3.509(2).

Cell culture in vivo by means of diffusion chamber system

In a diffusion chamber (DC) system, cells are cultured in vivo - hence making it possible to minimize infection and foreign material contamination. In view of this merit, we devised a technique to combine a DC system and a scaffold to the end of incubating sufficient host cells for grafting. In the present study, PLGA sponge and rat bone marrow cells were encapsulated inside a DC and then placed inside the abdominal cavities of rats. DCs were removed at two or four weeks after grafting. At four weeks after grafting, fibrous and calcified tissue matching the shape of the PLGA sponge was formed. These results suggested that the PLGA sponge was an effective scaffolding material in inducing three-dimensional tissue formation and that combination with a DC system resulted in a cell mass matching the scaffold shape. In addition, the cells were cultured in vivo - which meant that DC culturing did not require special incubation facilities or technologies after grafting.

Design and manufacture of microporous polymeric materials with hierarchal complex structure for biomedical application

Porous biodegradable polymeric scaffolds are essential for tissue engineering application since they should provide the adequate three-dimensional structure for cellular attachment and tissue development. In particular, pore size and shape and overall porosity are key structural features in controlling neotissue formation. Since scaffolds structural properties play a relevant role in all processes involved in tissue genesis including cell adhesion, migration, proliferation, growth, differentiation and biosynthesis, an accurate control over the pore size and its distribution, pore shape, pore interconnectivity, and overall porosity of scaffolds is mandatory for the success of any tissue engineering approach. Several methods have been proposed to tailor make porous scaffolds to obtain the desired pore structure. Here, three techniques to emboss a controlled pattern of porosity in biodegradable polymers, particulate leaching, phase separation and gas foaming along with their combinations, are critically reviewed highlighting process–structure–property relationship.

Potential Effect of Geometry on Wall Shear Stress Distribution Across Scaffold Surfaces

Bioreactors are used as cell culture systems for growth and maintenance of tissue-engineered scaffolds that serve as three-dimensional (3D) templates for initial cell attachment and subsequent tissue formation. The bioreactors' fluid dynamic environment is known to play a crucial role in the synthesis of cellular components via flow-mediated mechanical stimuli. Computational fluid dynamics (CFD) models in the slow turning lateral vessel (STLV Synthecon, Inc.) were simulated under Couette flow conditions. Systematic research of the wall shear stress (WSS) effects on the scaffold's geometry has been limited. Therefore, direct qualitative and quantitative correlations for WSS values were performed by analyzing and comparing WSS value distributions of two scaffold shapes. Under experimental flow conditions, the disc and prolate spheroid shapes exhibited dissimilar WSS distribution. Nonetheless, when compared to the disc models, the high pressure stagnation region of the spheroid was reduced between 60% and 95%. In the spheroid shape, approximately 40% increase in the shear stress surface exposure to flow ranged from 2 to 3 dyn/cm(2). These values suggest that WSSs are likely affected by scaffold shape and vary little with location within the Synthecon STLV. The proposed simulation studies evidenced the CFD model's flexibility to characterize and quantify forces affecting tissue-engineered scaffold design.

Changing the shape of Tröger’s base

The first synthesis of Tröger’s base analogues bearing three and four atoms in the apical strap is reported, leading to a dramatic change in the shape of the aromatic scaffold with respect to the Tröger’s base framework.

Precultivation of Engineered Human Nasal Cartilage Enhances the Mechanical Properties Relevant for Use in Facial Reconstructive Surgery

To investigate if precultivation of human engineered nasal cartilage grafts of clinically relevant size would increase the suture retention strength at implantation and the tensile and bending stiffness 2 weeks after implantation. SUMMARY BACKGROUND INFORMATION: To be used for reconstruction of nasal cartilage defects, engineered grafts need to be reliably sutured at implantation and resist to bending/tension forces about 2 weeks after surgery, when fixation is typically removed. Nasal septum chondrocytes from 4 donors were expanded for 2 passages and statically loaded on 15 x 5 x 2-mm size nonwoven meshes of esterified hyaluronan (Hyaff-11). Constructs were implanted for 2 weeks in nude mice between muscle fascia and subcutaneous tissue either directly after cell seeding or after 2 or 4 weeks of preculture in chondrogenic medium. Engineered tissues and native nasal cartilage were assessed histologically, biochemically, and biomechanically. Engineered constructs reproducibly developed with culture time into cartilaginous tissues with increasing content of glycosaminoglycans and collagen type II. Suture retention strength was significantly higher (3.6 +/- 2.2-fold) in 2-week precultured constructs than in freshly seeded meshes. Following in vivo implantation, tissues further developed and maintained the original scaffold size and shape. The bending stiffness was significantly higher (1.8 +/- 0.8-fold) if constructs were precultured for 2 weeks than if they were directly implanted, whereas tensile stiffness was close to native cartilage in all groups. In our experimental setup, preculture for 2 weeks was necessary to engineer nasal cartilage grafts with enhanced mechanical properties relevant for clinical use in facial reconstructive surgery.

Hematopoietic Microenvironment Regeneration Using Adipose-Derived Stem Cells.

Backgrounds: We have studied hematopoietic microenvironment regeneration using adipose-derived stem cells (ASCs) harvested from mice. We showed that not only bone matrix but also bone marrow could be regenerated subcutaneously, in vivo. Transplanted ASCs proliferated and differentiated into osteoblasts in micropores on the surface of scaffolds made of hydroxyapatites (HA). We could regenerate a subcutaneous microenvironment in which hematopoietic cells survived, which may lead to new treatments for fibrotic bone marrow diseases, such as idiopathic myelofibrosis and osteopetrosis.Objective: In this report, we examined the optimal shapes of scaffolds for bone and hematopoietic microenvironment regeneration using ASCs.Methods: Taking advantage of homogeneously marked cells from green fluorescent protein (GFP) transgenic mice, ASCs were isolated from the inguinal fat pads of GFP transgenic mice. ASCs were cultured in vitro and after three passages were seeded into the small pores of scaffolds of various shapes made of HA. The ASC-containing scaffolds were subsequently implanted into isogenic mice subcutaneously. Two months later, the scaffolds were extirpated for histological, immunohistochemical and flow cytometry analyses.Results: Histological examination showed that the pores were filled with bone matrix and that the bone marrow was composed of adipocytes, hematopoietic cells, and vasculatures. Bone marrow regeneration on small, thin scaffolds of high porosity was better than on other scaffolds. Immunohistochemical analysis confirmed that the GFP+ ASCs that had differentiated into osteoblasts were composed of bone matrix. Flow cytometry analyses showed that the bone marrow was composed of blood cells, including populations of monocytes, lymphocytes and granulocytes.Conclusions: Hematopoietic microenvironment engineering has great potential for hematopoietic disease therapy. The regeneration of the hematopoietic system using ASCs might be useful in the future for treating hematopoietic stem cell diseases such as leukemia as well as fibrotic bone marrow diseases.

Fabrication and Characterization of Poly(Propylene Fumarate) Scaffolds with Controlled Pore Structures Using 3-Dimensional Printing and Injection Molding

Poly(propylene fumarate) (PPF) is an injectable, biodegradable polymer that has been used for fabricating preformed scaffolds in tissue engineering applications because of in situ crosslinking characteristics. Aiming for understanding the effects of pore structure parameters on bone tissue ingrowth, 3-dimensional (3D) PPF scaffolds with controlled pore architecture have been produced in this study from computer-aided design (CAD) models. We have created original scaffold models with 3 pore sizes (300, 600, and 900 microm) and randomly closed 0%, 10%, 20%, or 30% of total pores from the original models in 3 planes. PPF scaffolds were fabricated by a series steps involving 3D printing of support/build constructs, dissolving build materials, injecting PPF, and dissolving support materials. To investigate the effects of controlled pore size and interconnectivity on scaffolds, we compared the porosities between the models and PPF scaffolds fabricated thereby, examined pore morphologies in surface and cross-section using scanning electron microscopy, and measured permeability using the falling head conductivity test. The thermal properties of the resulting scaffolds as well as uncrosslinked PPF were determined by differential scanning calorimetry and thermogravimetric analysis. Average pore sizes and pore shapes of PPF scaffolds with 600- and 900-microm pores were similar to those of CAD models, but they depended on directions in those with 300-microm pores. Porosity and permeability of PPF scaffolds decreased as the number of closed pores in original models increased, particularly when the pore size was 300 microm as the result of low porosity and pore occlusion. These results show that 3D printing and injection molding technique can be applied to crosslinkable polymers to fabricate 3D porous scaffolds with controlled pore structures, porosity, and permeability using their CAD models.

Dynamic mechanical properties of 3D fiber‐deposited PEOT/PBT scaffolds: An experimental and numerical analysis

Mechanical properties of three-dimensional (3D) scaffolds can be appropriately modulated through novel fabrication techniques like 3D fiber deposition (3DF), by varying scaffold's pore size and shape. Dynamic stiffness, in particular, can be considered as an important property to optimize the scaffold structure for its ultimate in vivo application to regenerate a natural tissue. Experimental data from dynamic mechanical analysis (DMA) reveal a dependence of the dynamic stiffness of the scaffold on the intrinsic mechanical and physicochemical properties of the material used, and on the overall porosity and architecture of the construct. The aim of this study was to assess the relationship between the aforementioned parameters, through a mathematical model, which was derived from the experimental mechanical data. As an example of how mechanical properties can be tailored to match the natural tissue to be replaced, articular bovine cartilage and porcine knee meniscus cartilage dynamic stiffness were measured and related to the modeled 3DF scaffolds dynamic stiffness. The dynamic stiffness of 3DF scaffolds from poly(ethylene oxide terephthalate)-poly(butylene terephthalate) (PEOT/PBT) copolymers was measured with DMA. With increasing porosity, the dynamic stiffness was found to decrease in an exponential manner. The influence of the scaffold architecture (or pore shape) and of the molecular network properties of the copolymers was expressed as a scaffold characteristic coefficient alpha, which modulates the porosity effect. This model was validated through an FEA numerical simulation performed on the structures that were experimentally tested. The relative deviation between the experimental and the finite element model was less than 15% for all of the constructs with a dynamic stiffness higher than 1 MPa. Therefore, we conclude that the mathematical model introduced can be used to predict the dynamic stiffness of a porous PEOT/PBT scaffold, and to choose the biomechanically optimal structure for tissue engineering applications.

Regeneration of whole meniscus using meniscal cells and polymer scaffolds in a rabbit total meniscectomy model

The current treatments of meniscal lesion in knee joint are not perfect to prevent adverse effects of meniscus injury. Tissue engineering of meniscus using meniscal cells and polymer scaffolds could be an alternative option to treat meniscus injury. This study reports on the regeneration of whole medial meniscus in a rabbit total meniscectomy model using the tissue engineering technique. Biodegradable scaffolds in a meniscal shape were fabricated from polyglycolic acid (PGA) fiber meshes that were mechanically reinforced by bonding PGA fibers at cross points with 75:25 poly(lactic-co-glycolic acid). The compressive modulus of the bonded PGA scaffold was 28-fold higher than that of nonbonded scaffold. Allogeneic meniscal cells were isolated from rabbit meniscus biopsy and cultured in vitro. The expanded meniscal cells were seeded onto the polymer scaffolds, cultured in vitro for 1 week, and transplanted to rabbit knee joints from which medial menisci were removed. Ten or 36 weeks after transplantation, the implants formed neomenisci with the original scaffold shape maintained approximately. Hematoxylin and eosin staining of the sections of the neomenisci at 6 and 10 weeks revealed the regeneration of fibrocartilage. Safranin-O staining showed that abundant proteoglycan was present in the neomenisci at 10 weeks. Masson's trichrome staining indicated the presence of collagen. Immunohistochemical analysis showed that the presence of type I and II collagen in neomenisci at 10 weeks was similar to that of normal meniscal tissue. Biochemical and biomechanical analyses of the tissue-engineered menisci at 36 weeks were performed to determine the quality of the tissue-engineered menisci. Tissue-engineered meniscus showed differences in collagen content and aggregate modulus in comparison with native meniscus. This study demonstrates, for the first time, the feasibility of regenerating whole meniscal cartilage in a rabbit total meniscectomy model using the tissue engineering method.

Bone regeneration on computer-designed nano-fibrous scaffolds

The ability to control architectural features in tissue engineering scaffolds is critical to the success of neo-tissue regeneration. In this work, reverse solid freeform fabrication and thermal phase separation of poly( l-lactic acid) (PLLA) solutions were used to create three-dimensional nano-fibrous (NF) scaffolds with complex geometries on the macro- and micro-scales. This approach allows for the fabrication of NF matrices while having precise control of internal pore size and structure, as well as external scaffold shape including architectures generated from computed-tomography scans and histological sections. In vitro cell cultivation experiments with MC3T3-E1 preosteoblasts were performed on NF scaffolds and on similarly designed solid-walled (SW) scaffolds that did not have nano-fibers. Proliferation studies showed significantly more cells on NF scaffolds after 7 d. In differentiation studies, the NF scaffolds displayed more uniform matrix and mineral production throughout. Real-time PCR also showed significantly higher expression of osteocalcin and bone sialoprotein mRNAs after 2 and 6 weeks in the NF scaffolds. Expression of type I collagen mRNA was lower in NF scaffolds which possibly indicates quicker differentiation on the NF substrate. In summary, we controlled the geometry of NF PLLA scaffolds at multiple size scales, and the in vitro results showed that these NF scaffolds were advantageous to control scaffolds for bone tissue engineering.

Regeneration of whole meniscus using meniscal cells and polymer scaffolds in a rabbit total meniscectomy model

The current treatments of meniscal lesion in knee joint are not perfect to prevent adverse effects of meniscus injury. Tissue engineering of meniscus using meniscal cells and polymer scaffolds could be an alternative option to treat meniscus injury. This study reports on the regeneration of whole medial meniscus in a rabbit total meniscectomy model using the tissue engineering technique. Biodegradable scaffolds in a meniscal shape were fabricated from polyglycolic acid (PGA) fiber meshes that were mechanically reinforced by bonding PGA fibers at cross points with 75:25 poly(lactic-co-glycolic acid). The compressive modulus of the bonded PGA scaffold was 28-fold higher than that of nonbonded scaffold. Allogeneic meniscal cells were isolated from rabbit meniscus biopsy and cultured in vitro. The expanded meniscal cells were seeded onto the polymer scaffolds, cultured in vitro for 1 week, and transplanted to rabbit knee joints from which medial menisci were removed. Ten or 36 weeks after transplantation, the implants formed neomenisci with the original scaffold shape maintained approximately. Hematoxylin and eosin staining of the sections of the neomenisci at 6 and 10 weeks revealed the regeneration of fibrocartilage. Safranin-O staining showed that abundant proteoglycan was present in the neomenisci at 10 weeks. Masson's trichrome staining indicated the presence of collagen. Immunohistochemical analysis showed that the presence of type I and II collagen in neomenisci at 10 weeks was similar to that of normal meniscal tissue. Biochemical and biomechanical analyses of the tissue-engineered menisci at 36 weeks were performed to determine the quality of the tissue-engineered menisci. Tissue-engineered meniscus showed differences in collagen content and aggregate modulus in comparison with native meniscus. This study demonstrates, for the first time, the feasibility of regenerating whole meniscal cartilage in a rabbit total meniscectomy model using the tissue engineering method.

Microspheres leaching for scaffold porosity control

Scaffold morphology plays a key role in the development of tissue engineering constructs. The control of pore size, shape and interconnection is needed to achieve adequate nutrient transport and cell ingrowth. Several techniques are available for scaffold manufacturing, but none allows easy control of morphology and is, at the same time, applicable to a wide variety of materials. To investigate the possibility of processing a wide range polymers by solvent casting/particulate leaching with accurate control of scaffold morphology, three different porogens (gelatin microspheres, paraffin microspheres and sodium chloride crystals) were used to fabricate scaffolds from commonly employed biodegradable polymers. The outcome of processing was evaluated in terms of scaffold morphology and structure/properties relationships. Highly porous scaffolds were obtained with all porogens and well defined spherical pores resulted from microspheres leaching. Furthermore, scaffolds with spherical pores showed better mechanical performance and lower flow resistance. Cytocompatibility tests performed showed no evidence of processing residuals released from the scaffolds. Solvent casting/microspheres leaching, particularly gelatin microspheres leaching, can be used to process a large number of polymers and enables to tailor scaffold pore size, shape and interconnection, thus providing a powerful tool for material selection and optimization of scaffold morphology.

Regeneration of Hematopoietic Microenvironment (Bone Marrow) Using Adipose-Derived Stem Cells - The 2nd Report.

Backgrounds: We have reported bone marrow regeneration using adipose-derived stem cells (ASCs) since 2003. In our study using mice, we showed that not only bone matrix but also bone marrow could be regenerated subcutaneously in vivo. Transplanted ASCs proliferated and differentiated into osteoblasts in micropores on the surface of scaffolds made of hydroxyapatites (HA). We have not yet obtained incontrovertible proof that the ASCs differentiated into hematopoietic cells. However, we could regenerate a subcutaneous microenvironment in which hematopoietic cells survived, which may lead to new treatments for fibrotic bone marrow diseases, such as idiopathic myelofibrosis and osteopetrosis.Purposes: In this report, we examined the optimal shapes of scaffolds for bone and bone marrow regeneration using ASCs.Methods: Taking advantage of homogeneously marked cells from green fluorescent protein (GFP) transgenic mice, ASCs were isolated from the inguinal fat pads of GFP transgenic mice. ASCs were cultured in vitro and after three passages were seeded into the small pores of scaffolds of various shapes made of HA. The ASC-containing scaffolds were then subsequently implanted into immunocompetent mice subcutaneously. Two months later, the scaffolds were extirpated for histological, immunohistochemical and flow cytometry analyses.Results: Histological examination showed that the pores were filled with bone matrix and that the bone marrow was composed of adipocytes, hematopoietic cells, and vasculatures. Bone marrow regeneration on small, thin scaffolds of high porosity was better than on other scaffolds. Immunohistochemical analysis confirmed that the GFP+ ASCs that had differentiated into osteoblasts were composed of bone matrix. Flow cytometry analyses showed that the bone marrow was composed of blood cells, including populations of monocytes, lymphocytes and granulocytes.Conclusions: Bone marrow engineering has great potential for hematopoietic disease therapy. The regeneration of the hematopoietic system using ASCs might be useful in the future for treating hematopoietic stem cell diseases such as leukemia as well as fibrotic bone marrow diseases. We plan to continue looking for suitable scaffolds and methods for bone and bone marrow regeneration using ASCs.

Fabrication and characterization of three-dimensional poly(ether-ether-ketone)/-hydroxyapatite biocomposite scaffolds using laser sintering

The ability to have precise control over porosity, scaffold shape, and internal pore architecture is critical in tissue engineering. For anchorage-dependent cells, the presence of three-dimensional scaffolds with interconnected pore networks is crucial to aid in the proliferation and reorganization of cells. This research explored the potential of rapid prototyping techniques such as selective laser sintering to fabricate solvent-free porous composite polymeric scaffolds comprising of different blends of poly(ether-ether-ketone) (PEEK) and hydroxyapatite (HA). The architecture of the scaffolds was created with a scaffold library of cellular units and a corresponding algorithm to generate the structure. Test specimens were produced and characterized by varying the weight percentage, starting with 10 wt% HA to 40 wt% HA, of physically mixed PEEK-HA powder blends. Characterization analyses including porosity, microstructure, composition of the scaffolds, bioactivity, and in vitro cell viability of the scaffolds were conducted. The results obtained showed a promising approach in fabricating scaffolds which can produce controlled microarchitecture and higher consistency.

Free-form fabrication and micro-CT characterization of poly-/spl epsiv/-caprolactone tissue scaffolds

One of the dominant approaches to tissue engineering is the seeding of biodegradable, biocompatible polymer scaffolds with progenitor cells prior to three-dimensional (3-D) culture or implantation. While the macroarchitecture of these scaffolds is important for anatomic fit, the microarchitecture has direct effects upon the ability of cells to attach, migrate, and thrive. Free-form fabrication - specifically, fused deposition - allows for simultaneous control of scaffold shape and microarchitectural characteristics. Microtomographic (micro-CT) scanners enable high-speed 3-D characterization of the salient features of these polymer scaffolds. A micro-CT scan followed by a 3-D reconstruction of serial image sections can determine porosity, pore size, pore interconnectivity, strut size, and 3-D microarchitecture. In this study, a number of polymer samples with different microarchitectures were manufactured through fused deposition free-form fabrication and subsequently characterized through micro-CT analysis. A desktop micro-CT scanner was used to examine each sample at approximately 19.1 μm resolution. Three-dimensional reconstruction and an analysis of core regions of each sample were performed. The results indicate that scaffolds of a specific shape may be constructed with interconnected pores of desired size.

Marrow-derived osteoblasts seeded into porous natural coral to prefabricate a vascularised bone graft in the shape of a human mandibular ramus: experimental study in rabbits

To find out if it was possible to prefabricate bone graft in the shape of a human mandibular ramus that possessed a pedicle that carried blood. The pore size of the natural coral was about 200 microm with a porosity of about 36%. The natural coral was made into the shape of a human mandibular ramus. Marrow-derived osteoblasts were seeded into porous natural coral scaffolds in a density of 2 x 10(8)/mL in 300 microL cell suspension. After two days of in vitro incubation, five cell-coral complexes were implanted into cell donor rabbits under the inferior epigastric blood vessels to prefabricate a vascularised bone graft of specific shape. Two months later the bone formation was observed by gross inspection and histological examination. Two months after operation, a well-vascularised bone graft in the shape of the initial coral scaffold and with a blood-carrying pedicle had been regenerated successfully. Osteogenesis followed the pattern of endochondral bone formation. New bone could be seen on the surface and in the pores of coral on histological examination. We have shown that it is possible to fabricate vascularised bone graft in a predetermined shape using tissue engineering. This kind of bone graft may have future clinical application.

In vivo bone tissue engineering using mesenchymal stem cells on a novel electrospun nanofibrous scaffold.

The objective of this study was to assess bone formation from mesenchymal stem cells (MSCs) on a novel nanofibrous scaffold in a rat model. A highly porous, degradable poly(epsilon-caprolactone) (PCL) scaffold with an extracellular matrix-like topography was produced by electrostatic fiber spinning. MSCs derived from the bone marrow of neonatal rats were cultured, expanded, and seeded on the scaffolds. The cell-polymer constructs were cultured with osteogenic supplements in a rotating bioreactor for 4 weeks, and subsequently implanted in the omenta of rats for 4 weeks. The constructs were explanted and characterized by histology, immunohistochemistry, and scanning electron microscopy. The constructs maintained the size and shape of the original scaffolds. Morphologically, the constructs were rigid and had a bone-like appearance. Cells and extracellular matrix (ECM) formation were observed throughout the constructs. In addition, mineralization and type I collagen were also detected. This study establishes the ability to develop bone grafts on electrospun nanofibrous scaffolds in a well-vascularized site using MSCs.