Papers by Keyword: Tissue Engineering

Abstract: Since 2001, we have started tissue engineered approach for hard tissue repair using mesenchymal stromal cells (MSCs) derived from patient’s bone marrow. MSCs were culture expanded on culture dish, then applied on various ceramics including hydroxyapatite (HA) ceramics. The MSCs on the ceramics were further cultured in osteogenic media to induce osteognenic differentiation. The differentiation resulted in appearance of bone forming osteoblasts as well as bone matrix on the ceramics, thus we could fabricate the tissue engineered bone. We have reported that the tissue engineered bone is effective for treatment of large bone defect, which is difficult to repair only with artificial materials such as HA ceramics. The present study focused on osteogenic capability of cryopreserved human MSCs derived from patients who already were treated by the tissue engineered bone. The MSCs showed high alkaline phosphatase activity together with abundant bone matrix formation when cultured in osteogenic media. The MSCs also showed in vivo new bone formation when implanted at subcutaneous sites of athymic nude rats. Based on the results, we concluded that the tissue engineering approach is a reliable method to be used in hard tissue regeneration.

Abstract: A novel collagen sponge that can protect cell leakage during cell seeding was developed by wrapping all the surfaces except the upside of a collagen sponge with membrane that has pores smaller than cell. The collagen sponge was used for three-dimensional culture of human bone marrow-derived mesenchymal stem cells (MSCs). The cells adhered to the collagen, and proliferated to fill the spaces in the sponge. The cell seeding efficiency was higher than 95%. The MSCs cultured in the collagen sponge in the chondrogenic induction medium supplemented with TGF-β3 and BMP6 expressed genes encoding type II collagen, SOX9 and aggrecan. HE staining indicated the round morphology of differentiated cells and the extracelluler matrices were positively stained by safranin O and toluidine blue. Type II collagen and cartilage proteoglycan were detected by immunostaining with anti-type II collagen and anti-cartilage proteoglycan. These results suggest the chondrogenic differentiation of MSCs. The collagen sponge facilitated cell seeding and chondrogenic differentiation of MSCs, and will be useful for cartilage tissue engineering.

Abstract: In this study, we investigated the effect of the use of alginate sponge as a chondrocyte-3D scaffold for the construction of a cartilage graft. Alginate sponge was made by 5% alginic acid which was crosslinked by CaCl2. Chondrocytes were obtained from a nasal septum after the operation and cultured in 3D alginate sponge. For analysis of cell differentiation, we have checked aggrecan, collagen type I and II using RT-PCR and performed the histological and scanning electron microscopy analysis. Our experiments showed that alginate sponge of 5% promoted sufficient chondrocyte proliferation and differentiation, resulting in the formation of a specific cartilage matrix. The sponge presents new perspectives with respect to in vitro production of "artificial" cartilage. We conclude that the alginate sponges have potential as a scaffold for cartilage tissue engineering.

Abstract: Scaffold technology is integral in advancing tissue engineering and one of the tissues of interest here is the tendon/ligament. Advancement in the tissue engineering of tendon/ligament has become very much a materials engineering problem than ever, with the selection of appropriate biomaterial and scaffold architecture. Such is the key to successful tendon/ligament tissue regeneration construct. Popular materials used in recent years include various poly (l-lactic) biomaterials and collagen. However, shortcomings of these materials, in terms of poor mechanical strength or short degradation period, are yet overcome. Bombyx mori silk, though used in biomedical sutures for decades due to its excellent mechanical properties, has been overlooked for applications in ligament tissue engineering, only until recently. This is largely due to previous misconceptions in its biocompatibility and biodegradability characteristics. This paper describes the use of a silk-based scaffold with knitted architecture and investigates its strengths as compared to previous PLGA-based knitted scaffolds. An electrospun nanofiber surface on knitted microfiber architecture is adopted and it is found to have better composite-material integrity, in vitro degradation resistance, and encourages cell adhesion and proliferation.

Abstract: Tissue engineering (TE) aims/seeks to achieve the substitution of organ transplantation by the creation of living, functional tissues. It has been suggested that biocompatible porous materials (scaffolds) and a controllable 3D environment are required to aid in the 3D cell organisation and their development into functional tissue. Our research envisions a TE-approach towards the repair of large, load bearing defects in long bones. In vitro standardised, systematic, quantitative screening of potential bone scaffolds is required to understand how scaffolds can affect cell behaviour. This screening will avoid a trial-and-error approach and thus limit the number of animal experiments. Such a screening should be based on the knowledge of mechanical, physical and (bio)chemical scaffold properties and their interaction with cell behaviour. In addition, the design and production of a clinically relevant scaffold requires control over its mechanical behaviour and a new approach for cell seeding in a 3D scaffold, as well as providing nutrition for the engrafted cells. The objective of this research is to gain substantial knowledge about guided bone regeneration and to develop quantitative methodologies that can lead to consistent and reproducible bone regeneration.

Abstract: Despite extensive efforts in the development of fabrication methods to prepare porous ceramic scaffolds for osseous tissue regeneration, all porous materials have a fundamental limitation- the inherent lack of strength associated with porosity. Shells (nacre), tooth and bone are frequently used as examples for how nature achieves strong and tough materials made out of weak components. So, the unresolved engineering dilemma is how to create a scaffold that is both porous and strong. The objective of this study was to mimic the architecture of natural materials in order to create a new generation of strong hydroxyapatite-based porous scaffolds. The porous inorganic scaffolds were fabricated by the controlled freezing of water-based hydroxyapatite (HA) slurries. The scaffolds obtained by this process have a lamellar architecture that exhibits similarities with the meso- and micro- structure of the inorganic component of nacre. Compressive strengths of 20 MPa were measured for lamellar scaffolds with densities of 32%, significantly better than for the HA with random porosity. In addition, the lamellar materials exhibit gradual fracture unlike conventional porous HA scaffolds. These biomimetic scaffolds could be the basis for a new generation of porous and composite biomaterials.

Abstract: Three-dimensional biodegradable porous scaffolds play an important role in tissue engineering as temporary templates for transplanted cells to guide the formation of the new organs. Two kinds of novel biodegradable porous scaffolds for tissue engineering have been developed by our group by hybridizing synthetic poly(α-hydroxy acids) with naturally derived collagen. One is their hybrid sponge prepared by introducing collagen microsponges in the pores of poly(α-hydroxy acids) sponge. The other one is their hybrid mesh prepared by forming collagen microsponges in the interstices of poly(α-hydroxy acids) mesh. The hybrid scaffolds were used for three-dimensional culture of fibroblast, tenocytes, chondrocytes and mesenchymal stem cells for tissue engineering of skin, ligament, cartilage and osteochondral tissue. These cells adhered and spread well in the hybrid scaffolds, proliferated, secreted extracellular matrices and formed the respective tissues. The synthetic polymer sponge, or mesh serving as a skeleton, reinforced the hybrid scaffolds and resulted in easy handling, while the collagen microsponges provided the hybrid sacffolds with a microporous structure and hydrophilicity, and therefore, easy cell seeding. The hybrid scaffolds will be useful for tissue engineering.

Abstract: In order to realize true regenerative medicine, we have developed a novel technology for the reconstruction of tissues and organs by utilizing intelligent materials including temperature-responsive polymers. We developed temperature-responsive culture surfaces, on which temperature-responsive polymers are covalently immobilized. Cells are cultured on the surfaces at 37°C, and harvested as transplantable cell sheets by reducing temperature to 20°C. With these cell sheets we regenerate various kinds of tissues such as cornea and heart.

Abstract: Micropatterned PEGylated substrates with two-dimensional arrays of plasma-etched circular domains (diameter:100 micro-m) were prepared by coating of mercapto-functionalized poly(ethylene glycol) (PEG) on Au surface, followed by plasma-etching through a metal mask pattern with circular holes. The PEGylated region on the patterned substrate works to repel proteins, consequently, inhibits cell adhesion. Then the micro-patterning of bovine articular chondrocytes or rat primary hepatocytes hetero-spheroids underlaid with human umbilical endothelial cells (HUVEC) was achieved on the plasma-etched circular domains, exposing the base gold surface. Obtained results suggested that the efficiency of inhibiting non-specific protein adsorption significantly affects on construction of micro-patterned cell adhesion and hetero-spheroids. The formation of hetero-spheroid thus suggested is significantly modulated by suface properties, particularly non-fouling character of PEG region. These arrayed spheroids is promising materials for tissue and cell-based biosensors (TBB/CBB) as well as tissue engineering technologies.

Abstract: Nanotechnology is defined as the use of materials with at least one dimension less than 100 nm. Although nanotechnology has revolutionized many fields to date, it use in medical applications remains at it infancy. This manuscript describes recent promising studies made towards increasing tissue regeneration through the use of nano compared to conventional materials.