ObjectiveTo review the development and applications of hypoxia-inducible factor 1α (HIF-1α) in the strategy of tissue engineered angiogenesis and osteogenesis. MethodThe literature about HIF-1α in tissue engineering technology was reviewed, analyzed, and summarized. ResultsHIF-1α plays a key role in angiogenic-osteogenic coupling, and as an upstream regulator, HIF-1α can regulate the expressions of its target genes related with angiogenesis and osteogenesis. In addition, HIF-1α not only can control and improve the angiogenesis, but also has important significance in proliferation and differentiation of seed cells, especially stem cells, which is the foundation for bone healing. ConclusionsWith the development of tissue engineering technology, the problems in the applications of HIF-1α, such as the effective dose of targeting controlled-release, pro-inflammatory effect, and carcinogenicity, will be explored and solved in the future, so it can be used better in clinical.
Cell sheet engineering is an important technology to harvest the cultured cells in the form of confluent monolayers using a continuous culture method and a physical approach. Avoiding the use of enzymes, expended cells can be harvested together with endogenous extracellular matrix, cell-matrix contacts, and cell-cell contacts. With high efficiency of cell loading ability and without using exogenous scaffolds, cell sheet engineering has several advantages over traditional tissue engineering methods. In this article, we give an overview on cell sheet technology about its applications in the filed of tissue regeneration, including the construction of soft tissues (corneal, mucous membrane, myocardium, blood vessel, pancreas islet, liver, bladder and skin) and hard tissues (bone, cartilage and tooth root). This techonoly is promising to provide a novel strategy for the development of tissue engineering and regenerative medicine. And further works should be carried out on the operability of this technology and its feasibility to construct thick tissues.
This study was to explore a better three-dimensional (3-D) culture method of chondrocyte. The interpenetrating network (IPN) gel beads were developed through a photo-cross linking reaction with mixed barium ions and calcium ions at the ratio of 5:5 with the methacrylic alginate (MA), which was a chemically conjugated alginate with methacrylic groups. The second generation of primary cartilage cells was encapsulated in the MA gel beads for three weeks. In the designated timing, HE stain, Alamar blue method and Scanning electron microscopic were used to determine the cartilage cells growth, proliferation and the cell distribution in the scaffolds, respectively. The expression of typeⅡcollagen was investigated by an immunohistochemistry assay and the glycosaminoglycan content was quantitatively evaluated with the spectrophotometry of 1, 9 dimethylene blue assay. Compared to the alginate control group, the deposition of glycosaminoglycan was significantly upregulated in IPN-MA gel beads with higher cell proliferation. The secretion of extracellular matrix and proliferation of chondrocyte in methacrylic alginate gel beads were higher than that in Alginate beads. Cells were able to attach, to grow well on the scaffolds under scanning electron microscopy. The result of immunohistochemistry staining of collagen typeⅡwas positive, confirming the maintenance of chondrocyte phenotype in methacrylic alginate gel beads. This study shows a great potential for three-dimensional culture of cartilage.
ObjectiveTo review the development of cell sheet engineering technology in engineering vascularized tissue. MethodsThe literature about cell sheet engineering technology and engineering vascularized tissue was reviewed, analyzed, and summarized. ResultsAlthough there are many methods to engineer vascularized tissue, cell sheet engineering technology provides a promising potential to develop a vascularized tissue. Recently, cell sheet engineering technology has become a hot topic in engineering vascularized tissue. Co-culturing endothelial cells on a cell sheet, endothelial cells are able to form three-dimensional prevascularized networks and microvascular cavities in the cell sheet, which facilitate the formation of functional vascular networks in the transplanted tissue. ConclusionCell sheet engineering technology is a promising strategy to engineer vascularized tissue, which is still being studied to explore more potential.
ObjectiveTo explore a new method of developing a pre-vascularized cell sheets. MethodsBone marrow mesenchymal stem cells (BMSCs) from 3-week-old Japanese white rabbits were harvested and cultured. Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were added into the culture medium to differentiate into endothelial like cells (ECs) from BMSCs (experimental group), and non-induced cells served as the control group. The cell morphology was observed; and the von Willebrand factor (vWF) and CD31 immunofluorescent staining was used to identify the induced BMSCs. The 2nd generation BMSCs were seeded on a cell culture dish at a cell density of 9×104cells/cm2 and cultured for 14 days to form a thick cell sheet, and ECs from BMSCs were then seeded on the BMSCs sheet at a cell density of 5×104 cells/cm2 to develop pre-vascularized cell sheets and cultured for 3, 7, and 14 days (group A); non-induced BMSCs sheet and only ECs from BMSCs were used as group B and group C, respectively. The CD31 immunofluorescent staining and histological analysis were performed to evaluate the pre-vascularized cell sheet. ResultsBMSCs changed from long fusiform to cobblestone-like morphology after induced by VEGF and bFGF. The expressions of CD31 and vWF were positive in experimental group, but were negative in control group, which suggested that BMSCs have the ability to differentiate into ECs under this condition. After the ECs were seeded on the BMSCs sheet, the ECs migrated and rearranged; intracellular vacuoles and networks were observed. Furthermore, immunofluorescent staining for CD31 also revealed a developing process of tube formation after the ECs were seeded on the BMSCs sheet. The histological evaluations indicated the microvessel lumen formed. However, no similar change was observed in groups B and C. ConclusionBMSCs have the ability to differentiate into ECs after induced by VEGF and bFGF. ECs from BMSCs can develop into vascular network constructs when seeded on the BMSCs sheet, which provides a new method for engineering pre-vascularized tissue construction.