Over the years, cardiovascular diseases continue to increase and affect not only human health but also the economic stability worldwide. The advancement in tissue engineering is contributing a lot in dealing with this immediate need of alleviating human health. Blood vessel diseases are considered as major cardiovascular health problems. Although blood vessel transplantation is the most convenient treatment, it has been delimited due to scarcity of donors and the patient’s conditions. However, tissue-engineered blood vessels are promising alternatives as mode of treatment for blood vessel defects. The purpose of this paper is to show the importance of the advancement on biofabrication technology for treatment of soft tissue defects particularly for vascular tissues. This will also provide an overview and update on the current status of tissue reconstruction especially from autologous stem cells, scaffolds, and scaffold-free cellular transplantable constructs. The discussion of this paper will be focused on the historical view of cardiovascular tissue engineering and stem cell biology. The representative studies featured in this paper are limited within the last decade in order to trace the trend and evolution of techniques for blood vessel tissue engineering.

Background: Although the clinical results of autologous chondrocyte implantation for articular cartilage defects have recently improved as a result of advanced techniques based on tissue engineering procedures, problems with cell handling and scaffold imperfections remain to be solved. A new cell-sheet technique has been developed, and is potentially able to overcome these obstacles. Chondrocyte sheets applicable to cartilage regeneration can be prepared with this cell-sheet technique using temperature-responsive culture dishes. However, for clinical application, it is necessary to evaluate the characteristics of the cells in these sheets and to identify their similarities to naive cartilage. Results: The expression of SOX 9, collagen type 2, 27, integrin α10, and fibronectin genes in triple-layered chondrocyte sheets was significantly increased in comparison to those in conventional monolayer culture and in a single chondrocyte sheet, implying a nature similar to ordinary cartilage. In addition, immunohistochemistry demonstrated that collagen type II, fibronectin, and integrin α10 were present in the triple-layered chondrocyte sheets. Conclusion: The results of this study indicate that these chondrocyte sheets with a consistent cartilaginous phenotype and adhesive properties may lead to a new strategy for cartilage regeneration.

We have carried out the fabrications of a barrier layer on a polyethersulfon (PES) film and organic light emitting diode (OLED) based on a plastic substrate by means of atomic layer deposition (ALD). Simultaneous deposition of 30 nm AlO_x film on both sides of the PES film gave a water vapor transition rate (WVTR) of 0.062 g/m²/day (@38°C, 100% R.H.). Further, the double layer of 200 nm SiNx film deposited by plasma enhanced chemical vapor deposition (PECVD) and 20 nm AlOx film by ALD resulted in a WVTR value lower than the detection limit of MOCON. We have investigated the OLED encapsulation performance of the double layer using the OLED structure of ITO / MTDATA (20 nm) / NPD (40 nm) / AlQ (60 nm) / LiF (1 nm) / Al (75 nm) on a plastic substrate. The preliminary life time to reach 91% of the initial luminance (1300 cd/m²) was 260 hours for the OLED encapsulated with 100 nm of PECVD-deposited SiNx and 30 nm of ALD-deposited AlO_x.

The term “immunoisolation” refers to the encapsulation of a graft in a selectively permeable membrane. Encapsulation of cellular grafts may provide a way to protect the graft from immune attack without the need for immunosuppressive agents. Although numerous types of artificial materials have been used for encapsulating membranes, their incomplete biocompatibility causes foreign body reaction against the membranes. A new technique has been developed, called cell sheet engineering using temperature-responsive culture dishes, that allows the use of living cells as an immunoisolating membrane in this study. Using this method, the cultured cells can be easily harvested in the shape of a sheet by a simple change of the temperature without the use of proteolytic enzymes. A cell sheet can be created with three-dimensional structure by making multiple cell sheet layers. In this study, a new technique of macroencapsulation (bioartificial organs) has been developed using chondrocyte sheets. Among the various candidate cells, pancreatic islet cells were selected for a bioartificial organ in this study. A chondrocyte sheeting immunodelusive immunoisolated bioartificial pancreas (CSI-BAP) was manufactured by means of cell sheet engineering. An auricular cartilage, which is a histologically elastic cartilage from dogs (beagle), was used as a source of immunoisolating membrane. CSI-BAP was made by multilayering the chondrocyte sheets, and the donor's islets were located between each sheet. Islets were isolated and prepared from the dog (ALLO-model) and Brown Norway (BN) rat (XENO-model). The CSI-BAP was cultured for 83 days and the cultured medium was collected every 24 h to measure the insulin concentrations. The CSI-BAP was examined histologically using hematoxyhin and eosin (H&E), and azan dye staining. In addition, immunohistochemical staining was performed to demonstrate the insulin production of CSI-BAP. Insulin secretion of CSI-BAP on day 16 was reduced to 21.4% of the insulin secretion level of day 10, which was the start point of measurement. Although a gradual reduction was observed, insulin secretion was maintained for 3 months. The CSI-BAP was capable of secreting insulin to the culture medium during the observation period. Histological evaluations demonstrated the good viability of the islets, and immunohistochemistry showed the positive staining of insulin. This novel technology may be used for other kinds of endocrine cells or hepatocytes, which may become the models for immunoisolated bioartificial organs in the near future.

Background: Fluorescence correlation spectroscopy (FCS) provides information about translational diffusion of fluorescent molecules in tiny detection volumes at the single-molecule level. In normal states, cartilage tissue lacks vascularity, so chondrocyte metabolism depends on diffusion for molecular exchanges. The abundant extracellular matrix (ECM) of cartilage is maintained by a limited number of chondrocytes. ECM plays an important role in the regulation of chondrocyte functions. In this study, FCS was used to measure diffusion behaviors of albumin, the major protein of the intra-articular space, using normal and degenerated cartilage. Preliminary investigation of fluorescence dyes including Alexa 488, Rhodamine 6G and Rhodamine 123 was conducted to evaluate their properties in cartilage. Results: The results indicate that the diffusion behaviors of fluorescently lableded albumin can be observed using FCS in both normal and chemically degenerated cartilage. Conclusions: This work demonstrates the capability of FCS for direct measurement of diffusion in cartilaginous ECM. When the diffusion characteristics of fluorescent probes in ECM are clarified using FCS evaluation, FCS will be applicable as a method for early diagnosis of osteoarthritis, which is accompanied by increased abnormalities of ECM and also as tool for evaluating bio-engineered artificial cartilage for autologous chondrocyte implantation.