Integrating the old and new: smart thermoresponsive surfaces and 3D fabrication technologies for tissue engineering

One promising direction of regenerative medicine is the development of cell sheet-based tissue-like constructs. The cell sheets preserve ECM and cell−cell junctions. This may greatly support cell adherence to damaged organ after transplantation. Furthermore, the cell sheets might be used as a building block to engineer large biological tissues with complex organizational architecture. This could be achieved by integrating cell sheets with three-dimensional biomaterial scaffolds. In this study, poly (N-isopropylacrylamide) films were used to produce cell sheets. The pNIPAm films were fabricated by a spin-coating technique. The spin-coating technique allows rapid fabrication of pNIPAm substrates with high reproducibility and uniformity. Because the method of polymer deposition can significantly impact the biological properties of pNIPAm films, the dynamics of cell behavior on spin-coated pNIPAm films of different thicknesses were first examined. Next, biological properties of harvested stromal and epithelial cell sheets after manipulation such as detachment from pNIPAm films, transfer, and re-attachment were assessed. The cell morphology, the pattern and speed of cell sheet recovery and total cell number in cell sheets were analyzed. In addition, the metabolic activity and cell viability of cell sheets before and after detachment and re-attachment were also examined. Next, an integrated-design approach was used to create three-dimensional constructs from cell sheets and three-dimensional natural (acellular pericardial matrix) or three-dimensional synthetic (two-photon polymerization-generated or surface selective laser sintered) scaffolds. These findings should promote further development of implantable tissues engineered from tissue-specific cell sheets and three-dimensional scaffolds.2019-01-1

Natural and synthetic materials for self-renewal, long-term maintenance, and differentiation of induced pluripotent stem cells

Induced pluripotent stem cells (iPSCs) have attracted considerable attention from the public, clinicians, and scientists since their discovery in 2006, and raised huge expectations for regenerative medicine. One of the distinctive features of iPSCs is their propensity to differentiate into the cells of three germ lines in vitro and in vivo. The human iPSCs can be used to study the mechanisms underlying a disease and to monitor the disease progression, for testing drugs in vitro, and for cell therapy, avoiding many ethical and immunologic concerns. This technology offers the potential to take an individual approach to each patient and allows a more accurate diagnosis and specifi c treatment. However, there are several obstacles that impede the use of iPSCs. The derivation of fully reprogrammed iPSCs is expensive, time-consuming, and demands meticulous attention to many details. The use of biomaterials could increase the effi cacy and safety while decreasing the cost of tissue engineering. The choice of a substrate utilized for iPSC culture is also important because cell-substrate contacts infl uence cellular behavior such as selfrenewal, expansion, and differentiation. This Progress Report aims to summarize the advantages and drawbacks of natural and synthetic biomaterials, and to evaluate their role for maintenance and differentiation of iPSCs

Natural and synthetic materials for self-renewal, long-term maintenance, and differentiation of induced pluripotent stem cells

Induced pluripotent stem cells (iPSCs) have attracted considerable attention from the public, clinicians, and scientists since their discovery in 2006, and raised huge expectations for regenerative medicine. One of the distinctive features of iPSCs is their propensity to differentiate into the cells of three germ lines in vitro and in vivo. The human iPSCs can be used to study the mechanisms underlying a disease and to monitor the disease progression, for testing drugs in vitro, and for cell therapy, avoiding many ethical and immunologic concerns. This technology offers the potential to take an individual approach to each patient and allows a more accurate diagnosis and specifi c treatment. However, there are several obstacles that impede the use of iPSCs. The derivation of fully reprogrammed iPSCs is expensive, time-consuming, and demands meticulous attention to many details. The use of biomaterials could increase the effi cacy and safety while decreasing the cost of tissue engineering. The choice of a substrate utilized for iPSC culture is also important because cell-substrate contacts infl uence cellular behavior such as selfrenewal, expansion, and differentiation. This Progress Report aims to summarize the advantages and drawbacks of natural and synthetic biomaterials, and to evaluate their role for maintenance and differentiation of iPSCs