Background: Bone marrow-derived mesenchymal stem cells (BMSCs) are a widely researched adult stem cell population capable of differentiation into various lineages. Because many promising applications of tissue engineering require cell expansion following harvest and involve the treatment of diseases and conditions found in an aging population, the effect of donor age and ex vivo handling must be understood in order to develop clinical techniques and therapeutics based on these cells. Furthermore, there currently exists little understanding as to how these two factors may be influenced by one another. Results: Differences in the adipogenic, chondrogenic, and osteogenic differentiation capacity of murine MSCs harvested from donor animals of different age and number of passages of these cells were observed. Cells from younger donors adhered to tissue culture polystyrene better and proliferated in greater number than those from older animals. Chondrogenic and osteogenic potential decreased with age for each group, and adipogenic differentiation decreased only in cells from the oldest donors. Significant decreases in differentiation potentials due to passage were observed as well for osteogenesis of BMSCs from the youngest donors and chondrogenesis of the cells from the oldest donors. Conclusion: Both increasing age and the number of passages have lineage dependent effects on BMSC differentiation potential. Furthermore, there is an obvious interplay between donor age and cell passage that in the future must be accounted for when developing cell-based therapies for clinical use.

Microtia is a congenital external ear malformation that can seriously influence the psychological and physiological well-being of affected children. The successful regeneration of human ear-shaped cartilage using a tissue engineering approach in a nude mouse represents a promising approach for auricular reconstruction. However, owing to technical issues in cell source, shape control, mechanical strength, biosafety, and long-term stability of the regenerated cartilage, human tissue engineered ear-shaped cartilage is yet to be applied clinically. Using expanded microtia chondrocytes, compound biodegradable scaffold, and in vitro culture technique, we engineered patient-specific ear-shaped cartilage in vitro. Moreover, the cartilage was used for auricle reconstruction of five microtia patients and achieved satisfactory aesthetical outcome with mature cartilage formation during 2.5years follow-up in the first conducted case. Different surgical procedures were also employed to find the optimal approach for handling tissue engineered grafts. In conclusion, the results represent a significant breakthrough in clinical translation of tissue engineered human ear-shaped cartilage given the established in vitro engineering technique and suitable surgical procedure. This study was registered in Chinese Clinical Trial Registry (ChiCTR-ICN-14005469).

Although several studies have shown that dermal fibroblasts possess adipogenic, osteogenic or chondrogenic differentiation potential, no study has characterized this cell population in detail, and there is as yet no evidence that a single dermal fibroblast can differentiate into all these types of cells. In this study, dermal fibroblasts were isolated from human foreskin using a regular dermal fibroblast culture system. These cells could be expended in adherent culture for over 40 cell doublings. In addition, dermal fibroblasts exhibited adipogenic, osteogenic and chondrogenic phenotypes when they were cultured in the presence of certain inducers. Importantly, clonal analysis showed that 6.4% (3/47) of the single-cell-derived clones were tripotent, 19.1% (9/47) of the clones were bipotent, and 10.6% (5/47) of the clones were unipotent. Furthermore, one of the three tested tripotent clones exhibited neurogenic and hepatogenic differentiation potential. Phenotypic analyses showed that the tripotent fibroblasts were nestin^– vimentin⁺, which is different from the dermis-derived stem cells reported by others. These results indicate that dermal fibroblasts are a heterogeneous population containing progenitors with various levels of differentiation potential, and the nestin^– vimentin⁺ fibroblasts may represent a novel type of multipotent adult stem cells in human dermis.

Introduction Components of blood vessel Principle of vessel engineering Seeding cells sources Biodegradable scaffolds Vessel engineering in vitro Clinical applications Future perspectives Vascular grafts are in large demand for coronary and peripheral bypass surgeries. Although synthetic grafts have been developed, replacement of vessels with purely synthetic polymeric conduits often leads to the failure of such graft, especially in the grafts less than 6 mm in diameter or in the areas of low blood flow, mainly due to the early formation of thrombosis. Moreover, the commonly used materials lack growth potential, and long‐term results have revealed several material‐related failures, such as stenosis, thromboembolization, calcium deposition and infection. Tissue engineering has become a promising approach for generating a bio‐compatible vessel graft with growth potential. Since the first success of constructing blood vessels with collagen and cultured vascular cells by Weinberg and Bell, there has been considerable progress in the area of vessel engineering. To date, tissue‐ engineered blood vessels (TEBVs) could be successfully constructed in vitro, and be used to repair the vascular defects in animal models. This review describes the major progress in the field, including the seeding cell sources, the biodegradable scaffolds, the construction technologies, as well as the encouraging achievements in clinical applications. The remaining challenges are also discussed.