Tissue engineering of teeth requires the coordinated formation of correctly shaped crowns, roots, and periodontal ligament. Previous studies have shown that the dental mesenchyme controls crown morphogenesis and epithelial histogenesis during tooth development in vivo, but little is known about the inductive potential of dissociated mesenchymal cells used in ex vivo cultures. A 2-step method is described in which, by using different types of reassociations between epithelial and mesenchymal tissues and/or cells from mouse embryos, reassociations were cultured in vitro before in vivo implantation. In vitro, the reassociated tissues developed and resulted in tooth-like structures that exhibited normal epithelial histogenesis and allowed the functional differentiation of odontoblasts and ameloblasts. After implantation, the reassociations formed roots and periodontal ligament, the latter connected to developing bone. The shape of the crown, initially suspected to depend on the integrity of the mesenchyme, could be modulated by adjusting the number of dissociated mesenchymal cells reassociated with the epithelial compartment. Based on these results, we propose a refined strategy for tooth tissue engineering that may help to eventually generate morphologically defined teeth.

The implantation of cultured dental cell-cell re-associations allows for the reproduction of fully formed teeth, crown morphogenesis, epithelial histogenesis, mineralized dentin and enamel deposition, and root-periodontium development. Since vascularization is critical for organogenesis and tissue engineering, this work aimed to study: (a) blood vessel formation during tooth development, (b) the fate of blood vessels in cultured teeth and re-associations, and (c) vascularization after in vivo implantation. Ex vivo, blood vessels developed in the dental mesenchyme from the cap to bell stages and in the enamel organ, shortly before ameloblast differentiation. In cultured teeth and re-associations, blood-vessel-like structures remained in the peridental mesenchyme, but never developed into dental tissues. After implantation, both teeth and re-associations became revascularized, although later in the case of the re-associations. In implanted re-associations, newly formed blood vessels originated from the host, allowing for their survival, and affording conditions organ growth, mineralization, and enamel secretion.

The temporomandibular joint (TMJ) is an articulation formed between the temporal bone and the mandibular condyle which is commonly affected. These affections are often so painful during fundamental oral activities that patients have lower quality of life. Limitations of therapeutics for severe TMJ diseases have led to increased interest in regenerative strategies combining stem cells, implantable scaffolds and well-targeting bioactive molecules. To succeed in functional and structural regeneration of TMJ is very challenging. Innovative strategies and biomaterials are absolutely crucial because TMJ can be considered as one of the most difficult tissues to regenerate due to its limited healing capacity, its unique histological and structural properties and the necessity for long-term prevention of its ossified or fibrous adhesions. The ideal approach for TMJ regeneration is a unique scaffold functionalized with an osteochondral molecular gradient containing a single stem cell population able to undergo osteogenic and chondrogenic differentiation such as BMSCs, ADSCs or DPSCs. The key for this complex regeneration is the functionalization with active molecules such as IGF-1, TGF-β1 or bFGF. This regeneration can be optimized by nano/micro-assisted functionalization and by spatiotemporal drug delivery systems orchestrating the 3D formation of TMJ tissues.

THE passage of immunocompetent cells across the blood–brain barrier (BBB) is regulated at the level of the cerebral capillaries which have specific morphological and biochemical properties. We have developed and characterized an in vitro model of the BBB using immortalized human endothelial cells (ECV 304) induced by rat astrocytes. In this model, endothelial cells are attached together by continuous intercellular junctions with numerous tight junctions, develop a permeability barrier having a significant transcellular electrical resistance, possess high activities of γ-glutamyl transpeptidase (γ-GTP) and express the brain-type glucose transporter 1 (GLUT-1). These parameters are also characteristic of brain capillary endothelial cells. Under the culture conditions used, the ECV 304 cells express the intercellular adhesion molecule-1 (ICAM-1) on the external plasma membrane at concentrations which could permit lymphocyte adhesion to be studied.