The extracellular matrix critically controls cancer cell behavior by inducing several signaling pathways through cell membrane receptors. Besides conferring structural properties to tissues around the tumor, the extracellular matrix is able to regulate cell proliferation, survival, migration and invasion. Among these receptors, the integrins family constitutes a major class of receptors that mediate cell interactions with extracellular matrix components. Twenty years ago, a new class of extracellular matrix receptors has been discovered. These tyrosine kinase receptors are the two discoidin domain receptors DDR1 and DDR2. DDR1 was first identified in the Dictyostelium discoideum and was shown to mediate cell aggregation. DDR2 shares highly conserved sequences with DDR1. Both receptors are activated upon binding to collagen, one of the most abundant proteins in extracellular matrix. While DDR2 can only be activated by fibrillar collagen, particularly types I and III, DDR1 is mostly activated by type I and IV collagens. In contrast with classical growth factor tyrosine kinase receptors which display a rapid and transient activation, DDR1 and DDR2 are unique in that they exhibit delayed and sustained receptor phosphorylation upon binding to collagen. Recent studies have reported differential expression and mutations of DDR1 and DDR2 in several cancer types and indicate clearly that these receptors have to be taken into account as new players in the different aspects of tumor progression, from non-malignant to highly malignant and invasive stages. This review will discuss the current knowledge on the role DDR1 and DDR2 in malignant transformation, cell proliferation, epithelial to mesenchymal transition, migratory and invasive processes, and finally the modulation of the response to chemotherapy. These new insights suggest that DDR1 and DDR2 are new potential targets in cancer therapy.

Hydrogels are important biomaterials that have several applications in drug and cell delivery, tissue engineering, three-dimensional (3D) printing and more recently, in sensing and actuating applications. With the advent of self-healing hydrogels, it is becoming possible to have smarter materials with sustainable mechanical properties under stress and also added functionalities. The mechanisms responsible for the self-healing behavior of these materials are related to their internal structure and processes triggered by damage they may sustain. These mechanisms rely on either chemical bonding or physical interactions of the structural components of hydrogels, or on both. Many self-healing hydrogels have been developed and tested in vitro and in animals. However, there are still challenges, especially with healing characteristics that need to be addressed and investigated in animal experiments before their clinical applications can be initiated, for which a multidisciplinary approach is required. In the current paper, various biomedical applications of self-healing hydrogels are discussed in detail, highlighting current challenges and future prospects.

The rising and diversity of many human vascular diseases pose urgent needs for the development of novel therapeutics. Stem cell therapy represents a challenge in the medicine of the twenty-first century, an area where tissue engineering and regenerative medicine gather to provide promising treatments for a wide variety of diseases. Indeed, with their extensive regeneration potential and functional multilineage differentiation capacity, stem cells are now highlighted as promising cell sources for regenerative medicine. Their multilineage differentiation involves environmental factors such as biochemical, extracellular matrix coating, oxygen tension, and mechanical forces. In this review, we will focus on human stem cell sources and their applications in vascular regeneration. We will also discuss the different strategies used for their differentiation into both mature and functional smooth muscle and endothelial cells.