Bioengineered cell-instructive 3D matrices as vehicles for cellular therapies.

The delivery of cells, namely of stem cells, from biomaterial-based vehicles has been used to promote and accelerate functional tissue regeneration. Carrier materials can transport and localize cells into target sites, increase their survival and engraftment, and provide a supportive matrix to assist cellular assembly into a newly formed tissue. Hydrogels are amongst the most widely used carrier materials, as they can entrap and protect cells within a real three-dimensional (3D) microenvironment, and intrinsically present many structural properties of the natural extracellular matrix (ECM). To recreate important features of the native ECM, hydrogels may be bio-functionalized with specific cell-instructive moieties for improved biomimetic properties. The biophysical properties of hydrogels can also be tuned, increasing their versatility, as it is currently recognized that stem cells respond to their biomechanical environment. Here, an overview of some strategies commonly employed in the preparation of biomimetic matrices is presented, using alginate as a model hydrogel.