Multivesicular droplets: a cell model system to study compartmentalised biochemical reactions.

Multivesicular vesicles (MVVs) are artificial liposomal structures widely used as a platform to study the compartmentalisation of cells and as a scaffold for artificial cell/protocell models. Current preparation techniques for MVVs, however, offer poor control on the size, lamellarity, and loading of inner lipid vesicles. Here, we introduce a microfluidic device for the production of multivesicular droplets (MVDs): a novel model system combining the ease of use and control of droplet microfluidics with the biological relevance of MVVs. We use a perfluorinated carrier phase with a biocompatible surfactant to generate monodisperse droplets of an aqueous giant unilamellar lipid vesicle suspension. The successful on-chip formation and stability of MVDs is verified through high-speed microscopy. For bright field or fluorescence microscopy inspection, the MVDs are trapped in an array where the integrity of both lipid vesicles and droplets is preserved for up to 15 minutes. Finally, we show a two-step enzymatic reaction that takes place across the lipid vesicle membranes; the second reaction step occurs in the vesicle's interior, where the enzyme is encapsulated, while both the substrate and fluorescent product permeate across the membrane. Our approach opens the possibility to mimic artificial organelles with optimised reaction parameters (pH, ions, etc.) in each compartment.

Multipotent Differentiation of Human Dental Pulp Stem Cells: a Literature Review.

The advent of regenerative medicine has brought us the opportunity to regenerate, modify and restore human organs function. Stem cells, a key resource in regenerative medicine, are defined as clonogenic, self-renewing, progenitor cells that can generate into one or more specialized cell types. Stem cells have been classified into three main groups: embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and adult/postnatal stem cells (ASCs). The present review focused the attention on ASCs, which have been identified in many perioral tissues such as dental pulp, periodontal ligament, follicle, gingival, alveolar bone and papilla. Human dental pulp stem cells (hDPSCs) are ectodermal-derived stem cells, originating from migrating neural crest cells and possess mesenchymal stem cell properties. During last decade, hDPSCs have received extensive attention in the field of tissue engineering and regenerative medicine due to their accessibility and ability to differentiate in several cell phenotypes. In this review, we have carefully described the potential of hDPSCs to differentiate into odontoblasts, osteocytes/osteoblasts, adipocytes, chondrocytes and neural cells.