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Stem cells are known for their capacity to self-renew and differentiate into at least one specialized cell type. Mesenchymal stem cells (MSCs) were isolated initially from bone marrow but are now known to exist in all vascularized organ or tissue in adults. MSCs are particularly relevant for therapy due to their simplicity of isolation and cultivation. The International Society for Cellular Therapy (ISCT) has proposed a set of standards to define hMSCs for laboratory investigations and preclinical studies: adherence to plastic in standard culture conditions; in vitro differentiation into osteoblasts, adipocytes, and chondroblasts; specific surface antigen expression in which !95% of the cells express the antigens recognized by CD105, CD73, and CD90, with the same cells lacking ( 2% positive) the antigens CD45, CD34, CD14 or CD11b, CD79a or CD19, and HLA-DR. In this review we will take an historical overview of how umbilical cord blood, bone marrow, adipose-derived, placental and amniotic fluid, and menstrual blood stem cells, the major sources of human MSC, can be obtained, identified and how they are being used in clinical trials to cure and treat a very broad range of conditions, including heart, hepatic, and neurodegenerative diseases. An overview of protocols for differentiation into hepatocytes, cardiomyocytes, neuronal, adipose, chondrocytes, and osteoblast cells are highlighted. We also discuss a new source of stem cells, induced pluripotent stem cells (iPS cells) and some pathways, which are common to MSCs in maintaining their pluripotent state.

The increasing interest in stem cell research is linked to the promise of developing treatments for many lifethreatening, debilitating diseases, and for cell replacement therapies. However, performing these therapeutic innovations with safety will only be possible when an accurate knowledge about the molecular signals that promote the desired cell fate is reached. Among these signals are transient changes in intracellular Ca2+ concentration [Ca2+]i. Acting as an intracellular messenger, Ca2+ has a key role in cell signaling pathways in various differentiation stages of stem cells. The aim of this chapter is to present a broad overview of various moments in which Ca2+-mediated signaling is essential for the maintenance of stem cells and for promoting their development and differentiation, also focusing on their therapeutic potential.

Graphene and its derivatives, due to a wide range of unique properties that they possess, can be used as starting material for the synthesis of useful nanocomplexes for innovative therapeutic strategies and biodiagnostics. Here, we summarize the latest progress in graphene and its derivatives and their potential applications for drug delivery, gene delivery, biosensor and tissue engineering. A simple comparison with carbon nanotubes uses in biomedicine is also presented. We also discuss their in vitro and in vivo toxicity and biocompatibility in three different life kingdoms (bacterial, mammalian and plant cells). All aspects of how graphene is internalized after in vivo administration or in vitro cell exposure were brought about, and explain how blood-brain barrier can be overlapped by graphene nanomaterials.

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