The size of magnetic nanoparticles is very important. The behavior of the magnetic particle in a magnetic field gradient is dependent upon the particle’s diameter. The ability of the particle to overcome drag force and move in the direction of a magnetic field gradient is dependent on the size of the particle.
Extracellular vesicles are structures released by cells and include exosomes,microvesicles, and apoptotic bodies. These vesicles are an important diagnostic toll since they carry substances from their cells of origin into circulation. The biomolecules contained within, such as RNA and proteins, can be used to determine if the cells that produced them are being affected by a disease. For example, cardiovascular diseases and cancer, lead to increase in specific extracellular vesicles. Isolating these vesicles form body fluids is not a simple task.
The study of biological processes is getting more complex and has to take more factors into account. Physical forces are an important part of normal physiological processes and their impact has been largely overlooked in the in vitro study of biological mechanisms. The cellular force sensing mechanisms play important roles in disease. For example, in atherosclerosis endothelial cells have to respond to pulsatile forces and stiffening of the arteries.
Repair of blood vessels is essential to maintain homeostasis and this process is driven endothelial colony-forming cells. These are vascular lineage-specific progenitor cells that have the ability of driving post-natal vasculogenesis. Endothelial progenitor cells are mobilized into circulation by mediators released due to vascular trauma. Initially, it was though that these cells only acted during embryonic development, but now we know that they are equally important to restore the tissues’ vascularization after disease, especially in heart disease and cancer. Therefore, these cells have therapeutical potential in the treatment of conditions affecting the vascular network. The problem is that these are very rare cells in circulation accounting for only 0.01% of all cells.
Connective tissue progenitors (CTPs) are used as a therapy for bone repair. These cells can be isolated thanks to their expression of hyaluronan, a membrane glycosaminoglycan. Since these cells are rare relatively to other cells in the bone marrow (1 for 20000) it is difficult to obtain enough cells for therapeutical application. The problem with the application in humans is that CTPs need to be isolated from bone marrow suspensions to obtain a high number of viable cells. This procedure implies collecting bone marrow, separating the CTPs and engrafting them in the patient which, due to the complicated nature of rare cell isolations, would need two surgical procedures. Therefore the process of separation needs to be quick and efficient without impairing cell function.
Isolating and culturing primary human hepatocytes is an essential tool to measure liver function, study metabolism and perform hepatotoxicity drug tests. When investigating liver diseases comparative studies of diferent cells within the same patient sample are essential. This approach has many drawbacks since the liver is composed of 80% parenchymal cells (hepatocytes) and 20% non-parenchymal cells, making it difficult to obtain cellular fractions representative of all the subsets present in this organ. Additionally, the obtained cellular fractions usually lack the purity and viability necessary to analyse cell-specific features.
Removal of a protein from solution requires specific recognition of the protein. This has been accomplished through the use of antibodies, epitopes, and functional moieties for years. Now there is a new tool available. It is called a molecularly imprinted polymer (MIP). MIPs have cavities in the polymer matrix that are the perfect fit for the target protein. They have all the right functional groups in all the right places, and this is due to the way they are made.
At the end of the year 1959, Richard Feynman presented his talk entitled There's Plenty of Room at the Bottom to the brightest physicists of the time. The conference participants shared a general feeling that the greatest advances in science had already been made. In a sense, they felt that the good discoveries had already been taken and only scraps remained for them. Feynman challenged this attitude by suggesting that there were more discoveries waiting to be made than they could even imagine. To find them, they needed to look at the nanoscale.
The isolation of circulating tumor cells is essential to diagnostics and metastasis studies. Since these cells are rare compared to the whole cell content of blood, the isolation process poses a challenge. There are several widespread methods of analysis and isolation of circulating tumour cells, from direct analysis of blood by marking tumor cells selectively, to blood processing through flow cytometry and magnetophoresis, that are based on EpCAM expression by tumor cells. However, circulating tumor cells from cancers of non-epithelial origin and cells that go through epithelial to mesenchymal transition do not have EpCAM. Therefore, these approaches have the tendency to lose rare cells.
