Blood vessels , mesenchymal

PDGF Isoforms consist of homo- and heterodimers of A- and B-polypeptide chains and homodimers of C- and D-polypeptide chains PDGFR Consists of PDGFR a and (3 receptors Embryonic development, particularly in the formation of the kidney, blood vessels, and various mesenchymal tissues. Proliferation of connective tissues, glial and smooth muscle cells... 

Fig. 1. Microenvironmental factors and the invasive process. The primary tumor is a heterogeneous mix of cell populations, further diversified by gradients of blood-borne nutrients, oxygen, and drugs. Hypoxia contributes to treatment resistance, upregulates pro-angiogenic and pro-invasive molecules, and helps to maintain cancer stem-like cell populations. Tumor cells may undergo epithelial-to-mesenchymal transition (EMT), enter blood vessels, and disseminate to distant sites where they extravasate, invade, and colonize the tissues. Once established, the cells may undergo the reverse program (mesen-chymal-to-epithelial transition, MET) and proliferate to form metastases, the major reason for treatment failure.

Prior to the 3rd week, embryonic nutrition occurs by diffusion of maternal blood. At that point, development of the primitive blood and blood vessels begins in the extraembryonic mesoderm of the yolk sac. These cells differentiate into angioblasts that form cords and clusters, which in turn canalize. Cells in the peripheiy become flat and form the endothelium, whereas the inner cells give rise to the primitive blood cells. By fusion and continuous budding, the extraembryonic vessels that have contact with maternal circulation establish contact with vessels arising from the embryo proper. The mesenchymal cells surrounding the primitive endothelial cells differentiate to form the muscular and connective tissues of the vessel wall. The primitive heart... 

Studies on the origin and development of the cellular elements of the blood and the so-called endothelial cells which line the blood vessels in the normal embryo are peculiarly difficult on account of the important r61e that wandering mesenchyme cells play in these processes. The problem is also further confused by the perplexing mixture of cells of different origin brought about by the early established circulation of the body fluids. The development of no other embryonic tissue is so disturbed by mechanical and physical conditions. 

Angiolipoma This benign mesenchymal tumour consists of fatty cells and numerous blood vessels, which have a tendency to thrombose. In general, angiolipomas occur singly in both liver lobes. 

Epithelial cells are those that line tissues and organs mesenchymal refers to connective tissues, blood vessels, and lymphatics. 

Classic AMLs are the most common mesenchymal tumors of the kidney. They are composed of variable proportions of adipose cells and spindle and epithelioid smooth muscle cells admixed with and at times appearing to emanate from abnormal thick-walled blood vessels (Eig. 16.39). In patients with TSC, multiple bilateral renal AMLs are found during the third and fourth decades of life. Sporadic AMLs are larger single lesions occurring in older patients. 

Mesenchymal hamartomas are considered to be a developmental anomaly more than true neoplasm. A total of 75% of cases are located in the right lobe of the liver. Histologically MHR arise from the mesenchyma of the portal tract and will have connective tissue, blood vessels, lymphatic spaces, bile ducts and normal hepatocytes (Konez et al. 2001 Cetin et al. 2002). 

Besides that, compressive force can be manipulated to facilitate cell lysis and collect their cellular components for later cell-based assay. Similarly, Wang et al. fabricated a micromechanical stimulator fliat is capable of providing controlled compressive or tensile strain to the cultured cells in vitro (Fig. 4). Experimental characterization of its PDMS membrane deformation showed that the microdevice can provide —6 % compressive to 25 % tensile radial strain to the cultured cells within the membrane center [6], which allowed simultaneous investigation of both mechanical strains on the same cells. Zhou et al. developed a microchip platform with microchannels that resembles the mechanical environment of small blood vessels in vivo (Fig. 5). They demonstrated that the deformation of the membrane by hydraulic pressure induced cyclic circumferential strains on the adhered mesenchymal stem cells and thus caused significant stmctural and biochemical changes to the cells [7]. 

Laschke MW, Schank TE, Scheuer C, Kleer S, Schuler S, Metzger W, et al. Three-dimensional spheroids of adipose-derived mesenchymal stem cells are potent initiators of blood vessel formation in porous polyurethane scaffolds. Acta Biomater June 2013 9(6) 6876-84. 

Wang F, Li Z, Guan J. Fabrication of mesenchymal stem cells-integrated vascular con-stracts mimicking multiple properties of the native blood vessels. J Biomater Sci Polym Ed 2013 24 769 3. 

---