Endothelial Progenitor Cells Promote Directional Three-Dimensional Endothelial Network Formation by Secreting Vascular Endothelial Growth Factor

Endothelial progenitor cell (EPC) transplantation induces the formation of new blood-vessel networks to supply nutrients and oxygen, and is feasible for the treatment of ischemia and cardiovascular diseases. However, the role of EPCs as a source of proangiogenic cytokines and consequent generators of an extracellular growth factor microenvironment in three-dimensional (3D) microvessel formation is not fully understood. We focused on the contribution of EPCs as a source of proangiogenic cytokines on 3D microvessel formation using an in vitro 3D network model. To create a 3D network model, EPCs isolated from rat bone marrow were sandwiched with double layers of collagen gel. Endothelial cells (ECs) were then cultured on top of the upper collagen gel layer. Quantitative analyses of EC network formation revealed that the length, number, and depth of the EC networks were significantly enhanced in a 3D model with ECs and EPCs compared to an EC monoculture. In addition, conditioned medium (CM) from the 3D model with ECs and EPCs promoted network formation compared to CM from an EC monoculture. We also confirmed that EPCs secreted vascular endothelial growth factor (VEGF). However, networks cultured with the CM were shallow and did not penetrate the collagen gel in great depth. Therefore, we conclude that EPCs contribute to 3D network formation at least through indirect incorporation by generating a local VEGF gradient. These results suggest that the location of EPCs is important for controlling directional 3D network formation in the field of tissue engineering

Exhaustion of nucleus pulposus progenitor cells with ageing and degeneration of the intervertebral disc.

Despite the high prevalence of intervertebral disc disease, little is known about changes in intervertebral disc cells and their regenerative potential with ageing and intervertebral disc degeneration. Here we identify populations of progenitor cells that are Tie2 positive (Tie2+) and disialoganglioside 2 positive (GD2+), in the nucleus pulposus from mice and humans. These cells form spheroid colonies that express type II collagen and aggrecan. They are clonally multipotent and differentiated into mesenchymal lineages and induced reorganization of nucleus pulposus tissue when transplanted into non-obese diabetic/severe combined immunodeficient mice. The frequency of Tie2+ cells in tissues from patients decreases markedly with age and degeneration of the intervertebral disc, suggesting exhaustion of their capacity for regeneration. However, progenitor cells (Tie2+GD2+) can be induced from their precursor cells (Tie2+GD2-) under simple culture conditions. Moreover, angiopoietin-1, a ligand of Tie2, is crucial for the survival of nucleus pulposus cells. Our results offer insights for regenerative therapy and a new diagnostic standard

Inflammatory bowel disease in Tokushima prefecture : A report of questionnaire investigation

To investigate the number of cases and clinical features of inflammatory bowel disease, a questionnaire was sent to 1,271 hospitals or clinics in Tokushima prefecture. A total of 320 cases were collected from 60 institutes for the period from January to December 1997. Eight cases were excluded from this study because of duplicated report (6 cases) and inadequate diagnosis (2 cases). Finally, 312 cases were investigated on their clinical features, treatments, complications, and prognosis. The cases included 195 ulcerative colitis (male 106, female 83, gender unknown 6 cases, age ranged 9-81, mean 39.5± 14.3 (standard deviation (SD) years old), 69 Crohn's disease (male 39, female 24, gender unknown 6 cases, age ranged 17-87, mean 35.1±10.5 (SD) years old), 28 ischemic colitis (male 11, female 17, mean age 65.9±12.6 (SD) years old), 9 intestinal tuberculosis (male 1, female 6, gender unknown 2, age 66.9±6.1 (SD) years old), 4 intestinal Behcet (male 3, female 1, age 39.0±14.2 (SD) years old), 6 simple ulcers (male 3, female 3, age 67.7±11.8 (SD) years old), and a case of aphtous enteritis. Two toxic megacolon cases and 5 colorectal cancer cases were reported among the 195 ulcerative colitis patients. 44 cases out of 69 Crohn's disease patients were received surgical treatment because of severe complications including perforation (12 cases), stenosis (10 cases), internal fistula formation (8 cases) and so on. However, no case died because of the diseases except 3 untraceable patients

Development of an in vivo tissue-engineered, autologous heart valve (the biovalve) : preparation of a prototype model

Objective: This study aimed to develop an autologous heart valve without using traditional in vitro tissue-engineering methods, which necessitate complicated cell management protocols under exceptionally clean laboratory facilities. Methods: An autologous heart valve construct composed of trileaflets was prepared using a specially designed mold. The mold was prepared by covering a silicone rod with a crown-shaped tubular polyurethane scaffold containing 3 horns. The mold was implanted in the dorsal subcutaneous space in Japan White rabbits for 4 weeks. After harvesting, the implanted trileaflet valve-shaped structure with an internal diameter of either 5 or 20 mm was obtained by trimming the membranous tissue formed between the horns located around the silicone rod. The valve substitute was examined both macroscopically and histologically. The tensile strength of the leaflets was measured to rupture. The degree of regurgitation in valve function was evaluated using a flow circuit by calculating the ratio of the regurgitation volume to the forward flow volume. Results: After implantation, the mold was completely covered with connective tissue consisting mostly of collagen and fibroblasts. Harvesting of the mold was straightforward, because there was little adhesion between the formed tissue and the native skin tissue. The trileaflet heart valve construct was obtained after withdrawing the inserted rods and trimming the membranous tissues formed between the horns of the scaffold. It was firmly attached to the scaffold, the interstices and surface of which revealed connective tissues composed of components similar to those of the leaflet tissue. Although the mechanical properties of the leaflet tissue were less efficient than those of the native porcine aortic valve leaflets, satisfactory valvular functions were demonstrated under pulsatile conditions using a flow circuit. No regurgitation was observed under retrograde hydrostatic pressures of up to 60 mm Hg, the physiologic pressure acting on the aortic valves during retrograde aortic flow. Conclusions: The biovalve, an autologous, in vivo tissue-engineered, trileaflet, valve-shaped construct, was developed using our novel in-body tissue architecture technology. The biovalve has the potential to be an ideal prosthetic heart valve, with excellent biocompatibility to the growth of the recipient’s heart

Study on the Sliding Friction of Endothelial Cells Cultured on Hydrogel and the Role of Glycocalyx on Friction Reduction

In this study, we investigated the sliding friction of human umbilical vein endothelial cell (HUVEC) monolayer cultured on poly(sodium p-styrene sulfonate) (PNaSS) gel, intending to elucidate the role of the glycocalyx on the surface of endothelial cell (EC) in friction reduction. Three sets of HUVEC monolayers were investigated: 1) as-cultured HUVEC monolayer, 2) HUVEC monolayer treated by transforming growth factor υ1 (TGF-υ1), which increased glycocalyx by 148%, 3) HUVEC monolayer treated by heparinase I, which reduced glycocalyx by 57%, both were compared with that of the as prepared one. When being slid on flat glass surface, the frictional stress of HUVEC monolayer decreased in the order of heparinase I-treated > as-cultured > TGF-υ1-treated samples. The results suggested that glycocalyx may play a role in reducing the friction of endothelial cell monolayer