組織科学工学ジャーナル

In -situ selective capture of the Endothelial Progenitor Cell (EPC) in the arterial blood stream can provide antithrombogenic and -cell proliferation potential to implanted intravascular stents. Therefore, we defined molecular mechanisms of EPC activation associated with stent surface-bound proteins. We sought suitable bound protein to capture and proliferate EPCs. Then, to determine whether and how long the surface-bound protein activates intracellular signal-transduction pathways of endothelial cells through its receptor, we studied the phosphorylation of key intracellular macromolecules including Vascular Endothelial Growth Factor (VEGF) Receptor (R)-2 (VEGFR-2), focal adhesion protein-tyrosine kinase, Akt, and extracellular signal-regulated kinase in human umbilical vein endothelial cells. We found the most suitable surface-bound protein was VEGF. Phosphorylation of these macromolecules continued for a long time up to 72 hours. Under these conditions, quantitative RT-PCR revealed time-dependent up-regulation of the mRNAs encoding three major extracellular matrix macromolecules, collagen IV, laminin-5, and fibronectin. Immuno histo- chemical analysis revealed that these macromolecules were secreted on the basal sides of adherent cells over time and that within a few days after initial adhesion occurred, deposition of these macromolecules shut down the EC adhesion. These results demonstrate that activation of the VEGF-VEGFR intracellular signaling pathway is significant for in situ EPC capture technology for intravascular stents, although further in vivo studies should be done to confirm these processes.

Background: Bypass surgery for atherosclerosis is confronted with the absence of endothelial cells in the lumen of vascular prosthesis in humans. This imposes a risk of thrombosis. New biomaterials try to minimize surface thrombogenicity.

Methods: Knitted polyethylene terephthalate (PET) vascular graft patches were impregnated with degradable polyester polymers: poly (L-lactide-co-glycolide) (PLG) or poly (L-lactide-co-glycolide-co-ε-caprolactone) (PLGC). The luminal surface was coated with collagen type I (Co) to which extracellular matrix proteins laminin (LM), fibronectin (FN), or surface fibrin gel (Fb) were attached. Three types of prostheses (PET, PET–PLG and PET– PLGC) and 5 types of protein assemblies (+Co, +Co/LM, +Co/FN, +Co/Fb, +Co/Fb/FN) were fabricated. Scanning electron microscopy and measurements of the water contact angles were performed. The development of a bovine endothelial cell layer was studied in a static culture for 1 week.

Results: The cells reached confluence on all PET surfaces with the highest final density on +Co/FN. Impregnation of PET with polymers made it less adhesive for cells in the following order: PET > PET–PLG > PET– PLGC. However, additional coating with the protein assemblies enhanced the endothelial cell growth, especially on fibrin-containing surfaces.

Conclusion: Tri-component vascular grafts composed of PET, copolymers and cell-adhesive assemblies were fabricated. The endothelial lining on the polymer-coated grafts was promoted after modification with the protein multilayers.
Artificial vascular prostheses have been made of non-degradable, non-compliant and thrombogenic materials for more than 50 years. Thus, they resemble passive tubing. Potential bio-activation by degradable materials and by introduction of living endothelial cells may approximate these materials to native artery. This work provided a method to include bio-degradable polymers into vascular graft and to facilitate the growth of cell lining via adhesive protein multilayers.

Serosal membranes cover body cavities and guarantee frictionless gliding of inner organs. Serosal damage carries the risk of adhesion formation, which represents a relevant postoperative complication. Due to pathophysiological similarities between serous and dermal wound healing, the efficacy of SupraSeal® in intraabdominal adhesion prevention was investigated at early time points. After standardized serosal damage, Wistar rats were examined macroscopically, histologically and immunohistochemically on days two, four and eight postoperatively. On day eight, all specimens of the control group presented distinctive adhesions consisting of fibrous tissue bands. In contrast, most specimens covered by SupraSeal® were adhesion-free. Merely mild adhesion formation due to suture material used for fixation was detected. Histologically, SupraSeal® revealed rapid clearance of fibrin and a marked lack of fibrosis. For the first time, the histomorphological effects of SupraSeal® on adhesion formation over time are described and the relevance of the early stage of wound healing elucidated.

In current year tissue damage, repair and regeneration has become a very serious clinical problem which
accounts for billions of health issues all over the world every year. Many tissue repair substitute and techniques
are now available although it is having many drawback; these disadvantages give a good reason for the continued
research for more acceptable tissue engineered substitutes. Research that are presently going on to improve the
design strategies to overcome the surgical outcomeinvolves the development of biopolymers and synthetic polymers
as primary scaffold or luminal fillers as secondary scaffold with the tailored mechanical, physical and chemical
properties. Biodegradable scaffolds for regenerated tissue is preferred since no foreign body will be left in the host
hence there is no need of second surgery so it involves less complications. The purpose of the review article is to
discuss about the various tissue engineering researches taking place around the globe, recent developments, and
different biomaterials used for it and applications of tissue engineering. The improvement and validation ofmodalities
which are capable of spontaneous regeneration would be valuable to properly grade injuries and rapidly identify
cases which require surgical intervention with less ambiguity. This review article focuses on different biomaterials
used for tissue regeneration or tissue restoration and their methods of fabricationas well as their application in bone,
nerve, cartilage, skin tissue engineering.

The regenerative medicine is a fast growing innovation of health care for replacement of damaged or dysfunctional human organs or tissues with functional normal. However, the shortage of graft donors is the major concern of this treatment. To solve this problem, pluripotent or multipotent stem cells, which have the potential to differentiate into multiple lineages, provide an unlimited source of desired cells for transplantation. Even though stem cell therapy became a promising tool for regenerative medicine, unfortunately some unexpected adverse effects occurred in such treatments. Especially the incidence of life-threatening event from malignant teratomas, which are generated from undifferentiated stem cells in graft, is greater than that from damaged organs or tissues per se. Here, in this article the safety issues associated with stem cell therapy are reviewed, and in warnings for patients who want to receive this therapy are also mentioned.