Gene expression study of monocytes/macrophages during early foreign body reaction and identification of potential precursors of myofibroblasts.

Foreign body reaction (FBR), initiated by adherence of macrophages to biomaterials, is associated with several complications. Searching for mechanisms potentially useful to overcome these complications, we have established the signaling role of monocytes/macrophages in the development of FBR and the presence of CD34(+) cells that potentially differentiate into myofibroblasts. Therefore, CD68(+) cells were in vitro activated with fibrinogen and also purified from the FBR after 3 days of implantation in rats.

The remodeling of cardiovascular bioprostheses under influence of stem cell homing signal pathways.

Optimizing current heart valve replacement strategies by creating living prostheses is a necessity to alleviate complications with current bioprosthetic devices such as calcification and degeneration. Regenerative medicine, mostly in vitro tissue engineering, is the forerunner of this optimization search, yet here we show the functionality of an in vivo alternative making use of 2 homing axes for stem cells. In rats we studied the signaling pathways of stem cells on implanted bioprosthetic tissue (photooxidized bovine pericardium (POP)), by gene and protein expression analysis.

The recruitment of primitive Lin(-) Sca-1(+), CD34(+), c-kit(+) and CD271(+) cells during the early intraperitoneal foreign body reaction.

Implanted materials, such as medical devices, provoke the body to initiate an inflammatory reaction, known as the foreign body reaction (FBR), which causes several complications for example in hip prostheses, silicone implants, peritoneal dialysis catheters and left ventricular assist devices. FBR is initiated by macrophage adherence and results in granulation tissue formation. The early immunobiology and development of this tissue is not completely understood, but there are indications from related myofibroblast-forming diseases such as vascular repair and fibrosis that primitive stem cells also play a role in the formation of FBR-tissue.

In vivo cellularization of a cross-linked matrix by intraperitoneal implantation: a new tool in heart valve tissue engineering.

Aim: To use in vivo instead of in vitro cell seeding in heart valve tissue engineering.

Methods And Results: Intraperitoneally preseeded, photo-oxidized bovine pericardial pulmonary valve constructs (group 1) were compared with non-preseeded constructs (group 2) implanted in sheep. All valves functioned normally and were macroscopically intact at explantation [1 week (n = 6) and 1 month (n = 6) in each group], except for one thrombosed leaflet in a group-2 valve at 1 month.