Endothelialization of Titanium Surfaces

Abstract

In the extracellular matrix (ECM), chemical cues are present that control all aspects of cell biology. [1–3] These surfacebound and soluble factors provide the necessary adhesion and signaling for normal cellular activity, and without such matrix support, the cells will quickly apoptose. Implanted device surfaces lack the molecular features that provide guidance to the surrounding cells to afford optimal in vivo integration and function. One class of implanted materials are metal implants, which are commonly used in cardiovascular therapy (e.g., stents) and orthopedic procedures (e.g., hip replacement). While such materials are favored for their inertness and mechanical strength, negative consequences can arise from suboptimal tissue integration. For example, during a coronary angioplasty an occluded coronary artery is opened using a balloon catheter and then a metal stent is inserted to provide a permanent framework supporting vascular patency. If the artery re-occludes due to smooth muscle cell proliferation, in a process called restenosis, a second procedure is required to reestablish blood flow. Restenosis used to occur in about 25% of patients, but with the introduction of stents that elute a mitotic inhibitor, such as paclitaxel, this number has been reduced significantly. [4] However, there is new concern regarding the use of drug-eluting stents owing to an increased thrombolytic potential of two to three fold compared to bare metal stents. [5] An alternative approach to the use of drugs