Interaction implants-living tissues

Figure 9.18 An artist s attempt to capture some of the complexity involved in the interaction between a material and living tissue, exemplified here by a titanium implant in bone. Note the wide range of dimensions and time scales that are relevant. (Kasemo and Lausmaa, 1994.)...

The Interaction of Implant Materials and Living Tissues A Basic Approach... 

Inflammation is generally defined as the reaction of vascularized living tissue to local injury, that is, implantation of a biomaterial, prosthesis, medical device, or tissue-engineered device. Immediately following injury, blood-material interactions occur and a provisional matrix is formed that consists... 

Since the growth of connective tissue is a well known response of the body to inflammation process provoked by foreign bodies (e.g., PP and Moplen implants), the absence of germination of Moplen samples by connective tissue can be explained by the more inert character of this material than of polypropylene. Since Moplen properties remain unchanged even after 4 years of implantation, the slow interaction of this polymer with living tissue can be assumed. To test this assumption, a more detailed analysis of the effect of connective tissue and tissue liquid on polymer was made. 

In the musculoskeletal system, bone is the primary tissue/organ interacting with prosthetic implants/biomaterials and their interface is a crucial region where the interactions pertinent to new tissue formation and implant efficacy occur. Bone is a complex biological system that comprises both hierarchical structures and living boneremodeling components. The architecture of bone is composed of nanoscale fibrous... 

Is it possible to construct an adequate data base of materials properties of both manufactured materials and biological tissues and fluids such that in vitro simulations can be used to validate future implant designs before in vivo service While there are no apparent intellectual barriers to attaining such a goal, it clearly lies in the distant future, given the complexity of possible interactions between manufactured materials and living systems. 

The main problems experienced when electrodes are in contact with, or implanted into, living cells (or tissues) are traumatization of the cells and the interaction of the biological medium with electrodes, both of which frequently impose significant uncertainties on the experimental data obtained, and should be kept to a minimum. The latter problem becomes less serious when the size of the electrode is made much smaller than the size of the cells or tissues, though some effects caused by the electrode may still remain. The recent development in microvoltammet-ric techniques, including fabrication of electrodes of / m dimensions [3, 4] and electronic devices to facilitate the measurement of very small currents, offers dramatic improvements in the quality of the data obtained in vivo. Furthermore, some experiments which were impossible to perform previously have recently become possible with the aid of these techniques. 

Adsorption of proteins from solution onto synthetic materials is a key factor in the response of a living body to artificial implanted materials and devices. Adsorbed proteins mediate cell attachment and spreading through specific peptide sequence-integrin receptor interactions and may therefore favorably influence the mechanical stability of the subsequently developed tissue—implant interface. However, the uncontrolled nonspecific adsorption of proteins from the extracellular matrix results in interfaces with many types of proteins in different conformations—a situation that is believed to cause deleterious reactions of the body, such as foreign-body response and fibrous encapsulation. ... 

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