Replacement body parts

The collection of stories that involve tissue engineering concepts shows the promise and spectacular possibilities that the future could bring. However, rarely do these stories fully conceptualize or even mention the challenges involved in performing these acts in reality. Until the advancement of tissue engineering in the 1970s, replacements for bodily tissues were prostheses made of wood, ceramics, and plastics. Replaced body parts included arms, legs, eyes, ears, teeth, and noses. 

Zip-lock bags, carrier bags, microwave-safe shrinkwrap food film, Tupperware containers, food chopping boards, food packaging films, milk, bread and beer crates, water pipes, electrical cable insulation, geo-textiles, replacement body parts (e.g. heart valves, artificial arteries, hip Joints). ... 

Polymers may be used in medicine either as biomaterials to support or replace body parts, or as pharmaceuticals, for use as drugs or in drug formulations. The biomaterial field is beyond the scope of this discussion and we will restrict our discussion only to the propa-ties of polysaccharides of biomedical interest and chemical methods available for their synthesis. At the present time only natural polysaccharides and their derivatives have been used medicinally but for some applications in physiology and internal medicine, synthetic polysacdiarides might be valuable. At last a few methods for their synthesis are available or in process of development. Some possibilities for the use of other synthetic polymers in medicine may also be suggested by the following survey. 

Synthetic materials utilized in medical devices are mainly composed of metals, ceramics, polymers, or a combination of these. In general, metals and ceramics are used to replace body parts that endure high loads, such as bone and teeth, and polymers replace all other body parts. Polymers offer many significant advantages (1) they are easy to mold into various shapes, including particle, film, and fiber (2) their chemical and physical properties are varied and controllable and (3) most body parts, other than lipids and hard tissues such as bone and teeth, are composed of polymers. Therefore, from ex vivo to in vivo materials, polymers are widely used for medical applications. Table 11.1 shows examples of medical devices composed of synthetic polymers [2]. 

Stem Ceii Therapy With stem cell therapy, the aim is to grow body parts to replace defective human organs and nerves. The stem cells are harvested from... 

Part 2 Materials for Replacing Human Body Parts... 

Another important area of materials development is related to the life sciences and concerns the development of materials to serve as replacements for body parts. There are challenges in replacing hard tissues such as hip and knee joints as well as soft tissues such as vascular tissue and ligaments. These implants will require very sophisticated composite materials if they are to model the properties of living tissues successfully. 

There are countless applications possible. Nowadays, it is possible to replace human parts with synthetic materials virtually anywhere in the body. Table 11.6.1 lists a number of examples of plastic and metal implants. Ceramic implants are not mentioned here because they will be discussed elaborately in this chapter. 

Technologies to preserve tissues and organs for transplantation and prevent tissue and organ rejection and for improvement of artificial organs and prostheses for replacing malfunctioning body parts should be identified.57 58... 

The important theme in all of these definitions is the desire of the drafters to move away from the use of donor or artificial organs or tissues as replacement for damaged body parts and explore mechanisms hy which the body can he encouraged to heal itself. This theme is reflected in two terms sometimes used as synonyms for tissue engineering regenerative medicine and reparative biology. 

Successes achieved in the young science of tissue engineering have encouraged researchers to consider the possibility of wholesale replacement of a number of body parts. For example, Ioannis Yannas s... 

Researchers have made amazing progress in the development of materials and structures for the replacement of nearly every possible body part. In most cases, however, those developments have been limited thus far to experimental use in a relatively small number of cases. A number of technical problems remain to be solved before engineered materials become reliable and inexpensive enough to be used commonly for the repair and replacement of structures damaged by injury and disease. 

The core of a taxidermy specimen may contain wire, soft wood, and stuffing material, with the skin stretched over it and sewn together. The stuffing can be just about anything. Straw and excelsior were common, but other plant materials or hair have also been used. Taxidermists who need to make mounts of similar animals repeatedly often create body casts in plaster from a mold that can be reused. Modem taxidermists often use pre-cast body molds made of plastic, wood, fiberglass, or compressed paper. The nose, eyes, and other elements of the outer body that were, in life, composed of soft tissue are usually replaced by replicas made of glass, wax, plastic, or resin. Paint and resin or lacquer may have been applied to various areas of the body in an effort to produce a natural color, or to protect the skin. Taxidermy mounts may contain screws, tacks, or bits of wire inside, as part of the frame, and at the surface where they are used to hold various body parts in place, like hooves, andeis, or hom sheaths. 

The use of aluminum in the automobile industry is steadily increasing. The replacement of steel permits a decrease in fuel consumption of the vehicles due to weight reduction. In the car industry, aluminum is mainly used in body parts, starters, generators, compressors, admission pipes, oil vats, gearbox housings, cylinder heads, and even engine blocks. 

Many uses of platinum depend on its chemical inactivity. For example, some people need to have artificial heart pacemakers implanted into their chests. An artificial pacemaker is a device that makes sure the heart beats in a regular pattern. It usually replaces a body part that performs that function but has been damaged. Artificial pacemakers are usually... 

Polyester-based resins are also used in bulk plastics in fiberglass reinforced fabrications such as boats, auto body repairs, and for very large structures such as industrial vessels and pipes, and ships for mine sweeping [10]. This technology uses a combination of polycondensation and vinyl-type (chain reaction) technologies to obtain the final composite product. The viscous, still fluid resin used for layup is a linear unsaturated polyester of relatively low-molecular weight. Unsaturation is introduced into the backbone of the polymer by using maleic anhydride to replace a part of the phthalic anhydride (e.g., Eq. 21.4). 

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