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Where does bone come from when they say I'll get donor tissue from the bone bank? And what's an allograft?

Many types of tissues and organs can be donated and therefore transplanted. Tissue transplants include the heart, lungs, liver, pancreas, kidneys, intestines, skin, bone and bone marrow, umbilical cord blood, veins, soft tissues, heart valves, corneas, and eyes. There are different types of tissue transplants. Allograft (also known as a homograft) transplant occurs between individuals of the same species (e.g., human to human). Autologous transplants are within the same individual (e.g., skin graft from leg to hand; blood or bone marrow for own use later). Xenogeneic (heterograft) transplants are between individuals of different species (e.g., pig to human). Human allograft donor tissue is recovered from bodies after death in operating rooms, hospitals, morgues, and funeral homes. There are guidelines for when and how this is done. But there have been some problems with contaminated tissue. The adverse effects on the patient receiving the donated tissue can be severe (even life-threatening). For this reason, scientists are working to create bioengineered skin, bone, ligaments, tendons, and articular cartilage. These are already available in some clinical settings. For example, in some cases, it is possible for the surgeon to take healthy plugs of bone (or cartilage) from one site, multiply the cells in culture, and later place them into a lesion or hole in the same patient. This stimulates new, healthy bone to form and fill in the defect. Getting the bone up to the strength needed to bear full loads remains a challenge. Developing bone substitutes may be a way around this. A variety of materials such as natural and synthetic polymers, ceramics, and composites are under investigation. In order to make this work, growth factors, proteins, and other materials needed for bone healing must be present. These substances must be removed from healthy bone and mixed with the bone substitute in order to stimulate the formation of new bone cells.

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