Introduction to Allografts
What is an Allograft?
An allograft is a tissue transplant between genetically dissimilar members of the same species1. An allograft is different from an autograft, which utilizes tissue from the same individual’s body and is therefore genetically identical. Examples of human allografts include: anterior tibialis tendon, frozen femoral head, freeze dried bone chips, DBM putty, acellular dermis, and amniotic membrane.
What are the Sources of Allografts?
Allografts are made possible through the generous gift of tissue donation after death by individual donors and through family consent. They are obtained after the donor’s death by procurement teams with specialized training in anatomy and surgical techniques to ensure viable soft tissue and bone grafts.
How are they Regulated?
Human tissue products are regulated by the FDA. Most allografts are regulated as Human Cell and Tissue Products (361 HCT/P’s). To qualify as 361 HCT/P, allografts must be considered “minimally manipulated” according to specific criteria under Part 21 CFR 1271.10(a) of the Public Services Health Act.
Allografts that qualify as minimally manipulated human cells and tissues are not required to undergo the same regulatory approval processes as those allografts that are considered medical devices. Examples of 361 HCT/P allografts include the tendon, femoral head, bone chips, dermis, and amniotic membrane mentioned above, but not the DBM putty.
When a tissue product is combined with a carrier, filler, polymer, or other non-human or synthetic ingredient, the combined product is considered more than minimally manipulated by the FDA. These products must obtain FDA 510K Clearance and premarket approval (PMA) like other medical devices. This approval process requires a preclinical study (using animal models) to demonstrate the safety, effectiveness, and equivalence to a similar product already on the market. Examples of allografts that are regulated as medical devices are DBM putties, which combine demineralized bone matrix with bovine or porcine material, or with non-tissue carriers such as carboxymethylcellulose, glycerol, or hyaluronic acid.
What are the Surgical Uses of Allografts?
Allografts are used for the repair, reconstruction, supplementation, or replacement of a recipient’s cells and tissues. For allografts to qualify as 361 HCT/P’s according to the FDA, the human cell or tissue product must perform the same basic function or set of functions in the recipient as in the donor, also known as “homologous use.” For example, tendons used for ACL reconstruction act as a connector in the recipient, as they did in the donor; connecting muscles to bones in the case of tendons is homologous to the function of connecting two bones, as ligaments do. In the same way, acellular dermis used for breast reconstruction acts as a soft tissue replacement, maintaining the same basic function as the original donor tissue.
Each year there are more than 1.75 million allografts performed in the United States from more than 30,000 donors.2 Since allografts were adopted into modern medicine 150 years ago, they have found increasing and widespread usage in a variety of medical fields, improving surgical outcomes and the quality of life of patients.
Tissue Banks
Tissue banks play a vital role, making it possible to perform life-saving, function-preserving medical transplants. Charged with qualifying donors and preparing and processing tissues for transplant, tissue banks must operate in a way that ensures the quality and safety of allografts.
But how do you know if you are working with a quality tissue bank? How can you tell if your tissue bank is adhering to the industry’s highest standards? What are some of those standards?
Get the answers in this post: Tissue Banks: Standards and Accreditation
