Transplantation and Tissue Engineering Quiz

Wound Terminology

• Synthetic Materials: Derived from non-living sources (metals, ceramics, polymers).

• Biologic Materials: Derived from living organisms (humans, animals, cells).

• Autograft: Tissue transplanted within the same individual (e.g., bone-tendon-bone from right knee to fix a torn left ACL).

• Allograft: Tissue transplanted from one individual of one species to a different individual of the same species (e.g., donated human tissue, bone-tendon-bone, used to repair a torn ACL). Dermacell is one example of an allograft.

• Xenograft: Tissue transplanted from one species to another (e.g., porcine [pig] heart valve to a human).

Tissue Processing - Relevant Terms

• Freeze-Dried: A hydrated substance frozen and all water removed by vacuum without thawing.

• Cryopreserved: Tissue frozen at a controlled rate with cryo-protectants to maintain viability and matrix integrity.

• Hydrated: A substance ready for use without rehydration—Dermacell is fully hydrated upon packaging.

• Aseptic Processing: Technique for cleaning and shaping donor tissue/products in a clean room environment to minimize contamination.

• Shelf Life: Validated length of time a product can be stored after sterilization or aseptic processing.

• Sterility Assurance Level (SAL): Probability of a single viable microorganism being present on a product. 10⁻³ (1 in 1000) and 10⁻⁶ (1 in 1,000,000) are common levels.

• Terminal Sterilization: The process of sterilizing a material in final packaging. (Dermacell is terminally sterilized using low dose gamma irradiation at ultra-low temperatures to achieve a SAL of 10⁻⁶).

###Tissue Processing - Relevant Terms (cont.)

• Decellularization: Process of removing cells and cellular debris from tissues to potentially reduce immunological reactions. Dermacell is decellularized using Matracell technology.

• Immunological Reaction/Response: A bodily response to an antigen triggered when lymphocytes identify the antigen as foreign, leading to antibody and lymphocyte production to neutralize the antigen.

Wound Healing - Relevant Terms

• Scaffold: A biocompatible material matrix that allows host tissue cells to grow and repair/replace damaged tissue.

Wound Healing - Relevant Terms (cont.)

• Type I Collagen: Found in bone, tendon, ligament, skin, blood vessels, cornea, heart valves.

• Type II Collagen: Found in cartilage and intervertebral discs.

• Type III Collagen: Found in blood vessels, fetal skin, heart valves.

Wound Healing - Relevant Terms (cont.)

• Enzyme: Protein that catalyzes a biochemical reaction without being modified.

• Collagenase: Specific enzyme that breaks down collagen.

• Tissue Digestion: Mechanism for breaking down dead and/or damaged tissue via enzymatic degradation.

Wound Healing Process Terminology

• Biohospitable: Biocompatible material that does not cause an inflammatory or adverse response from the recipient, facilitates cellular infiltration and replication, and promotes constructive remodeling of the implant site (e.g., collagen, elastin, smooth muscle actin).

• Inflammation: Local response to cellular injury, marked by capillary dilation, leukocyte infiltration. It serves as a mechanism to eliminate harmful agents and damaged tissue.

• Scar Tissue: Connective tissue forming a scar; primarily made of fibroblasts in recent scars and dense collagenous fibers in older scars.

• Resorption (Reabsorption): Destruction, disappearance, or dissolution of tissue/part by biochemical activity.

• Remodeling: Process of building and resorbing tissue.

Wound Healing Process Terminology (cont.)

• Revitalization: Tissue graft revitalization (repopulation and vascularization) upon placement within a surgical site. It is aided by the graft's stability (resistance to enzymatic breakdown), lack of prolonged inflammation, and biocompatibility with the implant.

Other Contributors to Wound Healing

• Matrix Metalloproteinases (MMPs): Enzymes that assist in protein breakdown within the extracellular matrix in a wound site.

• Cytokines: Proteins involved in cell signaling during inflammatory/remodeling phases of wound healing.

• Growth Factors: Proteins involved in cell signaling that drive cell migration, division, protein expression, and differentiation during wound healing.

• DNA Residuals: DNA remaining after decellularization, reduced to <97% in Dermacell following Matracell technology.

• Macrophage: "Scavenger" cells for removing particulates/biologic debris—aid in remodeling stage of wound healing M1 (janitors) assisting in the removal of debris, followed by M2 (construction workers). Dermacell demonstrates a "more constructive" mix of M1 and M2.

• Giant Cell: Multiple macrophages merging to engulf large particles and implants.

• Neutrophil: Multi-nucleated cells frequently seen in infections, participating in the early stages of normal inflammatory response during wound healing.

Other Contributors to Wound Healing (cont.)

• Lymphocyte: A type of white blood cell that identifies and targets antigens during an immunological response.

• Fibroblast: Connective tissue cell responsible for collagen and other fiber production.