Tissue Processing & Preservation Flashcards

What is the functional difference between 'fresh' and 'fresh-frozen' allograft bone regarding osteoinductivity?

Answer: Fresh bone retains more viable cells and growth factors; fresh-frozen loses some bioactivity but retains structural properties

Fresh bone retains living osteoblasts and higher concentrations of growth factors, while freezing partially denatures proteins and kills cells though structural integrity is largely preserved.

A processing technician inadvertently leaves a skin allograft at 4°C for 72 hours in nutrient media. Which microorganism is of GREATEST concern regarding overgrowth during this period?

Answer: Pseudomonas aeruginosa

Pseudomonas aeruginosa is a psychrotolerant gram-negative bacterium that can proliferate at refrigerator temperatures, posing the greatest risk during prolonged cold storage.

Which statement BEST describes the role of sucrose in cardiac valve cryopreservation media?

Answer: It acts as an extracellular impermeant to reduce osmotic cell swelling

Sucrose is a large molecule that does not cross cell membranes; it raises extracellular osmolality to counteract osmotic swelling caused by cryoprotectant-induced cell shrinkage.

Which processing step is UNIQUE to the preparation of demineralized bone matrix (DBM) compared to standard cortical bone processing?

Answer: Acid demineralization (typically in 0.5N HCl)

DBM production requires an acid demineralization step (commonly 0.5N HCl) to dissolve the mineral hydroxyapatite and expose the collagen and growth factor matrix.

In tissue banking, what is the significance of the 'D-value' (decimal reduction value) when validating a sterilization process?

Answer: The time or dose required to reduce the microbial population by 90% (one log)

The D-value represents the time or dose needed to kill 90% of a test organism population under defined conditions, forming the basis for sterilization cycle validation.

What AATB requirement governs the handling of tissues when the monitored storage temperature is found to have exceeded its validated range?

Answer: A documented deviation investigation must be performed and the tissue quarantined pending review

AATB standards require a formal deviation investigation and quarantine; the tissue disposition is determined by the outcome of the investigation, not automatic discard or release.

Which structural feature of cortical bone makes it more resistant to cryoprotectant penetration compared to cancellous bone?

Answer: Dense, low-porosity Haversian system with minimal interconnected channels

Cortical bone's dense Haversian system with small, poorly interconnected channels severely limits the diffusion of cryoprotectant solutions into the tissue interior.