Cord Blood Cord Blood Collection and Processing 2 — Questions and Answers
Question 1: What is DMSO (dimethyl sulfoxide) used for in cord blood cryopreservation?
- As an anticoagulant during collection
- As a cryoprotectant to prevent ice crystal formation that would destroy cells during freezing (Correct answer)
- As a nutrient medium for cell growth
- As a red blood cell lysing agent
Correct answer: As a cryoprotectant to prevent ice crystal formation that would destroy cells during freezing
DMSO penetrates cell membranes and prevents ice crystal formation during the freezing process, protecting cord blood cells from cryogenic damage.
Question 2: At what temperature is cord blood stored for long-term cryogenic banking?
- −20°C (standard freezer temperature)
- −80°C (ultra-low freezer)
- −196°C (liquid nitrogen vapor phase) (Correct answer)
- 0°C (ice water)
Correct answer: −196°C (liquid nitrogen vapor phase)
Cord blood is stored at −196°C in liquid nitrogen vapor phase, which halts all biological processes and allows indefinite preservation of cell viability.
Question 3: What quality control test measures the ability of cord blood progenitor cells to form colonies and predicts engraftment potential?
- HLA typing
- Colony-forming unit (CFU) assay (Correct answer)
- Sterility culture
- DMSO toxicity test
Correct answer: Colony-forming unit (CFU) assay
The CFU assay cultures cord blood cells in semi-solid media to count the number of colonies formed by progenitor cells, serving as a functional measure of the unit's engraftment potential.
Question 4: Why is ABO blood group typing performed on cord blood units during processing?
- ABO type must match perfectly or the unit cannot be used
- ABO data is recorded for recipient safety during infusion and for post-transplant red cell monitoring (Correct answer)
- ABO mismatch causes immediate rejection of cord blood
- ABO testing is required only for private banks
Correct answer: ABO data is recorded for recipient safety during infusion and for post-transplant red cell monitoring
ABO blood type is recorded to alert transplant teams, as ABO-mismatched units may cause hemolytic reactions and affect post-transplant red cell chimerism monitoring.
Question 5: What infectious disease screening tests are mandatorily performed on the maternal blood sample associated with a cord blood donation?
- Only HIV testing
- Testing for HIV, hepatitis B, hepatitis C, HTLV, syphilis, CMV, and other infectious markers (Correct answer)
- Only a complete blood count
- Only bacterial blood cultures
Correct answer: Testing for HIV, hepatitis B, hepatitis C, HTLV, syphilis, CMV, and other infectious markers
Maternal blood is tested for a comprehensive panel of infectious diseases including HIV-1/2, HBV, HCV, HTLV-I/II, syphilis, CMV, and West Nile virus per FDA and AABB requirements.
Question 6: What is the purpose of controlled-rate freezing in cord blood cryopreservation?
- To heat-sterilize the cord blood unit
- To slowly lower the temperature at a controlled rate (typically −1°C/min) to minimize cellular damage during freezing (Correct answer)
- To rapidly freeze the unit in liquid nitrogen immediately after collection
- To test DMSO toxicity at different temperatures
Correct answer: To slowly lower the temperature at a controlled rate (typically −1°C/min) to minimize cellular damage during freezing
Controlled-rate freezing gradually lowers temperature to allow orderly ice crystal formation outside cells and DMSO to protect intracellular structures, minimizing cell damage during cryopreservation.
Cord Blood Cord Blood Collection and Processing 2
What is DMSO (dimethyl sulfoxide) used for in cord blood cryopreservation?