BB Lec - Current Trends Flashcards
Creating RBCs in the laboratory
(blood pharming)
mechanism for forming O-type RBCs
The use of enzymes that remove the carbohydrate moieties of the A and B antigens
Current research on blood substitutes is focused on two areas:
hemoglobin-based oxygen carriers (HBOCs) and per- fluorocarbons (PFCs)
Originally developed to be used in trauma situations such as accidents, combat, and surgery,
RBC substitutes
are intimately involved in primary hemostasis,
Platelets
interaction of platelets and the vascular endothelium in halting and preventing bleeding following vascular injury.
hemostasis
cellular fragments derived from the cytoplasm of megakaryocytes present in the bone marrow.
Platelets
They do not contain a nucleus
Platelets
platelet DNA found in__
mitochondria
average diameter of platelets
2 to 4 μm
normal plt count
150,000 to 350,000 per μL
how many days do PLT circulate
9-12 days
how much plt is sequestered in the microvasculature of the spleen as functional reserves.
30% of the platelets
Used to treat bleeding as associated with thrombocytopenia
PLT
Efficacy of transfused platelets: estimated from __
CORRECTED COUNT INCREMENT
CORRECTED COUNT INCREMENT estimates what of platelets?
Efficacy of transfused platelets:
measured after transfusion; does not evaluate or assess the function of the transfused plt
CCI
Transfused prophylactically to increase the circulating platelet count in hematology-oncology thrombocytopenic patients to prevent bleeding secondary to drug or radiation therapy
PLT
utilized in some instances to treat other disorders in w/c platelets are qualitatively or quantitatively defective because of genetic reasons
PLT
MAJOR PROBLEM whenplatelet transfusions were given as freshly drawn whole blood or platelet-rich plasma
circulatory overload
Today, platelets are prepared as (2)
concentrates from whole blood
by apheresis
The 2007 National Blood Collection and Utilization Survey found that only ??% of platelet doses in the United States were whole blood derived (WBD).
17
still remain as the primary means of treating thrombocytopenia
Platelets
Storage limit of PLT
5 DAYS
The two main reasons for the 5-day shelf-life for platelets are
> bacterial contamination at incubation of 22°C
>loss of platelet quality during storage (known as the platelet storage lesion
loss of plt quality and viability
Plt storage lesion:
assoc with loss of membrane integrity
Absence of platelet swirling:
During the storage of PCs in plasma, the principal buffer is
bicarbonate
PLT routinely stored at what temp with continuous agitation (primarily flatbed and circular agitators for up to 5 days).
20°C to 24°C,
In the United States, platelets are being stored WHERE, unless a platelet additive solution is used.
in a 100% plasma medium
Initially, platelets were stored at ___, based on the successful storage of RBCs at this temperature range
1°C to 6°C
what happens to PLT when stored at 1-6C?
becomes spherical from discoid
loss of PLT shape at 1-6c is due to
microtubule assembly
a study by _______ showed that cold storage at 1°C to 6°C resulted in a marked reduction in platelet in vivo viability, manifested as a reduction in in vivo life span, after only 18 hours of storage. This study also identified for the first time that 20°C to 24°C (room temperature) should be the preferred range, based on viability results.
Murphy and Gardner
aside from the temp considerations, platelets must also be ___ during storage
agitated
has been shown to facilitate oxygen transfer into the platelet bag and oxygen consumption by the platelets.
agitation
what happens when pH was reduced from 6.8 to 6.2
platelets progressively changed shape from disks to spheres
The ___ being used for storage were identified as being responsible for the fall in pH because of their limiting gas transfer properties for oxygen and carbon dioxide
containers
1st generation containers
polyvinyl chloride (PVC) containing phthalate plasticizer
2nd gen containers
PVC or polyolefin plastic
For most PVC containers,_____ used to increase gas transport
alternative plasticizers
two alternative plasticizers
trimellitate & citrate based a
____ is determined by measuring pre-transfusion and post-transfusion platelet counts (1 hour and/or 24 hours) and expressing the difference based on the number of platelets transfused (corrected count increment)
Platelet viability
The observation of the ____ caused by discoid platelets when placed in front of a light source has been used to obtain a semi-qualitative evaluation of the retention of platelet viability properties in stored units
swirling phenomenon
indicates the capacity of platelets to circulate after infusion without premature removal or destruction.
Viability
Platelets have a life span of ??days after release from megakaryocytes.
8 to 10
is defined as the ability of viable platelets to respond to vascular damage in promoting hemostasis.
Function
The major concern associated with storage of platelets at 20°C to 24°C is the ?
potential for bacterial growth
Company developing the technology of blood typeconversion
ZymeQuest
Company awarded the contract to develop a system to produce O negative RBCs
Arteriocyte
Blood substitutes areas of research
Hemoglobin-based oxygen carriers
Perfluorocarbons (PFCs)
How much platelet is discarded by blood supplier or hospital blood bank
Approx 30% of platelet inventory
Identified as being responsible for the fall of pH of PLT due to their limiting gas transfer properties for oxyen and carbon dioxide
Containers for storage
Disadvantages of culture methods for detection of bacterial contamination of PLT
Product loss due to sampling
False negative results
Costs
Delay in product release, further reducing already short shelf-life
Logistical problems of culturing WBD platelets
