Platelet Concentrate, How to Maintain Quality

The new discussion on the Blood Components group at LinkedIn on producing good quality platelet concentrates (PLT) is of very great importance. PLT is considered something of a mystery to many blood bankers and with good reason. I thought of sharing a few tips here in support of this discussion.

In the first place, there are so many methods of making PLT (see the previous post). But, that's only the beginning of the confusion. Many manufacturers the world over make blood bank centrifuges. Each manufacturer offers a number of different rotors - 4, 6, 8, and 12 place rotors are all fairly common. In each case, the way the individual centrifuge spins its rotor (the g profile) is different. So, making random donor platelets (the commonest procedure) varies widely from blood bank to blood bank. In general, though, for the first spin (platelet rich plasma or PRP method) we need to keep the g under 1000 to ensure that the g force itself does the least damage to the PLT. In each case, for a given g force, the spin time will vary. Some centrifuges have advanced braking systems, so the time to a complete stop after the spin is lessened. In other cases one has to wait patiently for the rotor to come to a complete halt.

Removing the blood bags from the centrifuge smoothly and without shake is of very great importance. Be sure to give your techs plenty of hands on training before allowing them to work with 'real' blood components. Contamination of the PLT with RBCs and with buffy-coat elements has to be minimized. Then, the technicians have to be very careful when expressing the PRP into the satelite bags not to attempt to take too much buffy-coat so as to avoid RBC contamination. Ideally a PLT of 50 to 70 mL should have less than 0.5 mL of RBC in it. The second spin yields the platelet concentrate (PLT) and platelet poor plasma. In this spin, again the g force needs to be kept as low as possible but should yield a good button of platelets which then have to be left for a short time to rest before resuspension. It's best to use a weighing device to precisely leave 50 mL (sometimes 70 mL) of plasma behind in the3 PLT bag.

For storage over 2 days, special plastic must be used which breathes and allows a high enough O2 concentration to maintain the pH in an ideal range. In situations like dengue hemorrhagic fever, or with directed donations (say for patients on chemo) where the platelets will be used within 48 hours, a lot of money can be saved for the patients by using 'ordinary' plastic double or triple bags.

At this stage, once the rest period is over, the PLT should SWIRL. this is of critical importance. Hold the PLT bag up to the light and look for the swirl. If it's not there after 2-4 hours of rest, that PLT unit should be discarded!

Some blood banks use the buffy-coat method, and here a short very hard spin is first used to produce RBC with platelets and leaving the majority of the white cells in the platelet poor plasma layer. Then a soft spin of the RBC yields the platelets in the buffy coat. This procedure, using a top and bottom bag, is common in the US. These bags are costlier and the pooling  of buffy-coats that is usually required involves the use of SCDs, but when a leukocyte filter is included you do end up with an excellent product and still less costly than when using an apheresis (cell separator) technique.

These are some basic points that I have found useful. It is a deep and fascinating subject, and I am sure that many of you may have some points to add. Comment below, or even better, submit a separate write up for publication here.

ClinLab Navigator has a short recent (2012) summary: http://www.clinlabnavigator.com/platelet-concentrates.html?letter=P

Towards targeting platelet storage lesion-related signaling pathways  Blood Transfusion 2010 June; 8(Suppl 3): s69–s72.  Peter Schubert and Dana V. Devine

Evidence-Based Platelet Transfusion Guidelines  HEMATOLOGY: January 1, 2007 vol. 2007 no. 1 172-178 Sherrill J. Slichter, MD, Director, Platelet Transfusion Research, Puget Sound Blood Center, 921 Terry Avenue, Seattle, WA 98104-1256; phone (206) 292-6541; fax (206) 292-8030; sjslichter@psbc.org

In vitro assessment of platelet storage lesion in leucoreduced random donor platelet concentrates  Blood Transfusion 2010 January; 8(1): 28–35. Amal S. Ahmed, Ola Leheta, and Soha Younes

2 videos that demo the platelet swirl:

Abstracts:

Past and future approaches to assess the quality of platelets for transfusion.  
Transfusion Medicine Review. 2007 Oct;21(4):295-306.  
Maurer-Spurej E, Chipperfield K.  emaurer@interchange.ubc.ca

Suitability of measurement of swirling as a marker of platelet shape change in concentrates
 stored for transfusion.  
Platelets. 2006 Sep;17(6):393-6.  
Mathai J, Resmi KR, Sulochana PV, Sathyabhama S, Baby Saritha G, Krishnan LK.  jaisym@sctimst.ker.nic.in

Platelet Concentrate Preparations, Brief Comparison

When platelets are in demand, the options are:

1. Random Donor Platelets RDPc.
2. Single Donor Platelets SDPc-A (automated apheresis or cell separator processed)
3. Single Donor Platelets SDPc-M (manual apheresis)
4. Pooled Buffy Coat Platelets (PBCPc)

There is little doubt that quality-wise the Single Donor Platelet concentrates win hands down over the other options both for quality of product and safety. However, in the automated process (using cell separators) cost can be a major inhibiting factor, especially in developing countries. Now, with the US dollar on the rise against most currencies, this becomes an even bigger problem as both the equipment and the single use disposables costs have jumped upwards between 15% to 20% just over the last 6 months. In Pakistan a kit can cost 15,000, while in India it's typically 12,000, for one popular brand.

Manually processed single donor platelets are now a good option to explore. Of course, it is as time consuming (and labor intensive) as the automated process, and the most platelets one can hope to harvest will be equivalent to 2 RDPc at one donor sitting. Still, the safety of the single donor approach is maintained, and costs can come down to INR 500 to 1,000 for these 2 units together (depending on the pricing structure for platelets) as it only requires the use of 2 double bags per session, and double bags are relatively inexpensive. [Of course, as the platelets are collected in 'ordinary' double bags, there is no question of storing for longer than a day. It is a major factor in significantly reducing the cost. A note added after the initial posting]

For diseases like dengue where pediatric cases are more common, SDPc-M (harvesting 2 RDPc units worth of platelets a day) can be more than sufficient to maintain minimum platelet counts, while harvesting a lot of platelets SDPc-A (using a cell separator) may lead to a lot of wastage and may compromise the donors' abilities to maintain healthy platelet counts over the period of 1-2 weeks when the disease is at its most critical.

	Platelet Concentrate Product	Total Plt Counts	Typical Volume	Plt/mL	Typical Process
1	Random Donor Platelets RDPc	4.5x10(10) or 45x10(9)	50 mL to 70 mL	6.5x10(8)	Manual, triple bags
2	Single Donor Platelets SDPc-A	3x10(11) or 300x10(9)	300 ml	1x10(9)	Automated apheresis/cell separator
3	Single Donor Platelets SDPc-M 2 units	9x10(10) or 90x10(9)	100 mL	9x10(8)	Manual, double bags
4	Pooled Buffy Coat Platelets PBCPc Plt from 4 units + 1 unit plasma	1.8x10(11) or 180x10(9)	250 mL	8.8x10(8)	Manual, 'top and bottom' bags

Comments please!

Some References:

1. Buffy-coat-derived pooled platelet concentrates and apheresis platelet concentrates: which product type should be preferred?  

H. Schrezenmeier, 

E. Seifried 

Vox Sanguinis 

Volume 99, Issue 1,  pages 1–15, July 2010 

2. Storage of Apheresis and Pooled Buffy-Coat Platelet Concentrates Treated 

with Pathogen Inactivation Using the INTERCEPT Blood System Peter Schlenke, Valentine Franck, Lily Lin, Holger Kirchner Presented at the XXIX International Congress of the 

International Society of Blood Transfusion (ISBT) September 2-7, 2006 http://www.interceptbloodsystem.com/poster_pdfs_2006/ISBT-2006_Schlenke.pdf

3. Canadian Blood Services Transfusionmedicine.ca Vein to Vein: Preparation of Platelets (online)

http://www.transfusionmedicine.ca/resources/books/vein-vein/donations/component-preparation/preparation-platelets

The Blood Components Group Blog

Welcome to the Blood Components Group! The group aims to promote blood component use particularly in developing nations - where far too much whole blood is being prescribed. This battle has been fought and won in the developed nations, but has to be again fought and won in the developing world! Welcome to the battle and we look forward to your contributions.

We're going to start out at LinkedIn with a discussion on platelet concentrates and the possibilities of using a manual 'apheresis' method instead of the much more expensive automated apheresis that has been touted by some as a solution. Visit the LinkedIn group for the main discussion, and do join the group if you haven't already.

I hope to see many other discussions started by group members as we collectively try to make blood component therapy the norm rather than the exception in the developing world.

Blood Component Group members Please submit any potential articles or documents that you want to share/display here in this blog (in Word) to my personal email samlcarr@gmail.com and I will screen and post them to the blog. I'm right now working alone on this, but promise to get it done as soon as possible.