Opinion: Selecting a Pathogen Inactivation System

Transfusion-transmitted infectious disease are a continuing threat.  Despite donor infectious marker testing and new donor questioning, there are many threats which are not addressed by these measures.  Also new pathogens are being identified for which there are no tests or specific donor questions available.  How can we handle these new threats?

Pathogen inactivation can significantly reduce infectious agents in blood components, although the degree varies depends on the agent.  Theoretically any agent with nucleic acid—RNA or DNA is affected.  The only class of agents not affected at all are prions, which have NO nucleic acid at all.

In general, a photoactive agent is added to the blood component which binds to the nucleic acid.  Photoactive agents include riboflavin, psoralen dyes, and methylene blue.  Then the component is irradiated, the time proportional to the volume of the unit.

The component is then exposed to ultraviolet light to photoactivate it, which disrupts the DNA and RNA present, including in the white cells.  Thus, NO irradiation or bacterial culture is required.

Here are my questions to consider when selecting a pathogen inactivation system:

Targets?  Platelets vs plasma vs whole blood?

Methylene may be used for plasma, but riboflavin or psoralens may be used for platelets or plasma.  Whole blood inactivation with riboflavin is CE-approved.

Photoactive dye:  Is it riboflavin vs psoralen vs methylene based?

Riboflavin is vitamin B2—the amount used is small and does not need to be removed whereas the psoralen must be removed for clinical use.

Does the photoactive material need to be removed before transfusion?

You can immediately use the riboflavin-treated component but the psoralen must be removed before transfusion—this may take 6 or 20 hours depending on the licensing of the product.

What is the loss of platelets or coagulation factors after treatment?

With treatment by all methods, there is some loss of platelets and coagulation factors.  The platelet loss may be greater in psoralen-based methods and require additional components be added to the pool to reach the desired dose.  Likewise, plateletpheresis components treated with psoralen may require a recalibration of the donor apheresis equipment to collect more platelets per dose to compensate.  There may be some RBC loss additionally in whole blood pathogen inactivation.

What is the efficacy of pathogen reduction for the infectious agents, particularly the ones in your region?

Example:  How well does the treatment handle local agents like Hepatitis E?  Psoralen agents may be less effective than riboflavin for this agent.

Does it work with platelet additive solution PAS?

There are minimum and maximum volumes for pathogen inactivation set by the manufacturer.  Can you get sufficient yields within these volumes?

How good is the data management system?  Can it be integrated with your blood bank computer system?

Can the equipment be integrated with your system?  This is important to set rules and enforce good manufacturing processes GMP.

Does it work well with an automated blood component production system?

Such automated systems like the Reveos can free up personnel for pathogen inactivation.  Can the volumes produced be handled effectively by the pathogen-inactivation method?  Do the timings for separation of components work synergistically with the pathogen inactivation method?

Vendor issues:  how well will the local agent provide support?  Is someone else in your country or region using the system?

You need an experienced vendor to provide optimal support.

Automation and Synergism: Joint Use of Reveos and Mirasol

This is the virtual talk I gave at the Russian Transfusion Congress in Moscow on 13 May. It gives a brief description of automated component processing and riboflavin-based pathogen inactivation and then discusses the use of these technologies together to free up labor and enhance the quality of products, i.e. improved GMP, especially if a dedicated blood bank computer system is used to enforce production rules.

My Opinion: Issues in Transfusion Medicine Software and Component Production

I anticipate that there are several innovations coming or in the process of coming to mainstream blood component production and software.  Some of these I have already addressed in some of my previous posts:

Pathogen inactivation:  We have had this for over a decade.  However, with new emerging pathogens, this will become more important so I expect it will be adopted in many centers where it is not currently being used.  I expect we will close the loop and pathogen-inactivated RBCs will be available so all components will be treated.  Still, the first-generation pathogen-inactivated RBCs may have reduced shelf life compared to regular, untreated units.

Automated component production:  Although this is expensive, it does provide excellent GMP production.  It is fast and may provide higher yields, especially for platelets.  I expect more centers will adopt this technology, especially in combination with pathogen inactivation.

Blood bank computer software:  This software must be considered as dynamically changing, and considerable resources are needed to keep in compliance with ever-changing international regulations and the latest epidemiologic data.  Production rules can be strictly and mercilessly enforced by a dedicated blood bank computer software.  It can also ensure that the final ISBT label is not applied unless all the production rules (registration, collection, processing, and testing) are met.  Manual processing is extremely risky nowadays with all the parameters to be monitored.

Patient Blood Management:  Current blood bank software does not adequately address the need for prospective review of component orders.  I expect that collaboration will occur between laboratory and blood bank software vendors to fill this gap.

Refrigerated platelets:  The pendulum swings back to this component which was used over 40 years ago.  Refrigerated platelets suspended in additive solution may be effective up to 14 days for hemostasis in the trauma setting.  These platelets are activated so standard 20-24C stored platelets may be preferred for prophylactic transfusions.

Low-titer group A universal plasma:  This is already available, but its use will increase because of the low numbers of group AB units available and increased demand.  This includes its production for COVID convalescent plasma.  Your transfusion medical director must decide what “low titer” means.  Also you need a robust way of performing anti-B titers, this may require use of an immunohematology analyzer with titration built-in.

Low titer group O whole blood:  Use of this product may reduce the need for components in massive transfusion settings but it requires performing anti-A and anti-B titers on large numbers of units.  Your transfusion medical director must decide what “low titer” means.  Also you need a robust way of performing anti-A and anti-B titers, this may require use of an immunohematology analyzer with titration built-in.  Also, you must decide whether to leukodeplete the whole blood units:  few whole blood filters are platelet-sparing.

Reveos and Atreus Automated Blood Component Processing: My Experience

This post is about my over 10 years of experience with automated component processing using Terumo equipment, first Atreus and then Reveos at HMC Qatar.  The Reveos system is still in use at that institution.  There is also a previous post about Mirasol riboflavin-based pathogen inactivation.

We were the first place in the world to combine the automated component production Atreus with the Mirasol pathogen inactivation.  Their synergism was very important in the rapid throughput of component production for Qatar.

Terumo has two programs, 2C (C for components) to yield plasma and RBCs and 3C for yielding RBCs, plasma, and platelets.  The 2C program is faster but no platelets are separated.

We used the Atreus since 2010 and later replaced it with the Reveos in 2016.  Both systems use a special blood bag set that collects the whole blood in European CPD.  The kit is carefully placed in the machine.  Atreus machines accepted one blood bag set, the Reveos can accept up to 4 sets.  In both cases, the whole blood is processed to yield packed RBCs, leukoreduced plasma (<1E6 residual WBCs), platelets, and a special WBC bag (i.e. the residual buffy coat, which is not for clinical use.

The Atreus took about 10 minutes to process the one bag set whereas the Reveos processes 4 bag sets in slightly more than 20 minutes.  Thus, the throughput from the Reveos is twice that of Atreus.

We had 4 Atreus and later 4 Reveos machines and these were handled by up to 4 technologists, depending on the number of the units.  While the machines were running, the staff were filtering the RBCs and platelet pools, pooling the platelets, and performing the PAS-Mirasol pathogen inactivation.  The workflow was not hectic and staff were not stressed out by the multiple tasks.  Normally 1 staff member ran the Reveos or Atreus machines at any one time.

When the processing was complete, the RBC bags were filtered with an integral leukodepletion filter designed to leave a residual of <1E6 WBCs in accordance with the CE Standard.  The platelets were combined to give a target yield of >= 2.4E11 absolute number of platelets.  Then the pool was leukodepleted by filtration to a residual of <1E6 WBCs.

Both Reveos and Atreus measured the RBC, platelet, and plasma volume yields.  Additionally, for platelets a Platelet Yield Index PYI was calculated as a relative measure of the platelet yield.  To reach a goal of 2.4E11 platelets, the PYI indices for the individual platelet bags were added so that the total exceeded 240.

When combined with the Mirasol system, the component volumes for the plasma and platelets needed to be within specified ranges.  Both systems could easily meet these requirements.

When we switched from Atreus to Reveos, our platelet yields increased.  The transition period was only two weeks.   When we adopted platelet additive solution PAS at the same time, the Reveos had a special program to make “dry” platelets with less volume so that the PAS could be added and still stay within the acceptable range for pathogen-inactivation.

Throughout these years, Terumo sent us special engineers to handle the Atreus then Reveos, Mirasol, and PAS processing.  All staff were trained by Terumo initially before we finalized their competency assessments. 

We had excellent local service:  we never had downtimes due to equipment failures.  During the COVID pandemic, all materials (kits, filters, Mirasol solution, and PAS) have been provided without interruption.

We went live with Medinfo Hematos IIG software for the entire blood donor center and hospital blood banks in 2013.  From the first day 30/6/13 we had bidirectional interfaces first to the Atreus and later to the Reveos—the world’s first.  Likewise, the Mirasol and PAS processing were fully integrated with Medinfo when they were activated.

The residual buffy coat was not used for patient care.  However, it has proven invaluable as a quality control material for the stem cell laboratory.  In addition, many researchers have used it to establish cell lines for investigational use.

Proper handling the collected whole blood units is critical to success:

  1. Maintain the temperature below 25C.
  2. Carefully stack the whole blood units in the blood containers—do not play “ring toss” and just throw them into the container.

In summary, I am very pleased with using this system for over 10 years.  In a few weeks, the production laboratory was fully GMP compliant using a diverse group of staff with varying technical backgrounds.

The following are some pictures of the Reveos and its prepared blood components.

Reveos Machine has 4 chambers to process the 4 whole blood units.
Reveos takes up little space: this crowded corner processed all whole blood for Qatar.
Buffy-coat platelets processed by the Reveos
Close-up of Reveos buffy coat platelets: notice there are NO streaks of RBCs.

My Ten Years of Experience with Mirasol

I originally adopted this technology because of the plethora of new emerging pathogens.  In addition, I have been concerned about unknown pathogens that have not yet been discovered.  It is not what we know, it is what we don’t know that bothered me.

It is now 10 years since I started using riboflavin-based pathogen inactivation.  Our adoption of the technology was as follows:

  • 2010 pooled buffy coat and apheresis platelets, both suspended in plasma
  • 2012 whole-blood derived plasma and apheresis plasma
  • 2015 pooled buffy coat and apheresis platelets, both suspended in platelet additive solution PAS

Buffy coat platelet pools and whole-blood-derived plasma were both prepared with automated blood component technology, originally with the Terumo Atreus and later with Terumo Reveos system.  We were the first site worldwide to use automated production with the Mirasol system.

After 10 years and over 300,000 donor collections, no documented infectious agent transmission has been noted.  Our average platelet loss has been 4%.  There has been no increase in adverse reactions to plasma or platelets compared the time before we adopted these technologies.  Physicians accepted the products readily.

Mirasol adoption allowed us to discontinue irradiation of platelets and extend our outdate to 7 days.  We did not need a specific bacterial detection system.  Pending regulations in the USA will require stringent bacterial detection processes that are not necessary if a pathogen-inactivation system is being used.

Terumo sent its own engineers to set up and validate the system.  They also trained all the staff in the actual pathogen-inactivation processes and helped us to perform the validations.

When adopting pathogen inactivation, we compared Mirasol with its competitor and selected it for the following reasons:

  • Loss of platelets is low (about 4%)—lower than its competitor product.
  • There is no need to remove the riboflavin from the final product.

In our system, our goal was rapid processing of units.   With Mirasol, we did not have remove the riboflavin from the final product.  The competitor product requires at least 6 hours post-treatment to remove the psoralen agent.  We could immediately use the Mirasol product after treatment!

In our Reveos-Mirasol system, we can process whole blood into packed red cells in SAGM, buffy coat platelets, and plasma in a total of 5 hours including all testing with Mirasol treatment and platelet additive solution PAS.

We originally used the system manually, but in 2013, Terumo in conjunction with Medinfo Hematos IIG developed an interface to the Mirasol illuminator.  The latter device would transmit the successful completion of the illumination to the software.  Any errors in the illumination would block release of the blood component from Medinfo.  Medinfo also monitored the component volumes to prevent treatment of units outside Terumo’s recommendation ranges.

Adoption of platelet additive solution PAS gives us a final product with minimal residual plasma which potentially can reduce plasma reactions and TRALI/TACO.  It also minimizes our need to reduce the volume of platelet components for pediatric patients, especially in cases with ABO-incompatible plasma

Adopting any system of pathogen inactivation requires meticulous monitoring of component volumes to ensure they are within the range for the treatment.  The use of a blood bank software greatly facilitates this.

We make both buffy coat and apheresis platelets. The change from plasma-suspended to PAS-suspended platelets went smoothly.  Special training for Trima apheresis staff to use the new processes was provided by Terumo.

Throughout this time interval, Terumo has provided excellent technical support and educational activities for all staff.  Despite the COVID pandemic, Terumo has been able to deliver supplies to meet our needs so there was no interruption in production.

We started COVID convalescent plasma CCP production at the end of winter 2020.  We set up a parallel but separate quarantine system of collection and processing, originally manual but later controlled by the dedicated blood bank software Medinfo Hematos IIG.  All CCP units have been treated with Mirasol.

In the future, I hope Mirasol will close the loop by providing a pathogen-inactivation process for red blood cells so all components can be treated.  The CE mark for pathogen inactivation of whole blood is exciting and I hope that component preparation from this product will be offered.

In summary, our blood bank system had an excellent, synergistic relationship with Terumo and Medinfo to provide the highest quality product that is currently licensed.  I hope we will all continue to work together to improve the patient care.

International Perspective

When I first moved overseas from the United States, I brought the perspective of my American training and experience.  I saw everything in my new blood bank through those eyes.

Yet, most of my staff were not American or even North American.  Few were even native in English, and most of those  were not American.  They had different qualifications, many of which would not have been accepted by the American schemes.  Still, they functioned well.

I also worked with the US military technologist staff during Gulf War One.  Some did not even have a Bachelor’s degree;  yet, they performed the work well.

I used many technologies that were not yet (or never) US FDA approved such as gel or glass bead typings and pooled buffy coat platelet production.  There were rare reagents I could buy off the shelf (e.g. anti-Tja/PP1Pk).

Later, I adopted pathogen-reduction technology (Mirasol), automated component production (Atreus then Reveos), and platelet additive solution.  I achieve a level of good manufacturing practice that would have been difficult to achieve by the FDA-approved methods.

My perspective had changed.  In the Middle East, I studied many frameworks and came to the conclusion that the best approach was to customize them to our local needs.  My particular experience was to start with one framework, i.e. Council of Europe CE, and then localize it.

To do this, I could not use an American turnkey blood bank software for either the donor or patient operations.  I needed a flexible system that could be customized to my needs.  Again, I chose a CE-marked system, Medinfo Hematos IIG that had already been adapted to many frameworks.

It is much easier to work solely within one system such as FDA.  However, if I had done that, I would have lost so much flexibility and not had a system optimized for local conditions.  I would not have used Mirasol, Reveos, Diamed, and many other reagents.

One big disappointment at such international meetings is the perspective by one country’s regulatory agency that they feel its regulations and framework will work well overseas.  I would wager that those people were not well acquainted with international conditions.

Another frustration was attending another international meeting in which the presenters apologized for the source of information since it came from a foreign country (France) and not their own (United States).

No country has a monopoly on what is best for everyone.  To share our experiences and compare is so valuable.  No one assume his way is the best.  In my career, I have had the richest experiences studying other perspectives and my organizations have benefited greatly from the exchange.  We can all learn from each other.  We are citizens of the world.

Therapeutic Apheresis Volume Calculations

You can get the values off the therapeutic apheresis machine, but in the middle of the night when you have to write orders, it is convenient to estimate the volumes (whole blood, plasma, RBCs).  These are the values from my lectures to hematology fellows while I was at HMC Doha:

Whole Blood:

Weight in kg X 70 ml/kg = whole (whole) blood volume adult

Weight in kg X 85 ml/kg =whole blood volume for child (prepubertal)

Weight in kg X 100 ml/kg = whole blood volume for neonates/premature

Example:  70 kg adult has 4900 ml blood volume (I round up to 5 liters)

Plasmacrit + hematocrit = 1.00 in fractions (100%), ignore buffy coat volume

Plasmacrit = 1- hematocrit

Plasma volume:

Plasma volume = whole blood volume x plasmacrit = whole blood volume X (1-hematocrit)

RBC volume:

RBC volume = whole blood volume x hematocrit

Estimates for blood components:

The volumes will depend on the original amount collected (e.g. 450 vs 500 ml),  original preservative solution used (e.g. CPD), use of automated component production such as Terumo Atreus or Reveos, use of RBC additive solution (e.g. SAGM), leukodepletion, platelet additive solution, pathogen inactivation.

At HMC Doha, the average values were:

300 ml for leukodepleted RBCs in SAGM prepared by Reveos

300 ml for platelet pools in Mirasol and platelet additive solution (residual WBC < 1E6)

300 ml for plateletpheresis concentrate (2.4E11) in Mirasol and platelet additive solution

250 ml for leukodepleted, pathogen inactivated plasma