(P-CB-1) Development of a novel method using CD36-deficient platelets to measure the recovery and survival of transfused platelets in vivo

Sunday, October 20, 2024

12:00 PM - 1:00 PM

Presenting Author(s)

MN

Masayuki Nogawa, Ph.D

Research and Development Department, Central Blood Institute, Blood Service Headquarters, Japanese Red Cross Society
koto-ku, Tokyo, Japan

Background/Case Studies: Labeling of platelets (PLTs) with radioisotopes is the standard method to measure the recovery and survival of transfused PLTs in vivo. However, transfusion of radiolabeled PLTs is challenging because of safety issues and their highly restricted use, especially in Japan. We aim to develop a novel method in which PLTs derived from CD36-deficient donors (CD36^- PLTs) are administered to CD36-positive (CD36⁺) recipients. In current clinical practice, CD36^-PLTs, found in 3~5 % of the Japanese population, are used safely for PLT transfusion therapy without distinguishing them from CD36⁺ PLTs. For our new method, however, it is important to confirm that the functions of both PLTs are equivalent.

Study

Design/Methods: Human CD36⁺ and CD36^- PLT components (ABO identical) collected on the same day were subjected to in vitro assays on days 1, 3, and 7 of storage. On days 3 and 7 of storage, CD36⁺ and CD36^- PLTs were mixed at a ratio of 1:1 and infused into a rabbit whose reticuloendothelial system was blocked. Blood samples were collected for up to 24 hours after transfusion and the numbers of CD36⁺ and CD36^- PLTs were measured by flow cytometer (FCM) to determine PLT recovery rates. Each experiment consisted of one CD36^- and two CD36⁺ PLT components, and was repeated three times.

Results/Findings:

CD42b expression slightly decreased and both P-selectin expression and Annexin V binding gradually increased during storage of CD36⁺ and CD36^- PLTs, to similar extents in both PLT types. However, one of the six CD36⁺ components showed very high Annexin V binding on day 7. Changes in PLT count, pH, glucose and lactate concentrations, and collagen- and ADP-induced aggregation during storage were not significantly different between the CD36⁺ and CD36^- PLTs, except for the pH on day 1.
FCM accurately identified CD36^- PLTs among CD36⁺-predominant PLTs. Despite significant differences between individual rabbits, the recovery rate of CD36^- PLTs was significantly greater than that of CD36⁺ PLTs both immediately (0 minutes) after PLT infusion on day 3 of storage [Figure A(a)] and from 0 to 150 minutes after PLT infusion on day 7 [Figure A(b)].
Thus, in vitro assay results showed no remarkable difference between CD36^- and CD36⁺ PLTs up to day 7, and the animal study results showed similar recovery rates up to day 3. The higher mean recovery rate of CD36^- PLTs on day 7 is probably due to the influence of the CD36⁺ PLT component, which showed high Annexin V binding on day 7. In addition, the animal study suggests that PLT recovery rates are influenced more by individual variations in PLT functions and rabbit characteristics than by CD36 expression levels. While further studies are needed, the functions of CD36⁺ and CD36^- PLTs seem equivalent.

Conclusions: Our results suggest that this CD36-based method may be useful as a radioisotope-free approach for assessing the recovery and survival of transfused PLTs in vivo.