Improvement of platelet preservation by inhibition of TRPC6

BACKGROUND

The preservation of platelets (PLTs) by room temperature (RT) oscillation limits their shelf life to between 4 and 7 days because of the decrease in PLT function. TRPC6 is a non-selective mechanically sensitive cation channel that has been shown to mediate Ca²⁺ signalling, implying a role in PLT activation during preservation by RT oscillation.

OBJECTIVES

This study was designed to investigate whether inhibition of TRPC6 can improve the RT preservation of PLTs and the possible underlying mechanism.

METHODS

Human PLTs from whole blood were stored at 22 ± 2°C with oscillation in plasma or M-sol (mixture of solutions). BI-749327, a specific TRPC6 inhibitor, was administered throughout the preservation period. PLT distribution width (PDW), mean platelet volume (MPV), maximum platelet aggregation rate (MAR) and average aggregation rate (AAR) were measured. The MTT method was used to assess the relative viability of PLTs. Flow cytometry was used to measure the changes of Ca²⁺ concentration in PLTs and phosphatidylserine (PS) exposure on the PLT surface, and western blotting was used to assess the expression changes of platelet TRPC6 and CD62P proteins.

RESULTS

Compared with the control group, inhibition of TRPC6 with BI-749327 significantly reduced the PDW, MPV and Ca²⁺ concentration, the MAR and AAR were significantly increased, the expression of TRPC6 and CD62P protein was significantly down-regulated in PLTs, and the PS exposure was significantly reduced on the PLT surface. However, these effects were all reversed by activation of TRPC6.

CONCLUSION

Inhibition of TRPC6 improves the quality of PLT preservation by inhibiting the Ca²⁺ signal mediated by TRPC6.

Preventing adverse reactions in pediatric transfusions using washed platelet concentrate

Blood transfusion is an important form of supportive care in children; however, transfusion-associated adverse reactions (TARs) are a problem. As with adults, allergic transfusion reactions (ATRs) and febrile non-hemolytic transfusion reactions (FNHTRs) are major TARs, and the frequency of ATRs caused by platelet concentrate (PC) tends to be particularly high. The plasma component of the blood product is thought to be a major factor in the onset of TARs such as ATR and FNHTR. By contrast, in children, age, underlying disease, and number of blood transfusions may be relevant patient-related factors. Although acetaminophen or diphenhydramine may be used prophylactically to prevent TARs, there is no clear evidence of their effectiveness. Volume-reduced PC is used to prevent TARs; however, it may be difficult to maintain the quality of platelets. Plasma-replaced PC stored with platelet additive solution raises the concern that TARs cannot be completely prevented by residual plasma. Washed PC removes most of the plasma, so it can effectively prevent ATR and FNHTR. The recent development of platelet additive solution [M-sol, bicarbonate Ringer's solution supplemented with acid-citrate-dextrose formula A (BRS-A)] in Japan has enabled the maintenance of the quality of platelets for long periods. The clinical use of washed PC in Japan has therefore progressed. Washed PC with M-sol or BRS-A for pediatric patients can effectively prevent TARs without diminishing the transfusion effect. The supply of washed PC has begun from the Japanese Red Cross Society, and it has become possible to use washed PC at all medical institutions in Japan.

Transfusion outcome for volume- and plasma-reduced platelet concentrates for pediatric patients

BACKGROUND AND OBJECTIVES

Plasma reduction in platelet concentrate (PC) products has been reported to prevent large volume load and transfusion-related adverse reactions (TRARs). However, volume reduction might be associated with a poor transfusion response because of a deterioration in platelet (PLT) quality. Because PLT quality control and transfusion responses for recently washed PCs using PLT additive solutions are superior, we investigated the clinical safety and transfusion efficacy of volume-reduced washed PCs in pediatric patients.

MATERIALS AND METHODS

We prepared a simplified resuspended PC product (RPC) as a washed PC. Regular RPC (R-RPC) included equivalent volumes of bicarbonate Ringer's solution and anticoagulant citrate dextrose solution A (BRS-A) as the resuspension solution. Half RPC (H-RPC) was prepared by adding a half volume of BRS-A. Twenty-four pediatric patients were scheduled for transfusions with R-RPC and H-RPC up to 4 times. R-RPC was transfused 42 times into 24 patients. H-RPC was transfused 41 times into 23 patients.

RESULTS

Neither product was observed to cause TRARs. Although the calculated PLT recovery for H-RPC was significantly reduced, the posttransfusion corrected count increment (24 h) did not differ. Moreover, similar results were observed for vital signs during transfusion.

CONCLUSION

Volume-reduced washed PC can be transfused without causing TRARs, differences in vital signs, or inferior transfusion responses. Volume-reduced washed PC also provides the advantages of shortened transfusion times and reduced volume loads. Although a standard technique for stable resuspension is necessary, volume-reduced washed PC may be a beneficial option for children, including neonates, or individuals with cardiovascular or renal problems.