Freeze-dried rehydrated human blood platelets regulate intracellular pH

Area of Science:

• Biotechnology
• Hematology
• Cell Biology

Background:

• Long-term dry storage of platelets (PLTs) could significantly enhance storage capabilities.
• Evaluating the intracellular pH (pHi) regulation of trehalose-loaded, freeze-dried, and rehydrated PLTs is crucial.

Purpose of the Study:

• To assess the pHi regulation capacity of freeze-dried and rehydrated human platelets preserved with trehalose.
• To determine if the pHi regulatory mechanisms remain functional after freeze-drying and rehydration.

Main Methods:

• Human PLTs were freeze-dried with trehalose and subsequently rehydrated.
• Intracellular pH (pHi) was measured using the BCECF-AM dye in resting, acidified (nigericin), and stimulated (thrombin) cells.
• The sodium-proton pump activity was assessed, including its inhibition by 5-(N-methyl-N-isobutyl)amiloride (MIA).

Main Results:

• Rehydrated PLTs exhibited a normal pHi (7.27) comparable to fresh control PLTs.
• Na+-dependent pHi recovery followed Michaelis-Menten kinetics in both rehydrated and control PLTs, with similar Vmax and exchange constants.
• The sodium-hydrogen exchanger 1 (NHE1) remained sensitive to MIA inhibition post-freeze-drying and rehydration.

Conclusions:

• The pHi regulation system in platelets is substantially preserved following freeze-drying and rehydration.
• Trehalose-mediated preservation effectively maintains the functional integrity of platelet pHi regulatory mechanisms.
• These findings support the potential for long-term dry storage of platelets.