Vol.28 No.3（2006 June）：481-485

Effect of Freezing Rates on the Freeze-drying of Human Platelets
Xin-Li Zhou, Hong Zhu¹, Shao-Zhi Zhang, Fa-Ming Zhu¹, Guang-Ming Chen^*, Li-Xing Yan¹
( Cryobiology Laboratory, Institute of Refrigeration and Cryogenic Engineering, Zhejiang University, Hangzhou 310027, China; ¹Blood Center of Zhejiang Province, Hangzhou 310006, China )

Abstract Freeze-drying is an ideal alternative for long-term preservation of platelets in blood banks. Freezing process is important for recovery of freeze-dried of platelets. In this study, the effect of freezing rates on the recovery of freeze-dried human platelets in the presence of 1% bovine serum albumin and 20% trehalose were investigated. Three cooling methods were employed, including gradient cooling, shelf cooling and plunging the sample into liquid nitrogen. The results show that shelf cooling was the best way to cool the sample, the highest recovery of freeze-dried and rehydrated platelets reached (93.0±5.2)%, the optimum rate of freezing is about 10 °C/min. Furthermore, SEM was employed to investigate the morphology of freeze-dried and rehydrated platelets but more rounder compared with fresh platelets. The maximum aggregation rate of these platelets to thrombin (1 U/ml) was close to that of fresh platelets, but aggregation speed was more slowly than the fresh ones.

Key words platelets; freeze-drying; freezing rate

Received: October 28, 2005 Accepted: February 6, 2006

This work was supported by the National Natural Science Foundation of China (No.50076039) and the Science Foundation of Ministry of Health (No.WKJ2005-2-037)

^*Corresponding author. Tel: 86-571-87951680, Fax: 86-571-87952464, E-mail: gmchen@zju.edu.cn