Experimental study on rehydration conditions of freeze-dried platelets

A rehydration process for freeze-dried human platelets was studied on 1 ml of samples. The effects of prehydration duration, prehydration temperature, and rehydration solution on the recovery rate, mean platelet volume (MPV), and platelet distribution width (PDW) were investigated. The mass changes during the prehydration process were also studied. Three prehy-dration durations: 0, 1.5, and 3.5 h, and two rehydration solutions: platelet-poor plasma and phosphate-buffered saline (PBS), were tested. It was found that: (1) the prehydration was of significance; (2) 1.5 h of prehydration had better effects than 3.5 h of pre-hydration; (3) as a rehydration solution, the platelet-poor plasma behaved better than the PBS. The impacts of prehydration du-ration and temperature on the results were studied. There was almost no difference between 35 and 37 °C. Among all the prehy-dration durations tested, 15, 30, 60, 90, and 120 min, the best result was achieved with the time duration of 15 min. The weights of prehydrated platelets at the end of each test were measured and the water contents were calculated. After 15 min of prehydration, the water contents in the samples were about (4.8±0.01)% and (5.27±0.29)% (w/w) corresponding to the conditions of 35 and 37 °C, respectively. These results will be helpful for further studies on the freeze-drying of mammalian cells.

Rapid Communication:Preliminary study on the freeze-drying of human bone marrow-derived mesenchymal stem cells

Long-term preservation and easy transportation of human bone marrow-derived mesenchymal stem cells(hBM-MSCs) will facilitate their application in medical treatment and bioengineering.A pilot study on the freeze-drying of hBM-MSCs was carried out.hBM-MSCs were loaded with trehalose.The glass transition temperature of the freeze-drying suspension was measured to provide information for the cooling and primary drying experiment.After freeze-drying,various rehydration processes were tested.The highest recovery rate of hBM-MSCs was(69.33± 13.08) %.Possible methods to improve freeze-drying outcomes are discussed.In conclusion,the present study has laid a foundation for the freeze-drying hBM-MSCs.

Moisture sorption characteristics of freeze-dried human platelets

Freeze-drying is a promising method for a long-term storage of human platelets.The moisture sorption characteristics of freeze-dried human platelets(FDHPs) were studied in this paper.The moisture sorption isotherms of FDHPs and freeze-dried lyophilization buffer(FDLB) were measured at 4,25,and 37°C.The experimental data were fitted to Brunauer-Emmett-Teller(BET) and Guggenheim-Anderson-de Boer(GAB) equations.There were no sig-nificant statistical differences(P>0.05) between the sorption characteristics of FDHPs and FDLB at 4 and 25°C,while FDHPs absorbed more water at 37°C.The net isosteric heat of sorption was derived.The heat for FDHPs showed an abnormal negative value at low moisture contents when 25 and 37°C data were used.Dynamic sorption experiments were carried out at 25°C with environmental water activity controlled at 0.75,0.85,and 0.90.The moisture diffusion coefficient was fitted to be 8.24×10 -12 m 2 /s when experimental data at initial time were used.These results would be helpful in choosing prehydration and storage condition for FDHPs.