Freeze-drying of mononuclear cells derived from umbilical cord blood followed by colony formation.
BACKGROUND
We recently showed that freeze-dried cells stored for 3 years at room temperature can direct embryonic development following cloning. However, viability, as evaluated by membrane integrity of the cells after freeze-drying, was very low; and it was mainly the DNA integrity that was preserved. In the present study, we improved the cells' viability and functionality after freeze-drying.


RESULTS
We optimized the conditions of directional freezing, i.e. interface velocity and cell concentration, and we added the antioxidant EGCG to the freezing solution. The study was performed on mononuclear cells (MNCs) derived from human umbilical cord blood. After freeze-drying, we tested the viability, number of CD34(+)-presenting cells and ability of the rehydrated hematopoietic stem cells to differentiate into different blood cells in culture. The viability of the MNCs after freeze-drying and rehydration with pure water was 88%-91%. The total number of CD34(+)-presenting cells and the number of colonies did not change significantly when evaluated before freezing, after freeze-thawing, and after freeze-drying (5.4 x 10(4)+/-4.7, 3.49 x 10(4)+/-6 and 6.31 x 10(4)+/-12.27 cells, respectively, and 31+/-25.15, 47+/-45.8 and 23.44+/-13.3 colonies, respectively).


CONCLUSIONS
This is the first report of nucleated cells which have been dried and then rehydrated with double-distilled water remaining viable, and of hematopoietic stem cells retaining their ability to differentiate into different blood cells.
Natan
Dity
D
Core Dynamics Ltd, Ness-Ziona, Israel. dity@coredynamics.com
Nagler
Arnon
A
Arav
Amir
A
D002392:Catechin / Q000008:administration & dosage / Q000031:analogs & derivatives; D002470:Cell Survival; D003470:Culture Media; D004305:Dose-Response Relationship, Drug; D005312:Fetal Blood / Q000166:cytology*; D005612:Freeze Drying; D006801:Humans; D008855:Microscopy, Electron, Scanning; D009000:Monocytes / Q000166:cytology*
D003470:Culture Media; D002392:Catechin; C045651:epigallocatechin gallate