Cryopreservation of Hematopoietic and Non-Hematopoietic Stem Cells – A Review for the Clinician

Abstract

The transplantation of stem cells can be performed in an autologous, where the recipient donates his own stem cells for later use, or in an allogeneic fashion, where the donor and the recipient are two different persons (Berz, McCormack, Winer, Colvin, & Peter J Quesenberry, 2007; A. Gratwohl et al., 2010). In some clinical settings, stem cells can be utilized within a 72 hour timeframe without the need for extensive storage (Fleming & A Hubel, 2006; Allison Hubel, Carlquist, Clay, & Jeff McCullough, 2004; Pettengell, Woll, O'Connor, Dexter, & Testa, 1994). The autologous transplantation of cellular products and the therapeutic use of umbilical cord stem cells rely heavily on the preservation of stem cells after initial collection to be utilized at a later point in time (Berz, McCormack, Winer, Colvin, & Peter J Quesenberry, 2007). Hematopoietic stem cell transplantation has been in clinical use for decades to treat benign and malignant hematologic and non-hematologic conditions (C. J. Hunt, 2011). The principal sources for those therapeutic strategies are bone marrow, peripheral blood hematopoietic progenitor cells and stem cells derived from umbilical cord blood. Although clinicians have decades of experience with the use of hematopoietic stem cells(HSC), the interest in the clinical use of non-hematopoietic stem cells, such as embryonic(C. J. Hunt, 2011; Leeb et al., 2011), mesenchymal (Ding, Shyu, & Lin, 2011; Leclerc et al., 2011; Puglisi et al., 2011) and induced pluripotent stem cells (Leeb et al., 2011; Sohni & Verfaillie, 2011) is rapidly expanding. The therapeutic strategies utilizing such cellular products, depend heavily on the effective preservation of those cell products for clinical use at a later point in time. The need for ready availability of such products calls for storage procedures with favorable graft survival rates and a tolerable toxicity profile. While cryopreservation protocols for HSC are well developed, the field for non-hematopoietic stem cells still remains to be defined. The cryopreservation of all stem cells follows certain principal steps; First, Cytoreduction and prefreezing processing of the freshly collected graft. Second, the cryopreservative medium is prepared and added. Third, the graft is assessed for viability and integrity. Microbial contamination is ruled out. Fourth, freezing of the stem cells is performed. Fifth, thawing of the cryopreserved graft is conducted. Last, the post thawing processing is