Cryopreservation and mycophenolate therapy are detrimental to hematopoietic progenitor cells.
BACKGROUND
The aim of the present study was to determine whether certain components of nonmyeloablative regimens for hematopoietic cell transplantation might compromise the growth of hematopoietic progenitors.


METHODS
Porcine peripheral blood progenitor cells (PBPC) were cytokine-mobilized, collected by leukapheresis, and cryopreserved using 5% dimethyl sulfoxide and 6% hydroxyethyl starch. The influence of cryopreservation on PBPC was tested in vitro by enumeration of colony-forming units (CFUs) in methylcellulose and cobblestone area-forming cell (CAFC) subsets in stromal-associated long-term cultures on fresh and frozen PBPC. The effects of mycophenolate mofetil (MMF) on porcine PBPC and baboon and human bone marrow (BM) were tested in vitro by adding varying doses of MMF to the CFU assays. One baboon was treated with increasing doses of MMF (100-500 mg/kg per day continuously intravenous), and sequential BM aspirations were tested for CFU content.


RESULTS
Fresh cytokine-mobilized PBPC had similar frequencies of progenitor cells when compared with porcine BM. Freezing-thawing of PBPC had no effect on porcine CFUs but reduced the recovery of CAFCs by more than 90%. In vitro, MMF completely inhibited the development of porcine and human CFUs at a concentration of 1 microg/mL and of baboon CFUs at levels between 10 and 100 microg/mL. Plasma-free mycophenolic acid levels of 10 to 30 microg/mL were associated with decreased CFUs in the BM.


CONCLUSIONS
Cryopreservation and MMF potentially prevent engraftment of porcine PBPC by reducing the content or development of progenitor cells. These results indicate that the use of fresh PBPC might improve the induction of mixed hematopoietic chimerism and raise the possibility that use of high doses of MMF in the poststem cell transplant may compromise engraftment.
Bühler
Leo
L
Transplantation Biology Research Center, Massachusetts General Hospital/Harvard Medical School, Boston, MA, USA.
Kurilla-Mahon
Barbara
B
Chang
Qing
Q
Abraham
Sonny
S
Alwayn
Ian P J
IP
Appel
James Z
JZ
Newman
Dawne
D
Awwad
Michel
M
White-Scharf
Mary E
ME
Sackstein
Roberto
R
Sachs
David H
DH
Cooper
David K C
DK
Down
Julian D
JD
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D015925:Cryopreservation; D005260:Female; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D007166:Immunosuppressive Agents / Q000097:blood / Q000494:pharmacology*; D066298:In Vitro Techniques; D007937:Leukapheresis; D008297:Male; D009173:Mycophenolic Acid / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology*; D010215:Papio; D013556:Swine, Miniature; D014183:Transplantation, Heterologous
D007166:Immunosuppressive Agents; D009173:Mycophenolic Acid