Porcine hematopoiesis on primate stroma in long-term cultures: enhanced growth with neutralizing tumor necrosis factor-alpha and tumor growth factor-beta antibodies.
BACKGROUND
Donor hematopoiesis is at a competitive disadvantage when bone marrow transplantation is across species barriers. This could present major limitations to xenogeneic stem cell transplantation as an approach to tolerance induction. An in vitro model of xenogeneic engraftment was established to identify inhibitors of porcine hematopoiesis in a primate environment.


METHODS
Porcine bone marrow cells (BMC), in the presence or absence of primate CD34+ positive cells, were cultured for 4-6 weeks on primate stroma with porcine cytokines. Cellularity and growth of colony-forming cells were indicators of hematopoietic growth. Effects of soluble factors were determined by using Transwell inserts to separate porcine cells from stroma. Neutralizing antibodies for human transforming growth factor-beta (TGF-beta) and tumor necrosis factor-alpha (TNF-alpha) were added to cultures.


RESULTS
Porcine hematopoiesis can be maintained in long-term cultures on primate stroma with pig cytokines. Adding BMC to the stroma below Transwell-containing porcine cells dramatically inhibited porcine hematopoiesis, showing an inhibitory role for soluble factors. Neutralizing antibodies against TNF-alpha or TGF-beta caused a modest enhancement of porcine hematopoiesis; however, the combination of both led to a substantial increase. Inhibitory effects of these cytokines were confirmed by adding TNF-alpha and TGF-beta to porcine cultures.


CONCLUSIONS
Porcine cells may be more sensitive to inhibitory effects of TNF-alpha and TGF-beta than primate cells and are at a disadvantage when in a primate environment. Potential implications of this observation are discussed in the context of establishing specific immune tolerance via mixed chimerism to facilitate xenotransplantation.
Giovino
Maria A
MA
BioTransplant, Incorporated, Charlestown, MA 02129, USA.
Down
Julian D
JD
Jackson
John D
JD
Sykes
Megan
M
Monroy
Rodney L
RL
White-Scharf
Mary E
ME
D000818:Animals; D000906:Antibodies / Q000276:immunology; D001854:Bone Marrow Cells / Q000502:physiology; D002478:Cells, Cultured; D018920:Coculture Techniques; D006410:Hematopoiesis; D007377:Interleukin-3 / Q000494:pharmacology; D008233:Lymphotoxin-alpha / Q000037:antagonists & inhibitors* / Q000276:immunology; D008252:Macaca fascicularis; D019089:Stem Cell Factor / Q000494:pharmacology; D017154:Stromal Cells / Q000502:physiology; D013552:Swine; D014183:Transplantation, Heterologous / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000276:immunology
D000906:Antibodies; D007377:Interleukin-3; D008233:Lymphotoxin-alpha; D019089:Stem Cell Factor; D014409:Tumor Necrosis Factor-alpha