Publications (2)5.5 Total impact
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Article: Bone marrow CD34+ cells expanded on human brain endothelial cells reconstitute lethally irradiated baboons in a variable manner.
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ABSTRACT: Increased cell dose has a positive impact on the therapeutic outcome of bone marrow (BM) hematopoietic stem cell (HSC) transplant. However, methods to successfully expand BM HSCs have yet to be achieved. It has been shown previously that ex vivo expansion of BM cells using porcine microvascular endothelial cells can rescue a baboon from a lethal dose of radiation. However, in a prior study, baboons that received CD34+ cell doses less than 4 x 10(6) cells/kg body weight failed to achieve hematopoietic reconstitution. In our present study we used human brain endothelial cells (HUBECs) and cytokines to expand BM cells, and examined their ability to provide hematopoietic reconstitution in three lethally irradiated baboons following autologous transplant as a surrogate preclinical model. After ex vivo culture, the grafts represented a 1.8- to 2.1-fold expansion of CD34+ cells, a 3.7- to 13.2-fold increase of colony-forming cells, and a 1.9- to 3.2-fold increase of cobblestone area-forming cells, in comparison to the input cell numbers. Despite transplanting CD34+ cell grafts displaying a comparable degree of expansion, there was an obvious variability in the kinetics of hematopoietic reconstitution. The variation in hematopoietic reconstitution cannot be fully explained by the properties tested in expanded CD34+ cells, and warrant caution against taking into account such attributes as cell dose, expression of adhesion molecules, and migration as a measure of successful expansion of HSCs.Leukemia & lymphoma 06/2010; 51(6):1121-7. · 2.40 Impact Factor -
Article: Cord blood stem cell expansion is permissive to epigenetic regulation and environmental cues.
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ABSTRACT: Augmentation of the number of cord blood (CB) hematopoietic stem cells (HSC) present in a unit is required before it can be considered as an alternative graft for hematopoietic reconstitution for adult patients. In order to further optimize strategies to augment HSC numbers, we examined whether expansion of HSC mediated by epigenetic mechanisms remains permissive to external environmental cues. The chromatin-modifying agents 5-aza-2'-deoxycytidine (5azaD) and trichostatin A (TSA) were used to ameliorate epigenetic alteration of CB cells during ex vivo culture by adding various cytokines. After culture, CD34(+)CD90(+) cell numbers, their division history, in vitro clonogenic potential, and in vivo hematopoietic reconstitution potential and frequency were determined. 5azaD/TSA-treated, CD34(+)CD90(+) cells were greatly influenced in terms of their degree of expansion, clonogenic potential, cell-division rate, and transplantability by the combination of cytokines used in culture. Furthermore, our current results verify that the sequential addition of 5azaD followed by TSA is crucial for expansion of HSC. We demonstrate that following 5azaD/TSA treatment, the rate of CD34(+)CD90(+) cell division is also dependent on the cytokine cocktail and that this is associated with functional changes, including alteration of in vitro clonogenic potential and in vivo reconstitution potential. Our studies indicate there are interactions between intrinsic factors influenced by epigenetic mechanisms and external environmental signals in the regulation of HSC expansion. Epigenetic influences on HSC can be accentuated by environmental factors. Regulation of the rate of divisions may be a critical determinant for the maintenance of HSC functional potency during ex vivo expansion.Experimental hematology 07/2009; 37(9):1084-95. · 3.11 Impact Factor
