Jeffrey J. Ross, Zhigang Hong, Ben Willenbring, Lepeng Zeng, Brett Isenberg, Eu Han Lee, Morayma Reyes, Susan A. Keirstead, E. Kenneth Weir, Robert T. Tranquillo, Catherine M. Verfaillie
Endothelial progenitor cells (EPCs) are essential in vasculogenesis and wound healing, but their circulating and wound level numbers are decreased in diabetes. This study aimed to determine mechanisms responsible for the diabetic defect in circulating and wound EPCs. Since mobilization of BM EPCs occurs via eNOS activation, we hypothesized that eNOS activation is impaired in diabetes, which results in reduced EPC mobilization. Since hyperoxia activates NOS in other tissues, we investigated whether hyperoxia restores EPC mobilization in diabetic mice through BM NOS activation. Additionally, we studied the hypothesis that impaired EPC homing in diabetes is due to decreased wound level stromal cell–derived factor–1α (SDF-1α), a chemokine that mediates EPC recruitment in ischemia. Diabetic mice showed impaired phosphorylation of BM eNOS, decreased circulating EPCs, and diminished SDF-1α expression in cutaneous wounds. Hyperoxia increased BM NO and circulating EPCs, effects inhibited by the NOS inhibitor N-nitro-l-arginine-methyl ester. Administration of SDF-1α into wounds reversed the EPC homing impairment and, with hyperoxia, synergistically enhanced EPC mobilization, homing, and wound healing. Thus, hyperoxia reversed the diabetic defect in EPC mobilization, and SDF-1α reversed the diabetic defect in EPC homing. The targets identified, which we believe to be novel, can significantly advance the field of diabetic wound healing.
Katherine A. Gallagher, Zhao-Jun Liu, Min Xiao, Haiying Chen, Lee J. Goldstein, Donald G. Buerk, April Nedeau, Stephen R. Thom, Omaida C. Velazquez
Smooth muscle formation and function are critical in development and postnatal life. Hence, studies aimed at better understanding SMC differentiation are of great importance. Here, we report that multipotent adult progenitor cells (MAPCs) isolated from rat, murine, porcine, and human bone marrow demonstrate the potential to differentiate into cells with an SMC-like phenotype and function. TGF-β1 alone or combined with PDGF-BB in serum-free medium induces a temporally correct expression of transcripts and proteins consistent with smooth muscle development. Furthermore, SMCs derived from MAPCs (MAPC-SMCs) demonstrated functional L-type calcium channels. MAPC-SMCs entrapped in fibrin vascular molds became circumferentially aligned and generated force in response to KCl, the L-type channel opener FPL64176, or the SMC agonists 5-HT and ET-1, and exhibited complete relaxation in response to the Rho-kinase inhibitor Y-27632. Cyclic distention (5% circumferential strain) for 3 weeks increased responses by 2- to 3-fold, consistent with what occurred in neonatal SMCs. These results provide evidence that MAPC-SMCs are phenotypically and functionally similar to neonatal SMCs and that the in vitro MAPC-SMC differentiation system may be an ideal model for the study of SMC development. Moreover, MAPC-SMCs may lend themselves to tissue engineering applications.
Jeffrey J. Ross, Zhigang Hong, Ben Willenbring, Lepeng Zeng, Brett Isenberg, Eu Han Lee, Morayma Reyes, Susan A. Keirstead, E. Kenneth Weir, Robert T. Tranquillo, Catherine M. Verfaillie
Vision loss associated with ischemic diseases such as retinopathy of prematurity and diabetic retinopathy are often due to retinal neovascularization. While significant progress has been made in the development of compounds useful for the treatment of abnormal vascular permeability and proliferation, such therapies do not address the underlying hypoxia that stimulates the observed vascular growth. Using a model of oxygen-induced retinopathy, we demonstrate that a population of adult BM–derived myeloid progenitor cells migrated to avascular regions of the retina, differentiated into microglia, and facilitated normalization of the vasculature. Myeloid-specific hypoxia-inducible factor 1α (HIF-1α) expression was required for this function, and we also demonstrate that endogenous microglia participated in retinal vascularization. These findings suggest what we believe to be a novel therapeutic approach for the treatment of ischemic retinopathies that promotes vascular repair rather than destruction.
Matthew R. Ritter, Eyal Banin, Stacey K. Moreno, Edith Aguilar, Michael I. Dorrell, Martin Friedlander
Tissue regeneration requires the recruitment of adult stem cells and their differentiation into mature committed cells. In this study we describe what we believe to be a novel approach for tendon regeneration based on a specific signalling molecule, Smad8, which mediates the differentiation of mesenchymal stem cells (MSCs) into tendon-like cells. A biologically active Smad8 variant was transfected into an MSC line that coexpressed the osteogenic gene bone morphogenetic protein 2 (BMP2). The engineered cells demonstrated the morphological characteristics and gene expression profile of tendon cells both in vitro and in vivo. In addition, following implantation in an Achilles tendon partial defect, the engineered cells were capable of inducing tendon regeneration demonstrated by double quantum filtered MRI. The results indicate what we believe to be a novel mechanism in which Smad8 inhibits the osteogenic pathway in MSCs known to be induced by BMP2 while promoting tendon differentiation. These findings may have considerable importance for the therapeutic replacement of tendons or ligaments and for engineering other tissues in which BMP plays a pivotal developmental role.
Andrea Hoffmann, Gadi Pelled, Gadi Turgeman, Peter Eberle, Yoram Zilberman, Hadassah Shinar, Keren Keinan-Adamsky, Andreas Winkel, Sandra Shahab, Gil Navon, Gerhard Gross, Dan Gazit
CD34+ bone marrow–derived progenitor cells contribute to tissue repair by differentiating into endothelial cells, vascular smooth muscle cells, hematopoietic cells, and possibly other cell types. However, the mechanisms by which circulating progenitor cells home to remodeling tissues remain unclear. Here we show that integrin α4β1 (VLA-4) promotes the homing of circulating progenitor cells to the α4β1 ligands VCAM and cellular fibronectin, which are expressed on actively remodeling neovasculature. Progenitor cells, which express integrin α4β1, homed to sites of active tumor neovascularization but not to normal nonimmune tissues. Antagonists of integrin α4β1, but not other integrins, blocked the adhesion of these cells to endothelia in vitro and in vivo as well as their homing to neovasculature and outgrowth into differentiated cell types. These studies describe an adhesion event that facilitates the homing of progenitor cells to the neovasculature.
Hui Jin, Aparna Aiyer, Jingmei Su, Per Borgstrom, Dwayne Stupack, Martin Friedlander, Judy Varner
Ischemia causes kidney tubular cell damage and abnormal renal function. The kidney is capable of morphological restoration of tubules and recovery of function. Recently, it has been suggested that cells repopulating the ischemically injured tubule derive from bone marrow stem cells. We studied kidney repair in chimeric mice expressing GFP or bacterial β-gal or harboring the male Y chromosome exclusively in bone marrow-derived cells. In GFP chimeras, some interstitial cells but not tubular cells expressed GFP after ischemic injury. More than 99% of those GFP interstitial cells were leukocytes. In female mice with male bone marrow, occasional tubular cells (0.06%) appeared to be positive for the Y chromosome, but deconvolution microscopy revealed these to be artifactual. In β-gal chimeras, some tubular cells also appeared to express β-gal as assessed by X-gal staining, but following suppression of endogenous (mammalian) β-gal, no tubular cells could be found that stained with X-gal after ischemic injury. Whereas there was an absence of bone marrow–derived tubular cells, many tubular cells expressed proliferating cell nuclear antigen, which is reflective of a high proliferative rate of endogenous surviving tubular cells. Upon i.v. injection of bone marrow mesenchymal stromal cells, postischemic functional renal impairment was reduced, but there was no evidence of differentiation of these cells into tubular cells of the kidney. Thus, our data indicate that bone marrow–derived cells do not make a significant contribution to the restoration of epithelial integrity after an ischemic insult. It is likely that intrinsic tubular cell proliferation accounts for functionally significant replenishment of the tubular epithelium after ischemia.
Jeremy S. Duffield, Kwon Moo Park, Li-Li Hsiao, Vicki R. Kelley, David T. Scadden, Takaharu Ichimura, Joseph V. Bonventre
Ischemic injury to the kidney produces acute tubular necrosis and apoptosis followed by tubular regeneration and recovery of renal function. Although mitotic cells are present in the tubules of postischemic kidneys, the origins of the proliferating cells are not known. Bone marrow cells (BMCs) can differentiate across lineages to repair injured organs, including the kidney. However, the relative contribution of intrarenal cells and extrarenal cells to kidney regeneration is not clear. We produced transgenic mice that expressed enhanced GFP (EGFP) specifically and permanently in mature renal tubular epithelial cells. Following ischemia/reperfusion injury (IRI), EGFP-positive cells showed incorporation of BrdU and expression of vimentin, which provides direct evidence that the cells composing regenerating tubules are derived from renal tubular epithelial cells. In BMC-transplanted mice, 89% of proliferating epithelial cells originated from host cells, and 11% originated from donor BMCs. Twenty-eight days after IRI, the kidneys contained 8% donor-derived cells, of which 8.4% were epithelial cells, 10.6% were glomerular cells, and 81% were interstitial cells. No renal functional improvement was observed in mice that were transplanted with exogenous BMCs. These results show that intrarenal cells are the main source of renal repair, and a single injection of BMCs does not make a significant contribution to renal functional or structural recovery.
Fangming Lin, Ashley Moran, Peter Igarashi
Parkinson disease (PD) is a neurodegenerative disorder characterized by loss of midbrain dopaminergic (DA) neurons. ES cells are currently the most promising donor cell source for cell-replacement therapy in PD. We previously described a strong neuralizing activity present on the surface of stromal cells, named stromal cell–derived inducing activity (SDIA). In this study, we generated neurospheres composed of neural progenitors from monkey ES cells, which are capable of producing large numbers of DA neurons. We demonstrated that FGF20, preferentially expressed in the substantia nigra, acts synergistically with FGF2 to increase the number of DA neurons in ES cell–derived neurospheres. We also analyzed the effect of transplantation of DA neurons generated from monkey ES cells into 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine–treated (MPTP-treated) monkeys, a primate model for PD. Behavioral studies and functional imaging revealed that the transplanted cells functioned as DA neurons and attenuated MPTP-induced neurological symptoms.
Yasushi Takagi, Jun Takahashi, Hidemoto Saiki, Asuka Morizane, Takuya Hayashi, Yo Kishi, Hitoshi Fukuda, Yo Okamoto, Masaomi Koyanagi, Makoto Ideguchi, Hideki Hayashi, Takayuki Imazato, Hiroshi Kawasaki, Hirofumi Suemori, Shigeki Omachi, Hidehiko Iida, Nobuyuki Itoh, Norio Nakatsuji, Yoshiki Sasai, Nobuo Hashimoto
The chemokine stromal cell–derived factor–1 (SDF-1) and its receptor, CXCR4, play a major role in migration, retention, and development of hematopoietic progenitors in the bone marrow. We report the direct involvement of atypical PKC-ζ in SDF-1 signaling in immature human CD34+-enriched cells and in leukemic pre-B acute lymphocytic leukemia (ALL) G2 cells. Chemotaxis, cell polarization, and adhesion of CD34+ cells to bone marrow stromal cells were found to be PKC-ζ dependent. Overexpression of PKC-ζ in G2 and U937 cells led to increased directional motility to SDF-1. Interestingly, impaired SDF-1–induced migration of the pre-B ALL cell line B1 correlated with reduced PKC-ζ expression. SDF-1 triggered PKC-ζ phosphorylation, translocation to the plasma membrane, and kinase activity. Furthermore we identified PI3K as an activator of PKC-ζ, and Pyk-2 and ERK1/2 as downstream targets of PKC-ζ. SDF-1–induced proliferation and MMP-9 secretion also required PKC-ζ activation. Finally, we showed that in vivo engraftment, but not homing, of human CD34+-enriched cells to the bone marrow of NOD/SCID mice was PKC-ζ dependent and that injection of mice with inhibitory PKC-ζ pseudosubstrate peptides resulted in mobilization of murine progenitors. Our results demonstrate a central role for PKC-ζ in SDF-1–dependent regulation of hematopoietic stem and progenitor cell motility and development.
Isabelle Petit, Polina Goichberg, Asaf Spiegel, Amnon Peled, Chaya Brodie, Rony Seger, Arnon Nagler, Ronen Alon, Tsvee Lapidot
Diabetic retinopathy is the leading cause of blindness in working-age adults. It is caused by oxygen starvation in the retina inducing aberrant formation of blood vessels that destroy retinal architecture. In humans, vitreal stromal cell–derived factor–1 (SDF-1) concentration increases as proliferative diabetic retinopathy progresses. Treatment of patients with triamcinolone decreases SDF-1 levels in the vitreous, with marked disease improvement. SDF-1 induces human retinal endothelial cells to increase expression of VCAM-1, a receptor for very late antigen–4 found on many hematopoietic progenitors, and reduce tight cellular junctions by reducing occludin expression. Both changes would serve to recruit hematopoietic and endothelial progenitor cells along an SDF-1 gradient. We have shown, using a murine model of proliferative adult retinopathy, that the majority of new vessels formed in response to oxygen starvation originate from hematopoietic stem cell–derived endothelial progenitor cells. We now show that the levels of SDF-1 found in patients with proliferative retinopathy induce retinopathy in our murine model. Intravitreal injection of blocking antibodies to SDF-1 prevented retinal neovascularization in our murine model, even in the presence of exogenous VEGF. Together, these data demonstrate that SDF-1 plays a major role in proliferative retinopathy and may be an ideal target for the prevention of proliferative retinopathy.
Jason M. Butler, Steven M. Guthrie, Mehmet Koc, Aqeela Afzal, Sergio Caballero, H. Logan Brooks, Robert N. Mames, Mark S. Segal, Maria B. Grant, Edward W. Scott
Pluripotent bone marrow–derived side population (BM-SP) stem cells have been shown to repopulate the hematopoietic system and to contribute to skeletal and cardiac muscle regeneration after transplantation. We tested BM-SP cells for their ability to regenerate heart and skeletal muscle using a model of cardiomyopathy and muscular dystrophy that lacks δ-sarcoglycan. The absence of δ-sarcoglycan produces microinfarcts in heart and skeletal muscle that should recruit regenerative stem cells. Additionally, sarcoglycan expression after transplantation should mark successful stem cell maturation into cardiac and skeletal muscle lineages. BM-SP cells from normal male mice were transplanted into female δ-sarcoglycan–null mice. We detected engraftment of donor-derived stem cells into skeletal muscle, with the majority of donor-derived cells incorporated within myofibers. In the heart, donor-derived nuclei were detected inside cardiomyocytes. Skeletal muscle myofibers containing donor-derived nuclei generally failed to express sarcoglycan, with only 2 sarcoglycan-positive fibers detected in the quadriceps muscle from all 14 mice analyzed. Moreover, all cardiomyocytes with donor-derived nuclei were sarcoglycan-negative. The absence of sarcoglycan expression in cardiomyocytes and skeletal myofibers after transplantation indicates impaired differentiation and/or maturation of bone marrow–derived stem cells. The inability of BM-SP cells to express this protein severely limits their utility for cardiac and skeletal muscle regeneration.
Karen A. Lapidos, Yiyin E. Chen, Judy U. Earley, Ahlke Heydemann, Jill M. Huber, Marcia Chien, Averil Ma, Elizabeth M. McNally
Inherited retinal degenerations afflict 1 in 3,500 individuals and are a heterogeneous group of diseases that result in profound vision loss, usually the result of retinal neuronal apoptosis. Atrophic changes in the retinal vasculature are also observed in many of these degenerations. While it is thought that this atrophy is secondary to diminished metabolic demand in the face of retinal degeneration, the precise relationship between the retinal neuronal and vascular degeneration is not clear. In this study we demonstrate that whenever a fraction of mouse or human adult bone marrow–derived stem cells (lineage-negative hematopoietic stem cells [Lin– HSCs]) containing endothelial precursors stabilizes and rescues retinal blood vessels that would ordinarily completely degenerate, a dramatic neurotrophic rescue effect is also observed. Retinal nuclear layers are preserved in 2 mouse models of retinal degeneration, rd1 and rd10, and detectable, albeit severely abnormal, electroretinogram recordings are observed in rescued mice at times when they are never observed in control-treated or untreated eyes. The normal mouse retina consists predominantly of rods, but the rescued cells after treatment with Lin– HSCs are nearly all cones. Microarray analysis of rescued retinas demonstrates significant upregulation of many antiapoptotic genes, including small heat shock proteins and transcription factors. These results suggest a new paradigm for thinking about the relationship between vasculature and associated retinal neuronal tissue as well as a potential treatment for delaying the progression of vision loss associated with retinal degeneration regardless of the underlying genetic defect.
Atsushi Otani, Michael Ian Dorrell, Karen Kinder, Stacey K. Moreno, Steven Nusinowitz, Eyal Banin, John Heckenlively, Martin Friedlander
Duchenne muscular dystrophy (DMD) is a common X-linked disease characterized by widespread muscle damage that invariably leads to paralysis and death. There is currently no therapy for this disease. Here we report that a subpopulation of circulating cells expressing AC133, a well-characterized marker of hematopoietic stem cells, also expresses early myogenic markers. Freshly isolated, circulating AC133+ cells were induced to undergo myogenesis when cocultured with myogenic cells or exposed to Wnt-producing cells in vitro and when delivered in vivo through the arterial circulation or directly into the muscles of transgenic scid/mdx mice (which allow survival of human cells). Injected cells also localized under the basal lamina of host muscle fibers and expressed satellite cell markers such as M-cadherin and MYF5. Furthermore, functional tests of injected muscles revealed a substantial recovery of force after treatment. As these cells can be isolated from the blood, manipulated in vitro, and delivered through the circulation, they represent a possible tool for future cell therapy applications in DMD disease or other muscular dystrophies.
Yvan Torrente, Marzia Belicchi, Maurilio Sampaolesi, Federica Pisati, Mirella Meregalli, Giuseppe D’Antona, Rossana Tonlorenzi, Laura Porretti, Manuela Gavina, Kamel Mamchaoui, Maria Antonietta Pellegrino, Denis Furling, Vincent Mouly, Gillian S. Butler-Browne, Roberto Bottinelli, Giulio Cossu, Nereo Bresolin
Several recent reports have demonstrated that transplantation of bone marrow cells can result in the generation of functional hepatocytes. Cellular fusion between bone marrow–derived cells and host hepatocytes has been shown to be the mechanism of this phenomenon. However, the exact identity of the bone marrow cells that mediate cellular fusion has remained undetermined. Here we demonstrate that the hematopoietic progeny of a single hematopoietic stem cell (HSC) is sufficient to produce functional hepatic repopulation. Furthermore, transplantation of lymphocyte-deficient bone marrow cells and in vivo fate mapping of the myeloid lineage revealed that HSC-derived hepatocytes are primarily derived from mature myelomonocytic cells. In addition, using a Cre/lox–based strategy, we directly demonstrate that myeloid cells spontaneously fuse with host hepatocytes. Our findings raise the possibility that differentiated myeloid cells may be useful for future therapeutic applications of in vivo cellular fusion.
Fernando D. Camargo, Milton Finegold, Margaret A. Goodell
Given our recent discovery that it is possible to separate human epidermal stem cells of the skin from their more committed progeny (i.e., transit-amplifying cells and early differentiating cells) using FACS techniques, we sought to determine the comparative tissue regeneration ability of these keratinocyte progenitors. We demonstrate that the ability to regenerate a fully stratified epidermis with appropriate spatial and temporal expression of differentiation markers in a short-term in vitro organotypic culture system is an intrinsic characteristic of both epidermal stem and transit-amplifying cells, although the stem cell fraction is most capable of achieving homeostasis. Early differentiating keratinocytes exhibited limited short-term tissue regeneration under specific experimental conditions in this assay, although significant improvement was obtained by manipulating microenvironmental factors, that is, coculture with minimally passaged dermal cells or exogenous supply of the ECM protein laminin-10/11. Importantly, transplantation of all classes of keratinocyte progenitors into an in vivo setting demonstrated that tissue regeneration can be elicited from stem, transit-amplifying, and early differentiating keratinocytes for up to 10 weeks. These data illustrate that significant proliferative and tissue-regenerative capacity resides not only in keratinocyte stem cells as expected, but also in their more committed progeny, including early differentiating cells.
Amy Li, Normand Pouliot, Richard Redvers, Pritinder Kaur
The mitochondrial genome encodes 13 essential subunits of the respiratory chain and has remarkable genetics based on uniparental inheritance. Within human populations, the mitochondrial genome has a high rate of sequence divergence with multiple polymorphic variants and thus has played a major role in examining the evolutionary history of our species. In recent years it has also become apparent that pathogenic mitochondrial DNA (mtDNA) mutations play an important role in neurological and other diseases. Patients harbor many different mtDNA mutations, some of which are mtDNA mutations, some of which are inherited, but others that seem to be sporadic. It has also been suggested that mtDNA mutations play a role in aging and cancer, but the evidence for a causative role in these conditions is less clear. The accumulated data would suggest, however, that mtDNA mutations occur on a frequent basis. In this article we describe a new phenomenon: the accumulation of mtDNA mutations in human colonic crypt stem cells that result in a significant biochemical defect in their progeny. These studies have important consequences not only for understanding of the finding of mtDNA mutations in aging tissues and tumors, but also for determining the frequency of mtDNA mutations within a cell.
Robert W. Taylor, Martin J. Barron, Gillian M. Borthwick, Amy Gospel, Patrick F. Chinnery, David C. Samuels, Geoffrey A. Taylor, Stefan M. Plusa, Stephanie J. Needham, Laura C. Greaves, Thomas B.L. Kirkwood, Douglass M. Turnbull
Hematopoietic stem cells rarely contribute to hepatic regeneration, however, the mechanisms governing their homing to the liver, which is a crucial first step, are poorly understood. The chemokine stromal cell–derived factor-1 (SDF-1), which attracts human and murine progenitors, is expressed by liver bile duct epithelium. Neutralization of the SDF-1 receptor CXCR4 abolished homing and engraftment of the murine liver by human CD34+ hematopoietic progenitors, while local injection of human SDF-1 increased their homing. Engrafted human cells were localized in clusters surrounding the bile ducts, in close proximity to SDF-1–expressing epithelial cells, and differentiated into albumin-producing cells. Irradiation or inflammation increased SDF-1 levels and hepatic injury induced MMP-9 activity, leading to both increased CXCR4 expression and SDF-1–mediated recruitment of hematopoietic progenitors to the liver. Unexpectedly, HGF, which is increased following liver injury, promoted protrusion formation, CXCR4 upregulation, and SDF-1–mediated directional migration by human CD34+ progenitors, and synergized with stem cell factor. Thus, stress-induced signals, such as increased expression of SDF-1, MMP-9, and HGF, recruit human CD34+ progenitors with hematopoietic and/or hepatic-like potential to the liver of NOD/SCID mice. Our results suggest the potential of hematopoietic CD34+/CXCR4+cells to respond to stress signals from nonhematopoietic injured organs as an important mechanism for tissue targeting and repair.
Orit Kollet, Shoham Shivtiel, Yuan-Qing Chen, Jenny Suriawinata, Swan N. Thung, Mariana D. Dabeva, Joy Kahn, Asaf Spiegel, Ayelet Dar, Sarit Samira, Polina Goichberg, Alexander Kalinkovich, Fernando Arenzana-Seisdedos, Arnon Nagler, Izhar Hardan, Michel Revel, David A. Shafritz, Tsvee Lapidot
The paradigm for recovery of the renal tubule from acute tubular necrosis is that surviving cells from the areas bordering the injury must migrate into the regions of tubular denudation and proliferate to re-establish the normal tubular epithelium. However, therapies aimed at stimulating these events have failed to alter the course of acute renal failure in human trials. In the present study, we demonstrate that Lin–Sca-1+ cells from the adult mouse bone marrow are mobilized into the circulation by transient renal ischemia and home specifically to injured regions of the renal tubule. There they differentiate into renal tubular epithelial cells and appear to constitute the majority of the cells present in the previously necrotic tubules. Loss of stem cells following bone marrow ablation results in a greater rise in blood urea nitrogen after renal ischemia, while stem cell infusion after bone marrow ablation reverses this effect. Thus, therapies aimed at enhancing the mobilization, propagation, and/or delivery of bone marrow stem cells to the kidney hold potential as entirely new approaches for the treatment of acute tubular necrosis.
Sujata Kale, Anil Karihaloo, Paul R. Clark, Michael Kashgarian, Diane S. Krause, Lloyd G. Cantley
The only curative therapy for sickle cell disease (SCD) is allogeneic hematopoietic stem cell (HSC) transplantation. Gene therapy approaches for autologous HSC transplantation are being developed. Although earlier engraftment is seen when cells from GCSF-mobilized blood are transplanted than when bone marrow is transplanted, administration of GCSF to patients with SCD can cause significant morbidity. We tested whether primitive hematopoietic progenitors are spontaneously mobilized in the blood of patients with SCD during acute crisis (AC-SCD patients). The frequency of myeloid-lymphoid–initiating cells (ML-ICs) and SCID-repopulating cells (SRCs) was significantly higher in blood from AC-SCD patients than in blood from patients with steady-state SCD or from normal donors. The presence of SRCs in peripheral blood was not associated with detection of long-term culture–initiating cells, consistent with the notion that SRCs are more primitive than long-term culture–initiating cells. As ML-ICs and SRCs were both detected in blood of AC-SCD patients only, these assays may both measure primitive progenitors. The frequency of ML-ICs also correlated with increases in stem cell factor, GCSF, and IL-8 levels in AC-SCD compared with steady-state SCD and normal-donor sera. Because significant numbers of ML-ICs and SRCs are mobilized in the blood without exogenous cytokine treatment during acute crisis of SCD, collection of peripheral blood progenitors during crisis may yield a source of autologous HSCs suitable for ex-vivo correction by gene therapy approaches and subsequent transplantation.
Christopher E.D. Lamming, Lance Augustin, Mark Blackstad, Troy C. Lund, Robert P. Hebbel, Catherine M. Verfaillie