Search PubMed⌕ Search

Biomedical subjects

Peter J Quesenberry

Publications and source records attributed to Peter J Quesenberry.

At least 19 recordsLinked to original sources
PubMed2007

Murine allogeneic in vivo stem cell homing(,).

Stem cell homing has been studied in syngeneic models and appears to be rapid (<1 h) and dependent on cellular adhesion and migration factors. We utilized a full H2-mismatched transplantation model to determine the basics of allogeneic homing. C57BL/6J Lin-Sca-1+ cells were labeled with CFSE and injected in non-myeloablated BALB/c mice. Fluorescent cell detection was via high-speed FACS analysis. Alternatively, B6.SJL whole bone marrow cells were injected in lethally irradiated BALB/c mice (10 Gy). One, 3, 6, and 24 h after transplant, marrow was harvested and cells were either plated for high proliferative potential colony-forming cell (HPP-CFC) assay or secondarily injected into myeloablated (8 Gy) C57BL/6J mice using 10% competing C57BL/6J marrow. Chimerism was evaluated at 8 weeks. CFSE+ cells were detected in the bone marrow 1, 3, and 6 h after injection. The numbers were moderately lower when compared to syngeneic homing possibly due to strain effect. Conversely, utilizing a surrogate or secondary assay, we observed a decline of secondary engraftment of harvested cells over time, but not of HPP-CFC. Combining experiments and normalizing the 1-h time point to 100% (to allow comparison), we observed a mean relative engraftment of 87 +/- 29%, 72 +/- 21%, 84 +/- 35% of the 1 h level at 3, 6, and 24 h respectively. HPP-CFC assay showed no significant variation as a homing surrogate over 1-6 h. These data indicate a rapid homing into allogeneic recipients with a plateau at 1 h. The decline of secondary engraftability over time may indicate a phenotype alteration of homed cells.

Animals↗
PubMed2007

Stem cell continuum: directed differentiation hotspots.

OBJECTIVE: The purpose of this study was to evaluate the technique of stem cell-directed differentiation in the context of cell-cycle position. The hypothesis was that stem cells would have different sensitivities to an identical inductive signal through cell-cycle transit and that this would affect the outcome of its progeny. MATERIALS AND METHODS: Differentiation of murine marrow lineage(negative)rhodamine-123(low-)Hoechst-33342(low) (LRH) stem cells was determined at different points in cell cycle under stimulation by thrombopoietin, flt3 ligand, and steel factor. LRH stem cells were subcultured in granulocyte macrophage colony-stimulating factor, granulocyte colony-stimulating factor, and steel factor at different points in cell cycle and differentiation determined 14 days later. RESULTS: There was a significant, reproducible, and pronounced reversible increase in differentiation to megakaryocytes in early S-phase and to nonproliferative granulocytes in mid S-phase. Megakaryocyte hotspots also were seen on a clonal basis. Elevations of the transcription factor FOG-1 were seen at the hotspot along with increases in Nfe2 and Fli1. CONCLUSIONS: We show that the potential of marrow stem cells to differentiate changes reversibly with cytokine-induced cell-cycle transit, suggesting that stem cell regulation is not based on the classic hierarchical model, but instead on a functional continuum. We propose that there is a tight linkage of commitment to a lineage and a particular phase of cell cycle. Thus, windows of vulnerability for commitment can open and close depending on the phase of cell cycle. These data indicate that stem cell differentiation occurs on a cell-cycle-related continuum with fluctuating windows of transcriptional opportunity.

Animals↗
PubMed2006

Bone marrow production of lung cells: the impact of G-CSF, cardiotoxin, graded doses of irradiation, and subpopulation phenotype.

OBJECTIVE: Previous studies have demonstrated the production of various types of lung cells from marrow cells under diverse experimental conditions. Our aim was to identify some of the variables that influence conversion in the lung. METHODS: In separate experiments, mice received various doses of total-body irradiation followed by transplantation with whole bone marrow or various subpopulations of marrow cells (Lin(-/+), c-kit(-/+), Sca-1(-/+)) from GFP(+) (C57BL/6-TgN[ACTbEGFP]1Osb) mice. Some were given intramuscular cardiotoxin and/or mobilized with granulocyte colony-stimulating factor (G-CSF). RESULTS: The production of pulmonary epithelial cells from engrafted bone marrow was established utilizing green fluorescent protein (GFP) antibody labeling to rule out autofluorescence and deconvolution microscopy to establish the colocaliztion of GFP and cytokeratin and the absence of CD45 in lung samples after transplantation. More donor-derived lung cells (GFP(+)/CD45(-)) were seen with increasing doses of radiation (5.43% of all lung cells, 1200 cGy). In the 900-cGy group, 61.43% of GFP(+)/CD45(-) cells were also cytokeratin(+). Mobilization further increased GFP(+)/CD45(-) cells to 7.88% in radiation-injured mice. Up to 1.67% of lung cells were GFP(+)/CD45(-) in radiation-injured mice transplanted with Lin(-), c-kit(+), or Sca-1(+) marrow cells. Lin(+), c-kit(-), and Sca-1(-) subpopulations did not significantly engraft the lung. CONCLUSIONS: We have established that marrow cells are capable of producing pulmonary epithelial cells and identified radiation dose and G-CSF mobilization as variables influencing the production of lung cells from marrow cells. Furthermore, the putative lung cell-producing marrow cell has the phenotype of a hematopoietic stem cell.

Animals↗
PubMed2006

The continuum model of marrow stem cell regulation.

PURPOSE OF REVIEW: We review the continuum model of stem cell regulation. A series of studies on purified lineage negative rhodamine low Hoechst low murine stem cells driven through cell cycle by cytokine exposure have shown that many phenotypic features show reversible changes with cycle progression. RECENT FINDINGS: We and others have shown that purified murine marrow stem cells are a cycling population. Features that are labile with cycle progression are in-vivo engraftment, progenitor numbers, expression of adhesion proteins and cytokine receptors, global gene expression and differentiation into granulocytes and megakaryocytes. These observations have led to a theory that regulation of hematopoietic stem cells is on a continuum and not in a hierarchy. Out-of-tissue plasticity in which marrow cells show a capacity to produce nonhematopoietic cells in non-marrow tissues also exists. We have shown 'robust' production of lung and skeletal muscle cells by marrow cells in the presence of appropriate tissue injury and demonstrated that the capacity of marrow cells to produce nonhematopoietic cells in the lung also varies reversibly with cell cycle status. SUMMARY: Thus, stem cells show a plastic plasticity and the continuum appears to hold for both nonhematopoietic and hematopoietic lineages.

Animals↗
PubMed2005

Critical variables in the conversion of marrow cells to skeletal muscle.

We have studied conversion of marrow cells to skeletal muscle in cardiotoxin-injured anterior tibialis muscle in a green fluorescent protein (GFP) to C57BL/6 transplantation model and ascertained that total body irradiation (TBI) with establishment of chimerism is a critical factor. Local irradiation has little effect in lower doses and was detrimental at higher doses. Whole body (1000 cGy) with shielding of the leg or a combination of 500 cGy TBI and 500 cGy local radiations was found to give the best results. In non-obese diabetic-severe combined immunodeficient (NOD-SCID) recipients, we were able to show that conversion could occur without radiation, albeit at relatively lower levels. Within 3 days of cardiotoxin injury, GFP-positive mononuclear cells were seen in the muscle, and within 2 weeks GFP-positive muscle fibers were identified. Conversion rates were increased by increasing donor-cell dose. Timing of the cardiotoxin injury relative to the transplantation was critical. These studies show that variables in transplantation and injury are critical features of marrow-to-muscle conversions. Irradiation primarily effects conversion by promoting chimerism. These data may explain the differences in the literature for the frequency of marrow-to-skeletal muscle conversion and can set a platform for future models and perhaps clinical protocols.

Animals↗
PubMed2005

Association of fetal hormone levels with stem cell potential: evidence for early life roots of human cancer.

Intrauterine and perinatal factors have been linked to risk of childhood leukemia, testicular cancer, and breast cancer in the offspring. The pool of stem cells in target tissue has been suggested as a critical factor linking early life exposures to cancer. We examined the relation between intrauterine hormone levels and measurements of stem cell potential in umbilical cord blood. Cord blood donors were 40 women, ages >/=18 years, who delivered, from August 2002 to June 2003, a singleton birth after a gestation of at least 37 weeks. We assayed plasma concentrations of estradiol, unconjugated estriol, testosterone, progesterone, prolactin, sex hormone binding globulin, insulin-like growth factor-I (IGF-I), and IGF binding protein-3. For stem cell potential, we measured concentrations of CD34(+) and CD34(+)CD38(-) cells and granulocyte-macrophage colony-forming unit (CFU-GM). We applied linear regression analysis and controlled for maternal and neonatal characteristics. We found strong positive associations between IGF-I and stem cell measures, 1 SD increase in IGF-I being associated with a 41% increase in CD34(+) (P = 0.008), a 109% increase in CD34(+)CD38(-) (P = 0.005), and a 94% increase in CFU-GM (P = 0.01). Similar associations were observed for IGF binding protein-3. Among steroid hormones, estriol and testosterone were significantly positively associated with CD34(+) and CFU-GM. These findings indicate that levels of growth factors and hormones are strongly associated with stem cell potential in human umbilical cord blood and point to a potential mechanism that may mediate the relationship between in utero exposure to hormones and cancer risk in the offspring.

Antigens, CD↗
PubMed2005

Lineage-negative bone marrow cells travel bidirectionally in the olfactory migratory stream but maintain hematopoietic phenotype.

The mammalian olfactory system is a physiologically plastic region of the brain with the potential to support implanted stem cells. We performed direct injection of lineage-negative (lin-neg), green fluorescent protein-positive (GFP+) bone marrow cells into the olfactory bulb to assess cell survival and motility within the central nervous system (CNS). Before direct injection of 100,000 lin-neg cells, some of the C57/Bl mice received 1,000 cGy brain irradiation with the aim of disabling the endogenous reservoir of periventricular neural progenitor cells. Brain harvest took place up to 2 weeks after cell implantation. Brains were evaluated for presence of GFP positivity via fluorescence microscopy. Many GFP+ cells were identified within the turbinate neuroepithelium, olfactory bulb, and frontal lobe. Most of the cells that had traveled from the implantation site adopted an elongated, arborizing morphology consistent with cellular extensions arrayed in the direction of the rostral migratory stream (RMS). No difference was seen in brain-irradiated versus non-irradiated mice. Antibody staining revealed that these cells did not take on a neural, glial, or endothelial phenotype, while largely retaining their hematopoietic lineage as demonstrated by CD45 positivity.

Animals↗
PubMed2005

Stem cells and pulmonary metamorphosis: new concepts in repair and regeneration.

Adult stem cells are likely to have much more versatile differentiation capabilities than once believed. Numerous studies have appeared over the past decade demonstrating the ability of adult stem cells to differentiate into a variety of cells from non-hematopoietic organs, including the lung. The goal of this review is to provide an overview of the growth factors which are thought to be involved in lung development and disease, describe the cells within the lung that are believed to replace cells that have been injured, review the studies that have demonstrated the transformation of bone marrow-derived stem cells into lung cells, and describe potential clinical applications with respect to human pulmonary disease.

Animals↗
PubMed2005

Perspective: fundamental and clinical concepts on stem cell homing and engraftment: a journey to niches and beyond.

In many ways, the homing of hematopoietic stem cells to bone marrow and other tissues defines these cells and their immediate and long-term fates Once homed, an inevitable series of proliferative and differentiative events presumptively follows. These comments, of course, hold for both homing to marrow, or alternatively, to other nonmarrow tissues. In this review, we will specifically focus on homing and engraftment to bone marrow because this is the best-studied and clinically applicable system.

Animals↗
PubMed2005

Stem cell biology and the plasticity polemic.

Characterization of a cord blood derived unrestricted somatic stem cell (USSC) with capacity to differentiate into hematopoietic and nonhematopoietic tissues in the absence of cell fusion has highlighted the great potential of stem cell plasticity. A great variety of stem cell types have been defined and even the most pure marrow stem cells are highly heterogeneous. Data suggest that stem cells may exist in a continuum with continually and reversibly changing phenotype. These cells also possess a capacity to produce lung, liver, skin, and skeletal muscle under conditions of tissue injury. Arguments raised against the significance of adult marrow to nonmarrow conversions including the importance of cell fusion appear fallacious. We are at the beginning of an exciting and burgeoning field of research with great clinical potential.

Animals↗
PubMed2005

Cellular immune therapy for refractory cancers: novel therapeutic strategies.

OBJECTIVE: Allogeneic stem cell transplantation is curative for certain cancers, but the high doses of chemotherapy and radiotherapy may lead to toxicity. This review summarizes the field of cellular immune therapy using very-low-dose conditioning for refractory cancers. METHODS: In our initial study, we treated 25 patients with refractory cancers with 100 cGy total body irradiation followed by allogeneic, nonmobilized peripheral blood cells. Eighteen patients received sibling and seven patients received unrelated cord blood stem cells. RESULTS: None of the 13 patients with solid tumors achieved donor chimerism or had a sustained response. Twelve patients with hematologic malignancies were treated, 1 received a cord blood transplant and 11 received sibling donor cells. Nine of these 11 patients achieved donor chimerism, ranging from 5% to 100%. Four patients had sustained complete remission of their cancers. The patients who received cord blood transplants did not respond. Development of chimerism correlated with total previous myelotoxic chemotherapy (p < 0.001). We review additional studies in this area, including data in the haploidentical and unrelated donor setting. The data presented comprises studies performed at the four institutions represented by the authors, and a review of other pertinent studies in this area. CONCLUSIONS: Cellular immune therapy is an emerging application of transplantation therapy, which may be appropriate for refractory cancers. New studies in solid tumors, and with alternative donors, will expand the application of this new and promising treatment.

Animals↗
PubMed2005

The stem cell continuum.

Hematopoietic stem cells have been felt to exist in a hierarchical structure with a relatively fixed phenotype at each stage of differentiation. Recent studies on the phenotype of the marrow hematopoietic stem cell indicate that it is not a fixed entity, but rather that it fluctuates and shows marked heterogeneity. Past studies have shown that stem cell engraftment characteristics, adhesion protein, and gene expression varies with the phase of the cell cycle. More recently, we demonstrated that progenitor numbers and differentiation potential also vary reversibly during one cytokine-induced cell cycle transit. We have also shown high levels of conversion of marrow cells to skeletal muscle and lung cells, indicating a different level of plasticity. Recently, we demonstrated that homing to lung and conversion to lung cells in a mouse transplant model also fluctuates reversibly with cell cycle transit. This could be considered plasticity squared. These data indicate that marrow stem cells are regulated on a continuum related to the cell cycle both as to hematopoietic and to nonhematopoietic differentiation.

Cell Cycle↗
PubMed2005

The stem cell continuum: considerations on the heterogeneity and plasticity of marrow stem cells.

Traditional models of hematopoiesis have been hierarchical. Recent evidence showing that marrow stem cells are a cycling population and that the hematopoietic phenotype of these cells reversibly changes with cycle transit have suggested a continuum model of stem cell regulators. Studies on marrow cell conversion to lung cells have extended this continuum to cycle-related differentiation into nonhematopoietic stem cells. We postulate that stem cells transiting cell cycle continually change their chromatin structure, thus providing different windows of transcriptional opportunity and a continually changing phenotype. Final outcomes with this continuum model would be determined by the specific chromatin state of the cell and the presence of specific differentiation inducers.

Bone Marrow Cells↗
PubMed2004

Intrinsic hematopoietic stem cell/progenitor plasticity: Inversions.

Traditional concepts indicate that stem cells give rise to progenitor cells in a hierarchical system. We studied murine engraftable stem cells (ESCs) and progenitors in in vitro and found that ESC and progenitors exist in a reversible continuum, rather then a hierarchy. B6.SJL and BALB/c marrow cells were serially cultured with thrombopoietin (TPO), FLT-3 ligand (FLT-3L), and steel factor through cell cycle. Progenitors (high-proliferative potential colony-forming cells (HPP-CFC) and colony-forming unit culture (CFU-c)) and ESC capacity was determined. The cell cycle status of purified lineage(negative)rhodamine(low)Hoechst(low) stem cells was determined under the same conditions using tritiated thymidine incorporation and cell counts. We found an inverse relationship between progenitors and ESC, which occurred during the first cell cycle transit and was reversible. We have termed these progenitor/stem cell inversions and found that these inversions were consistently seen at 28-32 h of culture, representing early S-phase. We observed 13 major reversible increases in progenitor numbers from one time-point to another during the first cell cycle transit; this was coupled with 11 major ESC decreases and in 2 instances ESC were at baseline. These studies indicate that primitive marrow cells reversibly shift from ESC to progenitors without differentiation occurring. They exist as a fluctuating continuum.

Animals↗
PubMed2004

Circadian variations of bone marrow engraftability.

Circadian rhythms exist for hematopoiesis, but little is known about circadian variation of bone marrow engraftability and host "acceptability". Using a B6.SJL to C57BL/6J congenic transplant model, we chose 3-times with light on: Hours After Light Onset (HALO) 4, 8, and 12 and 3-times with light off: HALO 16, 20, and 24. The mice were conditioned on a 12-h light/dark cycles. Recipient mice (100 cGy) received 40 million cells. We demonstrated a significant variation of bone marrow engraftability into bone marrow, spleen, and thymus when donor animals were subjected to changes in their light/dark cycles. Two statistically significant nadirs in all three organs were observed at HALO 8 and 24 in experiments carried out in July, while an identical set of experiments in February analyzing engraftment in marrow and spleen showed nadirs at HALO 8, but not at HALO 24. Marrow progenitors from the July experiments showed nadirs at HALO 12 and 24. The percentage of progenitors in S phase peaked at HALO 8 and 24. Interestingly, there were no changes in the ability of host to accept grafts with changes in the light/dark cycles of host animals. Circadian variations of bone marrow engraftability are important and should be considered in bone marrow transplant strategies.

Animals↗
PubMed2004

Chromatin remodeling and stem cell theory of relativity.

The field of stem cell biology is currently being redefined. Stem cell (hematopoietic and non-hematopoietic) differentiation has been considered hierarchical in nature, but recent data suggest that there is no progenitor/stem cell hierarchy, but rather a reversible continuum. The stem cell (hematopoietic and non-hematopoietic) phenotype, the total differentiation capacity (hematopoietic and non-hematopoietic), gene expression as well as other stem cell functional characteristics (homing, receptor and adhesion molecule expression) vary throughout a cell-cycle transit widely. This seems to be dependent on shifting chromatin and gene expression with cell-cycle transit. The published data on DNA methylation, histone acetylation, and also RNAi, the major regulators of gene expression, conjoins very well and provides an explanation for the major issues of stem cell biology. Those features of stem cells mentioned above can be rather difficult to apprehend when a classical hierarchy biology view is applied, but they become clear and easier to understand once they are correlated with the underlining epigenetic changes. We are entering a new era of stem cell biology the era of "chromatinomics." We are one step closer to the practical use of cellular therapy for degenerative diseases.

Animals↗