Biomedical subjects

Ronald Hoffman

Publications and source records attributed to Ronald Hoffman.

27 records · Page 2Linked to original sources

PubMed2004

Expression of an anti-sickling beta-globin in human erythroblasts derived from retrovirally transduced primitive normal and sickle cell disease hematopoietic cells.

OBJECTIVE: Recent improvements in human beta-globin vector design have fueled interest in gene therapy approaches to the treatment of human thalassemia and sickle cell disease (SCD). The present study was undertaken to determine whether human beta-globin mRNA and protein could be obtained in the erythroid progeny of more primitive human target cells transduced with a retrovirus containing murine stem cell virus long terminal repeats, a phosphoglycerate kinase promoter driving the expression of a green fluorescence protein (GFP) cDNA, and an anti-sickling beta-globin (beta87(+)) gene under the control of an HS2, HS3, HS4 enhancer cassette. MATERIALS AND METHODS: A two-step pseudotyping strategy was devised to obtain useful preparations of this virus. Primitive cells present in normal human cord blood (CB) and adult SCD patients' blood samples were infected and the level of gene transfer (% GFP(+) cells) and erythroid-specific beta87(+)-globin expression assessed. RESULTS: Analysis of the proportion of infected cells that became GFP(+) showed that this virus transduced approximately 50% of initial CD34(+) CB and SCD cells and up to 23% of cells able to regenerate both lymphoid and myeloid cells in sublethally irradiated primary and secondary NOD/SCID mice. beta87(+)-globin transcripts were readily detected in erythroblasts generated from primitive transduced CB cells and SCD progenitors. Evidence of beta87(+)-derived protein in transduced CB cell-derived erythroblasts also was obtained. CONCLUSION: These findings demonstrate that retroviral vector-based gene transfer approaches can be used to achieve human beta-globin protein expression in the erythroid progeny of transplantable human precursors.

Anemia, Sickle Cell↗

PubMed2004

Studies of the route of administration and role of conditioning with radiation on unrelated allogeneic mismatched mesenchymal stem cell engraftment in a nonhuman primate model.

OBJECTIVE: The aim of this study was to examine the effects of the route of administration [intrabone marrow (IBM) vs intravenous (IV)] and the role of conditioning with irradiation in optimizing mesenchymal stem cell (MSC) transplantation. MATERIALS AND METHODS: To determine if irradiation resulted in depletion of colony-forming unit fibroblasts (CFU-F), which might favor the engraftment of donor MSC, the number of CFU-Fs was assayed from animals receiving either hemibody irradiation (HBI) or total body irradiation (TBI). RESULTS: TBI resulted in a marked reduction of CFU-F numbers that spontaneously resolved, whereas animals receiving HBI did not experience depletion of CFU-F. Animals receiving MSC grafts by the IV route had higher numbers of marrow CFU-F. MSC were transduced using retroviral vectors encoding the neomycin resistance gene (Neo(R)) and a second gene encoding either the human soluble tumor necrosis factor receptor (hsTNFRII) or beta-galactosidase (beta-Gal). MSCs were administered by either the IV or IBM route to animals receiving HBI. The Neo(R) transgene was detectable in hematopoietic tissues of all animals and nonhematopoietic tissues in a single animal. Evidence of transgene expression was documented by detection of beta-Gal(+) cells in BM smears and transiently elevated serum levels of hsTNFRII. CONCLUSION: These studies indicate that 1) MSC possess the ability to engraft and persist in an unrelated mismatched allogeneic hosts; 2) 250-cGy HBI did not favor engraftment of MSC; 3) the IBM route was not more effective than the IV route in delivering MSC grafts; and 4) transplanted MSC preferentially localized to the marrow rather than nonhematopoietic tissues.

Animals↗

PubMed2004

Surgical management of complications after hearing aid fitting.

OBJECTIVES: Standard procedures for hearing aid fitting performed in accordance with established guidelines are well tolerated, safe, and effective. In this article, we present unusual complications after hearing aid fitting that required surgical management. METHODS: Four otologists at a major university center with a combined 65 years of experience performed a retrospective analysis of their surgical practice. Six patients were identified that had encountered severe complications from improper earmold fitting that required surgical intervention. RESULTS: One patient had a perforation of the tympanic membrane with earmold material found to have migrated into the middle ear cleft. The tympanic membrane healed spontaneously, resulting in persistent otalgia and a maximum air-bone gap. The earmold cast was successfully removed by means of a tympanomastoidectomy. Two patients with presbycusis and normal ear canals developed eardrum perforations and conductive hearing deficits. In both patients, earmold material was found partially occupying the middle ear cleft and removed by way of a transcanal approach. Three patients with prior canal wall down mastoidectomy defects and narrow external ear canals required microtoscopy under general anesthesia or canaloplasty for removal of impacted material. CONCLUSION: Proper fitting of hearing aids performed by well-trained medical professionals results in a very low incidence of significant complications. Perforation of the tympanic membrane with impaction of earmold material in the middle ear or mastoid bowl may occur and can be successfully managed by standard otologic surgical techniques.

Aged↗

PubMed2003

Effects of 5-aza-2'-deoxycytidine on fetal hemoglobin levels, red cell adhesion, and hematopoietic differentiation in patients with sickle cell disease.

Fetal hemoglobin (HbF) decreases polymerization of sickle hemoglobin (HbS) and improves outcomes in sickle cell disease (SSD). Therefore, a therapeutic goal in SSD is pharmacologic reactivation of HbF. Silencing of the gamma-globin (HbF) gene is associated with DNA methylation. The cytosine analog 5-aza-2'-deoxycytidine (decitabine) hypomethylates DNA by inhibiting DNA methyltransferase. We examined if subcutaneous decitabine could increase HbF levels and improve SSD pathophysiology without cytotoxicity. Eight symptomatic SSD patients resistant or intolerant of standard treatment with hydroxyurea received decitabine 0.2 mg/kg subcutaneously 1 to 3 times per week in 2 cycles of 6-week duration. Treatment decreased neutrophils and increased mean HbF (6.5% to 20.4%, P <.0001) and mean total hemoglobin (76 to 96 g/L [7.6 to 9.6 g/dL], P <.001). Features of vaso-occlusive crisis pathophysiology such as red cell adhesion, endothelial damage, and coagulation pathway activity significantly improved. gamma-Globin gene promoter methylation decreased, and platelets and the proportion of megakaryocytes and erythroid cells in the marrow increased without a decrease in marrow cellularity, consistent with a DNA hypomethylating, noncytotoxic mechanism of action. Weekly subcutaneous decitabine produces cumulative increases in HbF and total hemoglobin through a noncytotoxic mechanism of action. Chronic dosing and sustained increases in hemoglobin F and total hemoglobin levels may be possible. Further studies in SSD and thalassemia are indicated.

Adult↗

PubMed2002

Mesenchymal stem cells suppress lymphocyte proliferation in vitro and prolong skin graft survival in vivo.

OBJECTIVE: Mesenchymal stem cells (MSCs), multipotential cells that reside within the bone marrow, can be induced to differentiate into various components of the marrow microenvironment, such as bone, adipose, and stromal tissues. The bone marrow microenvironment is vital to the development, differentiation, and regulation of the lymphohematopoietic system. We hypothesized that the activities of MSCs in the bone marrow microenvironment might also include immunomodulatory effects on lymphocytes. METHODS: Baboon MSCs were tested in vitro for their ability to elicit a proliferative response from allogeneic lymphocytes, to inhibit an ongoing allogeneic response, and to inhibit a proliferative response to potent T-cell mitogens. In vivo effects were tested by intravenous administration of donor MSCs to MHC-mismatched recipient baboons prior to placement of autologous, donor, and third-party skin grafts. RESULTS: MSCs failed to elicit a proliferative response from allogeneic lymphocytes. MSCs added into a mixed lymphocyte reaction, either on day 0 or on day 3, or to mitogen-stimulated lymphocytes, led to a greater than 50% reduction in proliferative activity. This effect could be maximized by escalating the dose of MSCs and could be reduced with the addition of exogenous IL-2. In vivo administration of MSCs led to prolonged skin graft survival when compared to control animals: 11.3 +/- 0.3 vs 7 +/- 0. CONCLUSIONS: Baboon MSCs have been observed to alter lymphocyte reactivity to allogeneic target cells and tissues. These immunoregulatory features may prove useful in future applications of tissue regeneration and stem cell engineering.

Animals↗

PubMed2002

Primate skeletal muscle contains cells capable of sustaining in vitro hematopoiesis.

OBJECTIVE: Several investigators recently reported that adult murine skeletal muscle cells possess a remarkable capacity to differentiate into hematopoietic cells. We further examined this biologic process by studying the phenotype and in vitro functional behavior of primate skeletal muscle cells. MATERIALS AND METHODS: Muscles from human abortuses as well as fetal and adult baboons were digested enzymatically and mononuclear cell fractions were isolated. Muscle tissue-derived mononuclear cells (mu-TDMNC) were phenotypically characterized. Both short-term and long-term hematopoietic progenitors were assayed from mu-TDMNC using standard techniques. Gene expression patterns characteristic of hematopoietic and endothelial cells were examined in primary and cultured muscle cells. RESULTS: Primate muscle cells were shown to express the CD34 antigen. Such CD34(+) cells were shown to be CD45(-) and desmin(+), indicating they were not of hematopoietic origin. Fetal but not adult muscle cells contained assayable hematopoietic progenitors. In addition, muscles contained an additional class of progenitors that formed colonies composed of blast cells after prolonged incubation (3-4 weeks). A two-step culture system was established that permitted muscle cells to continue to proliferate when exposed to a hematopoietic environment for 8 months. During this prolonged period of time, the generation of CD34(+), CD56(+), CD11b(+), and CD31(+) as well as von Willebrand factor (vWF)(+) cells were observed. CONCLUSIONS: Our studies indicate that although primate muscle cells contain a significant number of CD34(+) cells, they are likely not of hematopoietic origin. Important ontogenic differences in the hematopoietic potential of primate muscle cells were documented. When exposed to appropriate microenvironmental stimuli, mu-TDMNC displayed an extensive proliferative capacity and contained primitive progenitors with the capacity to generate cells in vitro with phenotypic and genetic properties of hematopoietic and endothelial cells for sustained periods of time. Whether this observation can be accounted for by true transdifferentiation of muscle cells or proliferation of reservoirs of hematopoietic and endothelial progenitor cells residing within skeletal muscle remains unresolved.

Age Factors↗

PubMed2002

Quality of life issues in patients with essential thrombocythemia and polycythemia vera.

Essential thrombocythemia and polycythemia vera are both chronic progressive myeloproliferative disorders of insidious onset. If the excessive production of red cells and/or platelets is controlled, patients with these disorders may have prolonged survival. However, the clinical course of these patients can be complicated by a variety of events, including thrombotic episodes, bleeding episodes, arthropathies, pruritus, weakness, weight loss, neurologic impairment, erythromelalgia, fever, abdominal pain, and the life-threatening consequences of progression to myelofibrosis and/or acute leukemia. Effective control of hematopoiesis by phlebotomy or a variety of therapeutic agents has resulted in a reduction or elimination of many of these clinical events, but has not altered the evolution to myelofibrosis or acute leukemia. Use of each of these therapeutic strategies is also associated with a range of adverse events. Monitoring overall survival or a reduction in the frequency of clinical events has previously served as a means of assessing the results of these therapeutic interventions. Quality-of-life instruments have not been applied in a systematic fashion to the evaluation of outcomes in patients with these chronic myeloproliferative disorders. Quality-of-life assessments evaluate not only the state of well-being of a patient that results from an assessment of the individual's ability to perform everyday activities, which are reflective of physical, psychological, and social well-being, but also patient satisfaction with the control of disease and/or treatment-related symptoms. Quality-of-life instruments have been used to assess the clinical course of patients suffering from a variety of disorders, ranging from cancer to renal failure to chronic fatigue syndrome. Information about quality-of-life outcomes can contribute to the evaluation of variations in dose and timing of administration of therapeutic agents. It is possible that the side effects of a particular therapy may outweigh the disease regression achieved with a particular therapy. In the future, quality-of-life instruments may prove useful in prospectively evaluating therapeutic end points in patients with essential thrombocythemia and polycythemia vera.

Humans↗

PubMed1999

A Modified Cage to Minimize Catheter Contamination in the Chronically Catheterized Baboon.

Here we describe modifications made to an 8 sq. ft. aluminum baboon cage to allow removal of a chronically cannulated baboon from the cage without disconnecting the catheter connections. The novel system minimizes potential contamination of the intravenous catheters in an immunosuppressed baboon model and permits removal of the animal for cage changes and transport to a distant facility for experimental manipulation.

Journal Article↗

PubMedDate not supplied

Endothelial precursor cells in the peripheral blood of pregnant women.

OBJECTIVE: To determine whether primitive endothelial precursor cells are present in the peripheral blood of pregnant compared with nonpregnant subjects and whether these precursor cells are of fetal or maternal origin. METHODS: Peripheral blood mononuclear cells from 13 pregnant women in the second trimester and from ten nonpregnant women and men were cultured for 8-10 weeks under conditions that promoted endothelial cell development. Early outgrowth (1 week culture) and late outgrowth (4-6 weeks) colonies were observed, their endothelial nature was investigated, and fluorescence in situ hybridization was performed to determine the origin of the colonies from pregnant women's specimens. RESULTS: Peripheral blood mononuclear cell cultures from all pregnant women and all nonpregnant controls yielded early-outgrowth endothelial cells. Late-outgrowth endothelial cells were observed in 61.5% (eight of 13) of pregnant subjects, but in none of the ten nonpregnant controls (chi(2) test; P <.01). The adherent cells stained positively for von Willebrand factor and incorporated Dil-Ac-LDL, confirming their endothelial origin. Fluorescence in situ hybridization analysis showed only X chromosome-specific signals and no Y chromosome-specific signals in the cells from the late-outgrowth endothelial cells in all pregnant women carrying either a male (n = 5) or a female (n = 8) fetus. CONCLUSION: Primitive endothelial precursor cells are present in most pregnant women during the second trimester. These cells appear to be of maternal origin.

Adult↗