Biomedical subjects

M Comisso

Publications and source records attributed to M Comisso.

15 recordsLinked to original sources

PubMed1996

CD28-mediated cytotoxicity of YT natural killer cells on B7-positive targets induces rapid necrotic death independent of granule exocytosis.

The mechanisms leading to target cell killing by the human NK-like cell line YT2C2 have been studied. YT2C2 cells express CD28 antigen and kill B7-expressing targets by a CD28-mediated mechanism which is inhibited by anti-CD28 mAb (CD28.2). The lysis of B7-negative targets, which are also killed by YT2C2, is insensitive to CD28.2, but can be inhibited by cyclosporin A (CsA). CsA reduces degranulation in YT2C2 as measured by BLT-esterase release assays. A total suppression of B7-negative cell lysis was observed in the presence of EGTA, which blocks both degranulation and perforin polymerization, confirming that lysis of this type of target depends solely upon granule exocytosis. In contrast, an additional extracellular EGTA-resistant component in B7-positive target killing was evidenced. These results were consistently obtained with a panel of B7-positive and B7-negative targets, including a Jurkat subclone transfected to express B7 and its parental cell line. Ca2+-independent killing was completed during the first hour of the cytotoxicity assay, whereas EGTA-sensitive lysis increased throughout the whole incubation time. These two lytic mechanisms used by YT2C2 were found to induce two different modes of cell death. Extracellular Ca2+-dependent killing caused apoptotic death in both B7-positive and B7-negative targets, whereas the EGTA-resistant cytolytic pathway, observed exclusively with B7-positive targets, led to necrosis. CD28 triggering in YT2C2 induces, therefore, an additional mechanism of cell killing, independent of granule exocytosis, the nature of which remains to be identified.

Antibodies, Monoclonal↗

PubMed1995

Effects of norcantharidin, a protein phosphatase type-2A inhibitor, on the growth of normal and malignant haemopoietic cells.

Cantharidin is a natural toxin that inhibits protein phosphatase type 2A (PP2A) and has antitumour effects in man. We have studied the synthetic analogue, norcantharidin (NCTD), which has less nephrotoxic and phlogogenic side-effects, investigating the effects on the normal haemopoietic system and leukaemia cell growth. Daily intraperitoneal (i.p.) injection of NCTD induced dose and circadian time-dependent transient leucocytosis in normal mice, but did not accelerate bone marrow (BM) regeneration, or have haemopoietic offe-effects following chronic administration. NCTD stimulated the cell cycle progression of granulocyte-macrophage colony-forming cells (GM-CFC), stimulated DNA synthesis and increased the frequency of mitotic cells in short-term human BM cultures. NCTD also stimulated the production of interleukin (IL)-1 beta, colony stimulating activity (CSA) and tumour necrosis factor (TNF)-alpha. Continuous in vitro NCTD treatment, however, inhibited both DNA synthesis and GM-CFC growth. Fluorescence-activated cell sorting (FACS) analysis of DNA profiles and cytological studies in HL-60, K-562 or MRC5V2 (fibroblast) cells indicated that low doses of NCTD accelerated the G1/S phase transition, while higher doses or prolonged incubations inhibited the cell cycle at the G2/M phases or during the formation of postmitotic daughter cells. Electron microscopy revealed that NCTD impaired the neogenesis of chromatin material and nuclear membrane during the M/G1 phase transition in K-562 cells. The biphasic effect of NCTD may be due to inhibition of PP2A activity, which regulates the cell cycle, both at the restriction point and at the G2 and M phases. Our data provide new insight into the cellular and molecular actions of NCTD, and partly explain its therapeutical effects in cancer patients.

Animals↗

PubMed1995

The hematon, a morphogenetic functional complex in mammalian bone marrow, involves erythroblastic islands and granulocytic cobblestones.

The development of pluripotential hematopoietic stem cells (PHSC) requires the continuous support provided by the bone tissue and bone marrow (BM) stromal cells. The basic rule of spatial and temporal organization of the distinct stromal cells and differentiating hematopoietic cells in the course of development, regenerative morphogenesis, or under homeostasis is still poorly understood. We have identified a cohort of preformed, multicellular aggregates in human BM aspirates that we have called hematons. This study shows that homologous hematon complexes can be isolated from the femoral BM shaft of normal mice. Cytologic analysis showed that both human and mouse hematons contained finely arborized endothelial cells, fibroblasts, preadipocytes, lipid-laden cells, and resident macrophages. This stromal cell web was tightly packed with hematopoietic cells comprising primitive cells with marrow-repopulating ability (MRA); day-8 and -12 colony-forming unit-spleen (CFU-S8 and -S12) in the mouse hematon; and high proliferative potential colony-forming cell (HPP-CFC), burst-forming unit-erythroid (BFU-E), granulocyte-macrophage-CFU (GM-CFU), as well as differentiated postmitotic cell populations in both human and mouse hematons. A cohort of single hematons produced a large, but variable, number of myeloid and erythroid cells, as well as megakaryocytes, in organotypic microculture, indicating the heterogenous growth potential of individual hematons. Each hematon developed into a complex, adherent colony in long-term liquid culture, which involves erythroblastic islands and granulocytic cobblestones. The hematons, isolated from 5-fluorouracil (5-FU)-treated mice, contained more HPP-CFC, BFU-E, and GM-CFU populations than the buffy coat (BC) fraction and produced significantly more CFU than normal hematons in organotypic microcultures. The present results provide further support for our hypothesis that the hematon is a tissue-specific complex structure that plays a critical roles in the maintenance of homeostasis and in the regenerative morphogenesis of mammalian BM.

Animals↗

PubMed1994

Spontaneous or imposed circadian changes in plasma concentrations of 5-fluorouracil coadministered with folinic acid and oxaliplatin: relationship with mucosal toxicity in patients with cancer.

Pharmacokinetics of total platinum, 5-fluorouracil, l-folinic and d-folinic acid, and 5-methyltetrahydrofolate were studied in plasma from nine patients with advanced colorectal cancer treated with oxaliplatin (20 mg/m2/day), 5-fluorouracil (600 mg/m2/day), and folinic acid (300 mg/m2/day). Drugs were administered with a programmable-in-time pump by continuous infusion for 5 days. We compared two drug delivery schedules: constant rate versus chronomodulated rate with peak of oxaliplatin at 4 pm and peak of 5-fluorouracil and folinic acid at 4 am. In the chronomodulated schedule, plasma concentrations of the drugs paralleled the pump functioning: maximum platinum concentration near 4 pm, and maximum 5-fluorouracil and folate concentrations near 4 am. When drugs were administered at a constant rate, mean plasma concentration of 5-fluorouracil varied in a circadian manner each treatment day, that is, a peak at 4 am (approximately 800 ng/ml) and a trough at 1 pm (approximately 100 ng/ml). Mean plasma levels of total platinum and folate compounds increased over the first 24 hours. Total platinum mean level and that of the inactive d-folinic acid isomer reached a constant plasma concentration, whereas biologically active folates exhibited circadian variation in their plasma concentrations (peak around 7 am, trough near 6 pm, and amplitude approximately 10%). Severe mucositis was exhibited by all four patients on the flat schedule, but only by one on the chronomodulated schedule (p < 0.008). Individual pharmacokinetic and toxicity data showed that patients with circadian rhythms in 5-fluorouracil concentrations were least sensitive to 5-fluorouracil-related toxicity. Thus amplification or induction of such rhythm in 5-fluorouracil exposure may permit dose escalation.

Adult↗

PubMed1992

Combined differentiation therapy in myelodysplastic syndrome with retinoid acid, 1 alpha,25 dihydroxyvitamin D3, and prednisone.

The myelodysplastic syndrome (MDPS) provides an opportunity for identifying host factors (genetic, endocrine, immune) involved in initiation and progression of preleukemia into frank acute myeloid leukemia. The aim of this study was to identify bone marrow (BM) cellular and humoral dysfunctions central to the development of MDPS and useful in therapeutic follow-up studies. Our preclinical studies have shown that (1) the characteristic stromal cell composition of the normal BM microenvironment was impaired in MDPS and in AML in 67 and 86% of the cases, respectively; (2) the 1 alpha,25(OH)2D3 concentration in BM plasma was abnormal in 50% of MDPS and 30% of AML; and (3) an inverse correlation existed in MDPS between the 1 alpha,25(OH)2D3 concentration and the frequency of F-CFU, (r = 0.41, p < 0.02), suggestive of a regulatory interaction between this secosteroid hormone and BM stromal cells. The analysis of clonal extinction of BM blast cells in response to all trans retinoic acid (RA), 1 alpha,25(OH)2D3, and colony stimulating factors (PHA-LCM), either alone or in various combinations, revealed individual patterns of responses in the cases of MDPS or AML. The results indicate the necessity for preclinical studies to select patients for combined differentiation therapy. Our ongoing clinical trials suggest that RA (Roaccutan, 20 mg/day continuously) as induction therapy, followed at weeks 6 to 8 by prednisone (40 mg/day for 15 days) and 1 alpha,25(OH)2D3 (Rocaltrol, 3 x 0.25 micrograms/day for 3 months) may induce a long-lasting hematological remission in MDPS.

Bone Marrow↗

PubMed1991

Roles for the heliodynamic hormones, all trans retinoic acid and 1 alpha, 25-dihydroxyvitamin D3, in control of the hematopoietic cell cycle.

It is now well established that the production of primary hematopoietic cells is controlled at different levels of the biological organization. Bone marrow (BM) stromal cells, the extracellular matrix (ECM), polypeptide hematopoietic growth factors (HGF) as well as endogenous cell-division cycle (CDC) related factors play a dominant role in this control. Recent information suggest that the 2 lipophilic hormones, transRA and 1 alpha,25D3, depending on and/or perhaps mediating solar energy, play a role in the maintenance of BM homeostasis. Here we show that both transRA and 1 alpha,25D3: a) modulate the growth and/or stimulate the adipocytic differentiation of fibroblastic stromal cells (F-CFU); b) inhibit the synthesis and extracellular processing but stimulate the solubilization of matrix collagen; c) modulate the clonal growth of myeloid progenitor cells (GM-CFU) in synergy with HGFs; and d) inhibit the production of lactic acid in standard, normal long-term BM cultures (LTBMC). Comparative analysis of normal, preleukemic and leukemic BM cells in LTBMC indicated a positive correlation between the induction of terminal differentiation and reduced lactate production elicited by transRA or 1 alpha,25D3. These results raise a hypothesis according to which the terminal differentiation induced by the helicodynamic hormones is dependent on the mitochondrial aerobic ATP-generating system whose impairment may be a critical step during the process of leukemic transformation.

Bone Marrow↗

PubMed1991

Retinoic acid in mono- or combined differentiation therapy of myelodysplasia and acute promyelocytic leukemia.

Myelodysplastic preleukemic syndromes (MDPS) and acute promyelocytic leukemia (APL) share a surprising in vivo sensitivity to the hormonally acting 13 cis or all trans retinoic acids (transRA). Here we show that transRA as a monotherapeutic agent induced a stable remission in APL at the third relapse. In MDPS, treatment with prednisone and 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25D3) 13 cis RA induced a long-lasting hematological remission. Initially both patients had an impaired BM microenvironment which regenerated on retinoid therapy as judged by reappearance of the Hematon fraction in the BM aspirates. Our preclinical experiments using long-term liquid BM cultures (LTBMC) indicated that several individual patterns of growth and differentiation responses can be induced by combinations of transRA, 1 alpha,25D3 and hemopoietic growth factors (HGFs). The biological responses may vary from complete clonal extinction to a significant growth stimulation of the leukemic blast cell populations. These results further support the importance of preclinical studies in selecting "good" responders for, and excluding "poor" responders from protocols using differentiation therapy.

Bone Marrow↗

PubMed1991

Modulation of bone marrow cell functions in vitro by bestatin (ubenimex).

Bestatin (ubenimex), the microbial leucil-aminopeptidase B inhibitor, has been shown previously to stimulate both interleukin-1 (IL-1) and IL-2 production and to enhance T-cell, as well as macrophage mediated immunoreaction when administered in vivo in mice. Here we show that although Bestatin has no direct growth stimulatory activity, it enhances the growth of GM-CFU populations in semisolide culture and stimulates the cell production in liquide organotypic Hematon cultures in synergy with recombinant human GM-CSF. In long term human bone marrow culture Bestatin accelerated the adipocytic differentiation among colony forming stroma cells (F-CFU). Our data provide further evidences that Bestatin may interact with the hemopoietic cell renewal system at different levels of biological organisation.

Antibiotics, Antineoplastic↗

PubMed1991

Elliptinium, norcantharidin and tetrachlordecaoxide in combined chemo-immunotherapy prolong the survival of Friend-virus-infected mice.

The association of several drugs with different target specificities has long been proven to be more efficient than one single agent in the treatment of cancer. This strategy might also be of benefit in the cure of retrovirus-induced diseases. The effectiveness of several drug combinations was evaluated on DBA/2 mice injected with Friend leukaemia virus (FLV). Elliptinium (ELP), a known chemotherapeutic agent with possible antiviral activity, was given in association with norcantharidin (NCTD) (shown previously to increase the cytotoxic potential of human lymphocytes) and/or in association with tetrachlordecaoxide (TCDO), which augments both humoral and cellular immune responses. ELP alone at a dose of 0.2 mg/kg in long-term treatment significantly increased the survival of mice infected by FLV. When ELP, TCDO (2 micrograms/kg) and NCTD (2 mg/kg) were given together, the survival time was prolonged 1.6 times and 2 times as compared to the group treated by ELP alone or to non-treated controls, respectively. Moreover, the combined treatment gave more effective inhibition of hepatomegaly than ELP alone, suggesting that this protocol might have an organ-specific effect and might suppress the leukaemogenesis induced by FLV in some erythropoietic organs. These results indicate that a chemotherapeutic agent (ELP) associated with two immunomodulatory substances (NCTD and TCDO) is more effective than chemotherapy alone in controlling retroviral infection and in the prolongation of survival. These data taken together suggest that the role of the two immunomodulatory agents might be to suppress the retroviral infection synergistically with ELP and enhance immune functions. Possible modes of action are discussed and are under investigation.

Adjuvants, Immunologic↗

PubMed1990

Hematon, a multicellular functional unit in normal human bone marrow: structural organization, hemopoietic activity, and its relationship to myelodysplasia and myeloid leukemias.

An increasing amount of data provides strong evidence for the complex multifactorial control of primary hemopoietic functions. Here we present a new multicellular functional unit, the Hematon, isolated from the light-density floating fraction of normal human bone marrow (BM) aspirates. The Hematon is organized in a compact, three-dimensional spheroid complex from central adipocytes, fibroblastoid cells, and resident macrophages that compartmentalize myeloid, erythroid, and megakaryocyte progenitor cells and their progenies. The Hematon fraction is more than twofold more abundant in progenitor cells when compared to the mononuclear cell (MNC) fraction as gauged by cytological techniques and by analysis of granulocyte-macrophage colony-forming unit (GM-CFU) populations. Individual Hematons may produce, within 2-3 weeks, up to 50,000 hemopoietic cells of different cell lineages in organotypic microcultures. Recombinant human hematopoietic growth factors interleukin 3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), and macrophage colony-stimulating factor (M-CSF) significantly stimulated the endogenous cell production of some but not all of the individually treated Hematons, indicating the heterogeneity of factor-responsive cells within the Hematon population. Comparative observations of 184 BM aspirates support the hypothesis that the presence of Hematons in a BM aspirate correlates positively with homeostatic blood cell production, because the Hematon was present in normal BM (31/40) and it was rare among patients with myelodysplastic syndromes (15/53), acute myeloblastic leukemia (7/39), and chronic myelocytic leukemia (5/52). We suggest that the Hematon represents a unifying model around which the variability of fundamental BM functions and dysfunctions can be explored.

Bone Marrow↗

PubMed1989

The differentiation-promoting potential of a cytostatic fluoro-pyranosyl adriamycin analog (FAD 104).

Acute toxicity to the hematopoietic cell renewal system is a critical side effect of most anticancer agents. Here we compared the effects of FAD-104 to those of the parent compound adriamycin (ADM) and of epi-adriamycin (epi-ADM) on the growth and differentiation of normal as well as leukemic human myeloid progenitor cells. FAD-104 was less toxic to myeloid colony-forming cells (GM-CFU) than ADM or epi-ADM. In addition, FAD-104 but not ADM induced a clonal down-grading in both normal and leukemic blast cells, and it stimulated the terminal differentiation of myeloid leukemia cells. Therefore, FAD-104 may be useful in the treatment of some forms of myeloid leukemia.

Antineoplastic Agents↗

PubMed1988

Hematon: a multicellular functional unit in primary hematopoiesis.

Bone marrow aspirates from healthy donors contain a fraction of low density multicellular spheroids, 100-500 microns in diameter. They are organized in a three-dimensional network consisting of central preadipocytes/adipocytes, mesenchymal and reticular cells, and resident macrophages that are closely associated with myeloid, erythroid and megakaryocyte progenitor cells and with their progenies. These spheroids are 2- to 5- fold more abundant in progenitor cells compared with the whole bone marrow as estimated by monoclonal antibody markers My 10 and T 9, by analysis of granulocyte--macrophage colony forming cells (GM-CFC) and by cytological techniques. They produce terminally differentiated cells in organotypic microcultures. We suggest that a multicellular spheroid may represent the fundamental unit of primary hematopoiesis; we therefore name it hematon. Here we show that the presence of hematons in bone marrow aspirates correlated positively with homeostatic blood cell production: they were present in normal bone marrow (BM) (19/25), and absent in myelodysplasic syndromes (MDPS) (8/21), in acute nonlymphocytic leukemias (ANLL) (3/22) and in chronic myeloid leukemia (CML) (2/28). The hematons were recovered under hematological remission in MDPS and in ANLL, suggesting that they may be dispersed reversibly in certain disease conditions. The hematons represent a unifying model around which the variability in some bone marrow cell functions can be explored.

Bone Marrow↗

PubMed1986

Excess of lympho-reticular cell complexes in the bone marrow linked to T cell mediated dysmyelopoiesis.

The term dysmyelopoietic syndrome (DMPS) covers a variety of closely related disorders with various etiological factors, and characterized by chronic (pan) cytopenias whose prognosis and treatment are still controversial. Despite the recent efforts to identify pathogens, effector cells and soluble cell products involved in the development of this syndrome only a few comprehensive experimental data are available, useful for elaboration of therapeutic regimens. We describe here a patient with DMPS who was refractory to inductive chemotherapy. Initial agar gel culture studies revealed the activity of hematopoiesis inhibitory T cells within the bone marrow that could be suppressed by prednisone both in vitro and in vivo. However another pathological cell features, the excess of an unusual lympho-reticular cell complexes was identified in long-term liquid cultures. These symbiotic cell complexes persisted throughout the disease, despite the prednisone induced hematological remission, suggesting their causative role in the disease, that more recently progressed towards acute myeloid leukemia.

Adult↗

PubMed1985

In vitro induction of CFU-S proliferation by a non viral splenic activity from myeloproliferative sarcoma virus infected mice.

The myeloproliferative sarcoma virus (MPSV) induces a myeloproliferative syndrome in DBA/2 mice. It is characterized by a considerable increase in the number (100-fold) and in the concentration (10-fold) of pluripotent hematopoietic stem cells detected in vivo (CFU-S) in the spleens of infected animals. Prior studies have shown the presence of a mixed-colony promoting activity (MPA) in neoplastic spleens. In the presence of a small quantity of erythropoietin, MPA induces the proliferation and differentiation of pluripotent hematopoietic stem cells, detected in vitro (Mix-CFU). We tested the effect of factors produced by neoplastic spleen cells on the proliferation of day 10 CFU-S and their entry into the cell cycle. This was done by comparing the number of day 10 CFU-S present in suspensions of normal bone marrow cells incubated for 2 days on agar underlays containing cells from either normal or neoplastic spleens. Our results show the existence of an activity secreted by cells from the spleens of MPSV-infected animals which starts CFU-S cycling and which is physically distinct from MPSV. The presence of this activity, whose identity with MPA remains to be proven, would enable us to explain the proliferation of CFU-S in the course of the disease.

Animals↗

PubMed1983

Myeloproliferative syndrome induced by MPSV in DBA/2 mice: presence of a mixed-colonies promoting activity (MPA) in the spleen.

The myeloproliferative syndrome induced by the myeloproliferative sarcoma virus (MPSV) in DBA/2 mice stimulates the proliferation of pluripotent hemopoietic stem cells (HSC) and of progenitors committed toward granulomacrophagic and erythroid cell lines. This stimulation may result from a direct effect of the MPSV on HSC or from an indirect effect via locally secreted factors. Normal isogenic bone marrow cells were incubated in the mixed colony-forming unit system in semisolid medium supplemented with conditioned media obtained after incubating neoplastic spleen cells for 3 days at 37 degrees C. These spleen conditioned media contain an activity that is physically separable from MPSV by ultracentrifugation and which, in the presence of a very low quantity of erythropoietin, can induce in vitro the proliferation and differentiation of pluripotent HSC, detected by this Mix-CFU technique. We termed this activity mixed-colonies promoting activity (MPA). These results suggest that the hyperplasia of the nonlymphoid hematopoietic system in the neoplastic spleen results from an indirect effect of the MPSV on pluripotent HSC via locally secreted factors.

Animals↗