Substance P stimulates the recovery of bone marrow after the irradiation

The therapeutic use of ionizing radiation (e.g., X-rays and γ-rays) needs to inflict minimal damage on non-target tissue. Recent studies have shown that substance P (SP) mediates multiple activities in various cell types, including cell proliferation, anti-apoptotic responses, and inflammatory processes. The present study investigated the effects of SP on γ-irradiated bone marrow stem cells (BMSCs). In mouse bone marrow extracts, SP prolonged activation of Erk1/2 and enhanced Bcl-2 expression, but attenuated the activation of apoptotic molecules (e.g., p38 and cleaved caspase-3) and down-regulated Bax. We also observed that SP-decreased apoptotic cell death and stimulated cell proliferation in γ-irradiated mouse bone marrow tissues through TUNEL assay and PCNA analysis. To determine how SP affects bone marrow stem cell populations, mouse bone marrow cells were isolated and colony-forming unit (CFU) of mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs) was estimated. SP-pretreated ones showed higher CFUs of MSC and HSC than untreated ones. Furthermore, when SP was pretreated in cultured human MSC, it significantly decreased apoptotic cells at 48 and 72 h after γ-irradiation. Compared with untreated cells, SP-treated human MSCs showed reduced cleavage of apoptotic molecules such as caspase-8, -9, -3, and poly ADP-ribose polymerase (PARP). Thus, our results suggest that SP alleviates γ-radiation-induced damage to mouse BMSCs and human MSCs via regulation of the apoptotic pathway.     

Effect of autologous marrow transplantation on bone marrow recovery following large-field fractionated irradiation of dogs

After large-field fractionated irradiation of dogs at a cumulative dose of 54 Gy, a stable bone marrow depletion occurs persisting for a year following irradiation. The automyelotransplantation after the end of the exposure elicits a transient recovery of the exposed bone marrow, 1.5-2 months after the beginning of irradiation, followed by a secondary depletion of the exposed haemopoietic sites. The control and the automyelotransplanted animals exhibited bone marrow recovery one year and six months after irradiation, respectively, the cellularity being maintained at a high level for 3 years of observation.     

Transferrin binding of bone marrow cells and metabolic activity of erythrocytes after 5 Gy irradiation

The effect of total body irradiation (5 Gy) on functional mouse erythroid lineage has been studied. The transferrin binding capacity by bone marrow cells and the activity of glycolytic regulatory enzymes and intracellular levels of 2,3 bisphosphoglycerate in peripheral blood erythrocytes have been determined. Results obtained along one year post-irradiation period suggest a complete recovery in the erythroid cell lineage with respect to the biological endpoints investigated.     

Accelerated marrow recovery following total-body irradiation after treatment with vincristine, lithium or combined vincristine-lithium

Accelerated post-irradiation recovery of hematopoietic marrow has been reported following treatment with lithium (Li) or vincristine (VcR). Because these two agents appear to exert their effects on different, albeit overlapping, hematopoietic populations, it was felt that combining them might lead to a wider spectrum of enhanced post-irradiation marrow regeneration. Results demonstrated that an accelerated recovery, which appeared to be additive in nature, was observed in the marrow following combined VcR-Li/4.5 Gy total-body irradiation. The combined schedule significantly enhanced post-irradiation recovery of white blood cells, 12-day spleen colony-forming units, erythroid burst-forming units, and fibroblastic colony-forming units over radiation alone; and recovery of marrow cellularity, multipotential colony-forming units (CFU-gemm) and granulocytic/monocytic colony-forming units (CFU-gm) over both radiation alone and either drug given singly with the 4.5 Gy. In addition, while data on the ability of regenerating stroma to support CFU-gm and CFU-gemm did not suggest that VcR was acting to enhance post-irradiation marrow recovery by increasing stromal production of hematopoietic growth factors, Li did appear to increase production of one or more of these factors, and this may be part of its mechanism of action.     

Endocrine dysfunction after total body irradiation and bone marrow transplantation

The present report describes our data regarding changes of endocrine parameters after total body irradiation (TBI) and bone marrow transplantation (BMT). Endocrine glands are usually resistant to irradiation under morphological aspects. But new methods of determination and sensitive tests were developed in the last few years. Now it is possible to detect already small functional changes. Endocrine studies in the course of the disease were followed serially at 16 patients with TBI and BMT. Pretransplant conditioning consisted of single-dose irradiation combined with a high-dose, short-term chemotherapy. Reactions of the endocrine system showed a defined temporary order. Changes of ACTH and cortisol were in the beginning. The pituitary-adrenal cortex system responds in a different way. The pituitary-thyroid system develop a short-term "low-T3-syndrome" reflecting the extreme stress of the organism. At the same time we obtained an increase of thyroxine. Testosterone and luteotropic hormone, the sexual steroids showed levels representing a primary gonadal insufficiency. The studies in the posttransplant period yielded a return to the normal range at most of the hormonal levels with the exception of the sexual steroids. Sterility is one of the late effects of TBI. A tendency towards hypothyroidism could be noticed in some cases being only subclinical forms. Reasons and possible therapy are discussed.     

Characterization of spontaneous bone marrow recovery after sublethal total body irradiation: importance of the osteoblastic/adipocytic balance

Many studies have already examined the hematopoietic recovery after irradiation but paid with very little attention to the bone marrow microenvironment. Nonetheless previous studies in a murine model of reversible radio-induced bone marrow aplasia have shown a significant increase in alkaline phosphatase activity (ALP) prior to hematopoietic regeneration. This increase in ALP activity was not due to cell proliferation but could be attributed to modifications of the properties of mesenchymal stem cells (MSC). We thus undertook a study to assess the kinetics of the evolution of MSC correlated to their hematopoietic supportive capacities in mice treated with sub lethal total body irradiation. In our study, colony-forming units-fibroblasts (CFU-Fs) assay showed a significant MSC rate increase in irradiated bone marrows. CFU-Fs colonies still possessed differentiation capacities of MSC but colonies from mice sacrificed 3 days after irradiation displayed high rates of ALP activity and a transient increase in osteoblastic markers expression while pparγ and neuropilin-1 decreased. Hematopoietic supportive capacities of CFU-Fs were also modified: as compared to controls, irradiated CFU-Fs significantly increased the proliferation rate of hematopoietic precursors and accelerated the differentiation toward the granulocytic lineage. Our data provide the first evidence of the key role exerted by the balance between osteoblasts and adipocytes in spontaneous bone marrow regeneration. First, (pre)osteoblast differentiation from MSC stimulated hematopoietic precursor's proliferation and granulopoietic regeneration. Then, in a second time (pre)osteoblasts progressively disappeared in favour of adipocytic cells which down regulated the proliferation and granulocytic differentiation and then contributed to a return to pre-irradiation conditions.     

Effect of fractionated thymocytes from intact and irradiated mice on CFU recovery in the bone marrow after sublethal irradiation

In studying the influence of thymocytes fractionated by their size in the ficoll density gradient on the CFUs content of the irradiated mouse bone marrow, two subpopulations of T-cells were isolated: the administration of the first thymocyte subpopulation decreased the CFUs content during the postirradiation recovery period while thymocytes of the second subpopulation increased the content of CFUs in the bone marrow. When thymocytes of mice exposed to low-level radiation were separated a considerable stimulatory effect was produced by certain thymus cell fractions on the number of CFUs in the bone marrow of exposed recipients; no inhibitory effect was registered.     

Morphological changes after large-field irradiation of dogs and autologous bone marrow transplantation

The effect of an automyelotransplant taken from a nonirradiated area of bone marrow has been studied after large fields irradiation in dogs. Certain changes occurring in the hemopoietic organs and in some other vitally important organs have been revealed. The automyelotransplantation contributes to a quicker repopulation of the bone marrow and stimulates lymphoid hemopoiesis in the spleen; that plays a positive role in overcoming the bone marrow syndrome at radiation illness. In other organs (gastrointestinal tract, kidneys, lungs, heart) given various doses of irradiation, in the control and test (with automyelotransplantation) groups similar morphological changes have been revealed.     

Combination of drugs elevating extracellular adenosine with granulocyte colony-stimulating factor promotes granulopoietic recovery in the murine bone marrow after 5-fluorouracil treatment.

Combined administration of drugs elevating extracellular adenosine, namely dipyridamole and adenosine monophosphate, together with granulocyte colony-stimulating factor was shown to enhance granulopoietic recovery in the bone marrow of mice treated with 5-fluorouracil. Enhanced regeneration was found both at the level of hematopoietic progenitor cells for granulocytes and macrophages and in the compartment of morphologically recognizable granulocyte precursors. The results might have positive clinical impact. The adjunct use of drugs elevating extracellular adenosine might reduce the cost expenditure of therapy with granulocyte colony-stimulating factor.     

Immune recovery following bone marrow transplantation

83 patients undergoing allogeneic or autologous BMT because of haematologic malignancies have been studied before and after transplantation at different intervals. The determinations consisted of lymphocyte counts, E-rosetting, lymphoblastic response, evaluation of serum immunoglobulin levels, skin testing, and in a smaller part of the patients surface marker studies using monoclonal antibodies of the BL-series. At first after BMT the lymphocyte and T cell counts went to normal between 4-18 weeks post transplant, about 4 weeks earlier in autologous than in allogeneic BMT. T suppressor cells showed an early increase compared to T helper cells which normalized much slower about 6 months after BMT. Lymphoblastic responses, however, tended to normal not before the second half of the first year both in autologous and allogeneic transplantation. Skin test reactivity became normal during the 2nd and 3rd year posttransplant, which was more complete in autologous than in allogeneic BMT. The IgG and IgM levels were depressed for half a year and IgA levels for 2 years. The most striking aspect was the multiphase course of lymphoblastic response in every individual patient. We suggest this to be the expression of sequential differentiation of donor lymphocytes.     

Recovery course in mouse spleen and bone marrow after continuous irradiation.

The paper deals with the recovery process of some parameters in the spleen and bone marrow till day 60 after continuous irradiation with a daily dose of 476.5 mGy (50 R), 957 mGy (100 R) and 4785 mGy (500 R) up to the total accumulated dose of 9570 mGy (1000 R). The recovery process in the spleen and bone marrow are relatively significant and completed till day 28 or 60 respectively after irradiation.     

FADD deficiency impairs early hematopoiesis in the bone marrow

Signal transduction mediated by Fas-associated death domain protein (FADD) represents a paradigm of coregulation of apoptosis and cellular proliferation. During apoptotic signaling induced by death receptors including Fas, FADD is required for the recruitment and activation of caspase 8. In addition, a death receptor-independent function of FADD is essential for embryogenesis. In previous studies, FADD deficiency in embryonic stem cells resulted in a complete lack of B cells and dramatically reduced T cell numbers, as shown by Rag1(-/-) blastocyst complementation assays. However, T-specific FADD-deficient mice contained normal numbers of thymocytes and slightly reduced peripheral T cell numbers, whereas B cell-specific deletion of FADD led to increased peripheral B cell numbers. It remains undetermined what impact an FADD deficiency has on hematopoietic stem cells and progenitors. The current study analyzed the effect of simultaneous deletion of FADD in multiple cell types, including bone marrow cells, by using the IFN-inducible Mx1-cre transgene. The resulting FADD mutant mice did not develop lymphoproliferation diseases, unlike Fas-deficient mice. Instead, a time-dependent depletion of peripheral FADD-deficient lymphocytes was observed. In the bone marrow, a lack of FADD led to a dramatic decrease in the hematopoietic stem cells and progenitor-enriched population. Furthermore, FADD-deficient bone marrow cells were defective in their ability to generate lymphoid, myeloid, and erythroid cells. Thus, the results revealed a temporal requirement for FADD. Although dispensable during lymphopoiesis post lineage commitment, FADD plays a critical role in early hematopoietic stages in the bone marrow.     

Morphological changes in spleen, bone marrow and blood of rats after continuous gamma irradiation and indomethacin treatment.

A possibility of modifying the radiation damage of haematopoiesis by indomethacin administered during continuous irradiation was followed. Indomethacin was given in drinking water (average dose of 740.7 micrograms/kg per day) within 7-days continuous irradiation with gamma rays (a daily dose rate of 2.055 Gy, total accumulated dose of 14.385 Gy). Under the given conditions no marked protective effect of indomethacin on haematopoiesis was found with the exception of mild stimulation of myelopoiesis and an increased release of developmentally younger cells of myeloid and erythroid series to the peripheral blood as well.     

Lack of nontargeted effects in murine bone marrow after low-dose in vivo X irradiation

Exposure to high doses of ionizing radiation unequivocally produces adverse health effects including malignancy. At low doses the situation is much less clear, because effects are generally too small to be estimated directly by epidemiology, and extrapolation of risk and establishment of international rules and standards rely on the linear no-threshold (LNT) concept. Claims that low doses are more damaging than would be expected from LNT have been made on the basis of in vitro studies of nontargeted bystander effects and genomic instability, but relevant investigations of primary cells and tissues are limited. Here we show that after low-dose low-LET in vivo radiation exposures in the 0-100-mGy range of murine bone marrow there is no evidence of a bystander effect, assessed by p53 pathway signaling, nor is there any evidence for longer-term chromosomal instability in the bone marrow at doses below 1000 mGy. The data are not consistent with speculations based on in vitro nontargeted effects that low-dose X radiation is more damaging than would be expected from linear extrapolation.