Stem cell niches and other factors that influence the sensitivity of bone marrow to radiation-induced bone cancer and leukaemia in children and adults

Which is better, fluoroscopic-guided or ultrasonic-guided shock wave lithotripsy for pediatric renal stones? Prospective randomized comparative study

OBJECTIVES

To compare the efficacy and clinical outcomes of two different stone localization modalities (fluoroscopic or ultrasonic) in SWL treatment of pediatric renal stones.

PATIENTS AND METHODS

This study was conducted in the period between January 2021 and June 2022 and included 100 children aged 2-16 years who presented with radio-opaque renal pelvic stones < 20 mm. The children were divided in two groups: group I, US-guided (50 patients), and group II, FS-guided SWL (50 patients). SWL was applied under general anesthesia. The follow-up of the patients included a visit every two weeks up to three months.

RESULTS

Even though group II's stone-free rate after one month of follow-up was higher than group I's (90% vs. 84%), no statistically significant difference was found between the groups (p = 0.749). While the success rate was higher in group II than in group I (92% vs. 86%), no statistically significant difference was observed between the two groups (p = 0.338). The complication rate was 28% (14 patients) and 12% (6 patients) in Groups I and II, respectively. However, no significant difference was found between the two groups (p = 0.132).

CONCLUSIONS

SWL is a non-invasive and safe method for treating pediatric renal stones. We recommend the use of the ultrasonic focusing modality in SWL of the pediatric age group, which has similar success rates, avoiding radiation and low complication rate instead of the fluoroscopic focusing modality, which uses ionizing radiation during SWL.

Comparison of ultrasound-assisted and pure fluoroscopy-guided extracorporeal shockwave lithotripsy for renal stones

BACKGROUND

In this study, we aimed to compare the efficacy and clinical outcomes of shock wave lithotripsy (SWL) for patients with renal stones using pure fluoroscopy (FS) or ultrasound-assisted (USa) localization with two lithotripters.

METHODS

We retrospectively identified 425 patients with renal calculi who underwent SWL with either a LiteMed LM-9200 ELMA lithotripter (209 cases), which combined ultrasound and fluoroscopic stone targeting or a Medispec EM-1000 lithotripter machine (216 cases), which used fluoroscopy for stone localization and tracking. The patient demographic data, stone-free rates, stone disintegration rates, retreatment rates and complication rates were analyzed.

RESULTS

The USa group had a significantly higher overall stone-free rate (43.6 vs. 28.2%, p < 0.001) and stone disintegration rate (85.6 vs. 64.3%, p < 0.001), as well as a significantly lower retreatment rate (14.8 vs. 35.6%, p < 0.001) and complication rate (1.9 vs. 5.5%, p = 0.031) compared with the FS group. This superiority remained significant in the stone size < 1 cm stratified group. In the stone size > 1 cm group, the stone-free rate (32.4 vs. 17.8%, p = 0.028), disintegration rate (89.2 vs. 54.8%, p = 0.031) and retreatment rate (21.6 vs. 53.4%, p < 0.001) were still significantly better in the USa group, however there was no significant difference in the complication rate. The most common complication was post-SWL-related flank pain.

CONCLUSION

SWL is a safe and non-invasive way of treating renal stones. This study compared two electromagnetic shock wave machines with different stone tracking systems. LiteMed LM-9200 ELMA lithotripter, which combined ultrasound and fluoroscopic stone targeting outperformed Medispec EM-1000 lithotripter, which used fluoroscopy for stone localization and tracking, with better stone-free rates and disintegration rates, as well as lower retreatment rates and complications with possible reduced radiation exposure.

Mitochondrial adaptation in human mesenchymal stem cells following ionizing radiation

Mitochondria are highly dynamic organelles that respond rapidly to a number of stressors to regulate energy transduction, cell death signaling, and reactive oxygen species generation. We hypothesized that mitochondrial remodeling, comprising both structural and functional alterations, following ionizing radiation (IR) may underlie some of the tenets of radiobiology. Mesenchymal stem cells (MSCs) are precursors of bone marrow stroma and are altered in acute myeloid leukemia and by radiation and chemotherapy. Here, we report on changes in mitochondrial remodeling in human MSCs following X-ray IR. Mitochondrial function was significantly increased in MSCs  4 h after IR as measured by mitochondrial oxygen consumption. Consistent with this elevated functional effect, electron transport chain supercomplexes were also increased in irradiated samples. In addition, mitochondria were significantly, albeit modestly, elongated, as measured by high-throughput automated confocal imaging coupled with automated mitochondrial morphometric analyses. We also demonstrate in fibroblasts that mitochondrial remodeling is required for the adaptation of cells to IR. To determine novel mechanisms involved in mitochondrial remodeling, we performed quantitative proteomics on isolated mitochondria from cells following IR. Label-free quantitative mitochondrial proteomics revealed notable changes in proteins in irradiated samples and identified prosaposin, and potentially its daughter protein saposin-B, as a potential candidate for regulating mitochondrial function following IR. Whereas research into the biologic effects of cellular irradiation has long focused on nuclear DNA effects, our experimental work, along with that of others, is finding that mitochondrial effects may have broader implications in the field of stress adaptation and cell death in cancer (including leukemia) and other disease states.-Patten, D. A., Ouellet, M., Allan, D. S., Germain, M., Baird, S. D., Harper, M.-E., Richardson, R. B. Mitochondrial adaptation in human mesenchymal stem cells following ionizing radiation.

The protective effects of 1,2-propanediol against radiation-induced hematopoietic injury in mice

Agents that provide protection against irradiation-induced hematopoietic injury are urgently needed for radiotherapy. We examined the effects of the small molecule, 1,2-propanediol (PPD), on total body irradiation (TBI)-induced hematopoietic injury in C57BL/6 mice. PPD administration 1 h before TBI significantly increased hematopoietic parameters such as white blood cell, platelet, red blood cell, and lymphocyte counts in vivo and enhanced the survival of mice exposed to TBI (7.0 and 7.5 Gy). PPD administration 1 h before TBI improved bone marrow (BM) and spleen recovery after TBI, with increases in both BM cellularity and spleen index. The number of colony-forming-units in bone marrow mononuclear cells (BMNCs) in vitro also increased significantly. PPD pretreatment increased the numbers of hematopoietic stem cells and hematopoietic progenitor cells in BM. Importantly, PPD also maintained endogenous antioxidant status by decreasing levels of malondialdehyde and increasing the expression of reduced glutathione, superoxide dismutase and catalase in the serum of irradiated mice. PPD alleviated the levels of apoptosis in HSCs induced by TBI, thus increasing the proportion of dividing BMNCs. These results suggest that PPD protects against TBI-induced hematopoietic injury through the increased activities of antioxidant enzymes and the inhibition of apoptosis in HSCs. PPD increased the serum levels of granulocyte-colony stimulating factor and interleukin-6 irrespective of TBI. In conclusion, these data suggest that PPD acts as a radioprotector against radiation-induced hematopoietic injury.

Transmission of clonal chromosomal abnormalities in human hematopoietic stem and progenitor cells surviving radiation exposure

In radiation-induced acute myeloid leukemia (rAML), clonal chromosomal abnormalities are often observed in bone marrow cells of patients, suggesting that their formation is crucial in the development of the disease. Since rAML is considered to originate from hematopoietic stem and progenitor cells (HSPC), we investigated the frequency and spectrum of radiation-induced chromosomal abnormalities in human CD34(+) cells. We then measured stable chromosomal abnormalities, a possible biomarker of leukemia risk, in clonally expanded cell populations which were grown for 14 days in a 3D-matrix (CFU-assay). We compared two radiation qualities used in radiotherapy, sparsely ionizing X-rays and densely ionizing carbon ions (29 and 60-85 keV/μm, doses between 0.5 and 4 Gy). Only a negligible number of de novo arising, unstable aberrations (≤ 0.05 aberrations/cell, 97% breaks) were measured in the descendants of irradiated HSPC. However, stable aberrations were detected in colonies formed by irradiated HSPC. All cells of the affected colonies exhibited one or more identical aberrations, indicating their clonal origin. The majority of the clonal rearrangements (92%) were simple exchanges such as translocations (77%) and pericentric inversions (15%), which are known to contribute to the development of rAML. Carbon ions were more efficient in inducing cell killing (maximum of ∼ 30-35% apoptotic cells for 2 Gy carbon ions compared to ∼ 25% for X-rays) and chromosomal aberrations in the first cell-cycle after exposure (∼ 70% and ∼ 40% for 1 Gy of carbon ions and X-rays, respectively), with a higher fraction of non-transmissible aberrations. In contrast, for both radiation qualities the percentage of clones with chromosomal abnormalities was similar (40%). Using the frequency of colonies with clonal aberrations as a surrogate marker for the leukemia risk following radiotherapy of solid tumors, charged particle therapy is not expected to lead to an increased risk of leukemia in patients.

NF-κB-dependent DNA damage-signaling differentially regulates DNA double-strand break repair mechanisms in immature and mature human hematopoietic cells

Hematopoietic stem and progenitor cells (HSPC), that is, the cell population giving rise not only to all mature hematopoietic lineages but also the presumed target for leukemic transformation, can transmit (adverse) genetic events, such as are acquired from chemotherapy or ionizing radiation. Data on the repair of DNA double-strand-breaks (DSB) and its accuracy in HSPC are scarce, in part contradictory, and mostly obtained in murine models. We explored the activity, quality and molecular components of DSB repair in human HSPC as compared with mature peripheral blood lymphocytes (PBL). To consider chemotherapy/radiation-induced compensatory proliferation, we established cycling HSPC cultures. Comparison of pathway-specific repair activities using reporter systems revealed that HSPC were severely compromised in non-homologous end joining and homologous recombination but not microhomology-mediated end joining. We observed a more pronounced radiation-induced accumulation of nuclear 53BP1 in HSPC relative to PBL, despite evidence for comparable DSB formation from cytogenetic analysis and γH2AX signal quantification, supporting differential pathway usage. Functional screening excluded a major influence of phosphatidylinositol-3-OH-kinase (ATM/ATR/DNA-PK)- and p53-signaling as well as chromatin remodeling. We identified diminished NF-κB signaling as the molecular component underlying the observed differences between HSPC and PBL, limiting the expression of DSB repair genes and bearing the risk of an inaccurate repair.

p53 mutations associated with aging-related rise in cancer incidence rates

TP53’s role as guardian of the genome diminishes with age, as the probability of mutation increases. Previous studies have shown an association between p53 gene mutations and cancer. However, the role of somatic TP53 mutations in the steep rise in cancer rates with aging has not been investigated at a population level. This relationship was quantified using the International Agency for Research on Cancer (IARC) TP53 and GLOBOCAN cancer databases. The power function exponent of the cancer rate was calculated for 5-y age-standardized incidence or mortality rates for up to 25 cancer sites occurring in adults of median age 42 to 72 y. Linear regression analysis of the mean percentage of a cancer’s TP53 mutations and the corresponding cancer exponent was conducted for four populations: worldwide, Japan, Western Europe, and the United States. Significant associations (P ≤ 0.05) were found for incidence rates but not mortality rates. Regardless of the population studied, positive associations were found for all cancer sites, with more significant associations for solid tumors, excluding the outlier prostate cancer or sex-related tumors. Worldwide and Japanese populations yielded P values as low as 0.002 and 0.005, respectively. For the United States, a significant association was apparent only when analysis utilized the Surveillance, Epidemiology, and End Results (SEER) database. This study found that TP53 mutations accounts for approximately one-quarter and one-third of the aging-related rise in the worldwide and Japanese incidence of all cancers, respectively. These significant associations between TP53 mutations and the rapid rise in cancer incidence with aging, considered with previously published literature, support a causal role for TP53 according to the Bradford-Hill criteria. However, questions remain concerning the contribution of TP53 mutations to neoplastic development and the role of factors such as genetic instability, obesity, and gene deficiencies other than TP53 that reduce p53 activity.

Monte Carlo simulation of age-dependent radiation dose from alpha- and beta-emitting radionuclides to critical trabecular bone and bone marrow targets

Alpha (α) particles and low-energy beta (β) particles present minimal risk for external exposure. While these particles can induce leukemia and bone cancer due to internal exposure, they can also be beneficial for targeted radiation therapies. In this paper, a trabecular bone model is presented to investigate the radiation dose from bone- and marrow-seeking α and β emitters to different critical compartments (targets) of trabecular bone for different age groups. Two main issues are addressed with Monte Carlo simulations. The first is the absorption fractions (AFs) from bone and marrow to critical targets within the bone for different age groups. The other issue is the application of (223)Ra for the radiotherapy treatment of bone metastases. Both a static model and a simulated bone remodeling process are established for trabecular bone. The results show significantly lower AFs from radionuclide sources in the bone volume to the peripheral marrow and the haematopoietic marrow for adults than for newborns and children. The AFs from sources on the bone surface and in the bone marrow to peripheral marrow and haematopoietic marrow also varies for adults and children depending on the energy of the particles. Regarding the use of (223)Ra as a radionuclide for the radiotherapy of bone metastases, the simulations show a significantly higher dose from (223)Ra and its progeny in forming bone to the target compartment of bone metastases than that from two other more commonly used β-emitting radiopharmaceuticals, (153)Sm and (89)Sr. There is also a slightly lower dose from (223)Ra in forming bone to haematopoietic marrow than that from (153)Sm and (89)Sr. These results indicate a higher therapy efficiency and lower marrow toxicity from (223)Ra and its progeny. In conclusion, age-related changes in bone dimension and cellularity seem to significantly affect the internal dose from α and β emitters in the bone and marrow to critical targets, and (223)Ra may be a more efficient radiopharmaceutical for the treatment of bone metastases than (153)Sm and (89)Sr, if the diffusion of (219)Rn to the bone marrow is insignificant.

Promotional etiology for common childhood acute lymphoblastic leukemia: the infective lymphoid recovery hypothesis

This paper speculates on the role of infection in modifying a young child's risk of promoting precursor B-cell acute lymphoblastic leukemia (ALL). It is suggested that the heat shock instigated by infections, particularly in infancy, stimulates Th1 pro-inflammatory cytokines and an apoptosis-inhibitory environment. This infective stress also increases the number of cooperating oncogenic mutations in pre-leukemic cells, especially if the primary adaptive immune response is delayed. The glucocorticoid release that follows leads to acute thymic involution, a decline in antitumor immunity, and maturation arrest of B-lymphocytes. The infective lymphoid recovery hypothesis addresses an apparent contradiction-that a non-hygienic environment primes the adaptive immune response and is protective against childhood ALL, while multiple infections occurring later increase the risk of childhood ALL. In affluent (compared to less-affluent) societies, the characteristic ALL incidence peak in early childhood, and the shortened time to diagnosis, arise from surviving recurrent infections and the accumulated loss and recovery of lymphoid tissue. Evidence supporting the hypothesis, such as the role of lymphoid tissue reconstitution cytokines that stimulate proliferation stress on B-cell progenitors, comes from the study of children with congenital syndromes that are susceptible to leukemia.

Drosophila: a model for studying genetic and molecular aspects of haematopoiesis and associated leukaemias

Vertebrate haematopoietic stem cells (HSCs) give rise to a hierarchically organised set of progenitors for erythroid, myeloid, lymphoid and megakaryocyte lineages, and are responsible for lifelong maintenance of the blood system. Dysregulation of the haematopoietic differentiation programme is at the origin of numerous pathologies, including leukaemias. With the discoveries that many transcriptional regulators and signalling pathways controlling blood cell development are conserved between humans and Drosophila melanogaster, the fruit fly has become a good model for investigating the mechanisms underlying the generation of blood cell lineages and blood cell homeostasis. In this review article, we discuss how genetic and molecular studies of Drosophila haematopoiesis can contribute to our understanding of the haematopoietic niche, as well as of the origin and/or progression of haematopoietic malignancies in humans.