Opinion on the Optimal Histologic Evaluation of the Bone Marrow in Nonclinical Toxicity Studies

Identification of bone marrow toxicity is an important issue in drug development and toxicologic pathologists play a critical role in that identification. Knowledge of the general components of bone marrow, relevant anatomical and species differences, and the standard approach (routine systematic histological evaluation of the bone marrow in conjunction with analysis of the peripheral complete blood count data) will be reviewed. Specific morphologic features that anatomic pathologists should look for in the various components of bone marrow as well as suggested terminology for bone marrow findings will be discussed. Finally, an opinion on the limitations of the standard approach to bone marrow evaluation will be provided including general recommendations on when additional methods (image analysis of hematoxylin and eosin stained slides, flow cytometry or Sysmex XT 2000iV analysis, cytological evaluation of bone marrow smears, in vitro models, and transmission electron microscopy) might be useful in the detection or further characterization of bone marrow toxicity. [Box: see text]

Renal and Red Marrow Dosimetry in Peptide Receptor Radionuclide Therapy: 20 Years of History and Ahead

The development of dosimetry and studies in peptide receptor radionuclide therapy (PRRT) over the past two decades are reviewed. Differences in kidney and bone marrow toxicity reported between 90Y, 177Lu and external beam radiotherapy (EBRT) are discussed with regard to the physical properties of these beta emitter radionuclides. The impact of these properties on the response to small and large tumors is also considered. Capacities of the imaging modalities to assess the dosimetry to target tissues are evaluated. Studies published in the past two years that confirm a red marrow uptake in 177Lu-DOTATATE therapy, as already observed 20 years ago in 86Y-DOTATOC PET studies, are analyzed in light of the recent developments in the transferrin transport mechanism. The review enlightens the importance (i) of using state-of-the-art imaging modalities, (ii) of individualizing the activity to be injected with regard to the huge tissue uptake variability observed between patients, (iii) of challenging the currently used but inappropriate blood-based red marrow dosimetry and (iv) of considering individual tandem therapy. Last, a smart individually optimized tandem therapy taking benefit of the bi-orthogonal toxicity-response pattern of 177Lu-DOTATATE and of 90Y-DOTATOC is proposed.

Aspirin Protective Effect Against Cyclophosphamide Hematological Toxicity In Experimental Animals

Bone marrow toxicity is the most important factor limiting the use of cytotoxic drugs like alkylating agents in cancer treatment. Recently PG synthase enzyme inhibitors have been reported to potentiate the cytotoxic effects of these agents on cancer cells but little is known if they can affect the toxicity of these agents on bone marrow or other tissues. Cyclophosphamide is one of the most commonly used alkylating agent. In the present work, the effect of these PG synthase enzyme inhibitors, aspirin on cyclophosphamide myelotoxicity was determined employing the peripheral blood count to reflect bone marrow injury. The effect on body weight changes caused by cyclophosphamide was also determined. 1. Cyclophosphamide in doses of 25, 50 and 75 mg/kg i. v. produced as a dose dependent reduction in total WBC count, granulocyte, non granulocyte, and Hb% which was maximum on second day after injection and still present on 5th day post injection. It also produced a dose dependent reduction in body weight on day 5 after injection. 2. Aspirin in doges of 75, 150 and 300 mg/kg i. m. protected against the reduction in WBC counts 'measured for 5 days after injection of cyclophosphamide (50 mg/kg). This protection was not dose dependent, though it was more optimum with 300 mg/kg and disappeared largely when a dose of 450 mg/kg was used. Aspirin did not prevent the changes in Hb% but retard the reduction in body weight caused by cyclophosphamide. 3. It is concluded that aspirin can help to reduce injury and enhance recovery from bone marrow toxicity caused by cytotoxic agents such as the alkylating drugs cyclophosphamide for which no specific antidote is available. Aspirin produces this effect possibly by eliminating the harmful inhibitory effect of excess PGs or leukotrienes, released by bone marrow injury on growth factors of haemopoietic progenitor cells. The magnitude of this protection on WBC counts does not seem to differ between either PG synthase enzyme inhibitors or steroids when used alone or in combination although a synergistic effect in protecting erythropoiesis is observed.

Possible Protective Effects of Lutein against Ciprofloxacin Induced Bone Marrow Toxicity in Rats

Ciprofloxacin, which is a second generation of fluoroquinolone and one of the most effective and widely used drugs within fluoroquinolone. Unfamiliar adverse effects of ciprofloxacin such as bone marrow (BM) suppression, thrombocytopenia, anemia, agranulocytosis, renal failure, and others observed. Lutein, is a xanthophyll (an oxygenated carotenoid), was focused by most studies as it has a strong antioxidant activity in vitro; and also, it has been associated with reducing the risk of the age-related disorders. The current study was designed to describe the role of apoptosis through the measurement of Bcl-2 associated X protein (Bax) marker, as mechanisms of bone marrow toxicity induced by ciprofloxacin and to find whether lutein may have protective effects on ciprofloxacin-induced toxicity in bone marrow of rats. Ciprofloxacin (Group II) caused significant (P<0.05) reduction in total RBCs counts and -WBCs, and significantly elevations (P<0.05) Bcl-2 associated X protein (Bax) in bone marrow (BM) tissues homogenates compared to control (Group I) rats.

In vitro anti-Toxoplasma gondii efficacy of synthesised benzyltriazole derivatives

Toxoplasma gondii, an obligate intracellular parasite, is the aetiological agent of toxoplasmosis, a disease that affects approximately 25% – 30% of the world’s population. At present, no safe and effective vaccine exists for the prevention of toxoplasmosis. Current treatment options for toxoplasmosis are active only against tachyzoites and may also cause bone marrow toxicity. To contribute to the global search for novel agents for the treatment of toxoplasmosis, we herein report the in vitro activities of previously synthesised benzyltriazole derivatives. The effects of these compounds against T. gondii in vitro were evaluated by using a expressing green fluorescent protein (GFP) type I strain parasite (RH-GFP) and a type II cyst-forming strain of parasite (PruΔku80Δhxgprt). The frontline antitubercular drug isoniazid, designated as Frans J. Smit -isoniazid (FJS-INH), was also included in the screening as a preliminary test in view of future repurposing of this agent. Of the compounds screened, FJS-302, FJS-303, FJS-403 and FJS-INH demonstrated 80% parasite growth inhibition with IC50 values of 5.6 µg/mL, 6.8 µg/µL, 7.0 µg/mL and 19.8 µg/mL, respectively. FJS-302, FJS-303 and FJS-403 inhibited parasite invasion and replication, whereas, sulphadiazine (SFZ), the positive control, was only effective against parasite replication. In addition, SFZ induced bradyzoite differentiation in vitro, whilst FJS-302, FJS-303 and FJS-403 did not increase the bradyzoite number. These results indicate that FJS-302, FJS-303 and FJS-403 have the potential to act as a viable source of antiparasitic therapeutic agents.

Ultrasound-Triggered Release of 5-Fluorouracil from Soy Lecithin Echogenic Liposomes

Colorectal cancer is the third most diagnosed cancer and the second leading cause of death. The use of 5-fluorouracil (5-FU) has been the major chemotherapeutic treatment for colorectal cancer patients. However, the efficacy of 5-FU is limited by drug resistance, and bone marrow toxicity through high-level expression of thymidylate synthase, justifying the need for improvement of the therapeutic index. In this study, the effects of ultrasound on echogenic 5-FU encapsulated crude soy liposomes were investigated for their potential to address these challenges. Liposomes were prepared by thin-film hydration using crude soy lecithin and cholesterol. Argon gas was entrapped in the liposomes for sonosensitivity (that is, responsiveness to ultrasound). The nanoparticles were characterized for particle size and morphology. The physicochemical properties were also evaluated using differential scanning calorimetry, Fourier transform infrared and X-ray diffraction. The release profile of 5-FU was assessed with and without 20 kHz low-frequency ultrasound waves at various amplitudes and exposure times. The result reveal that 5-FU-loaded liposomes were spherical with an encapsulation efficiency of approximately 60%. Approximately 65% of 5-FU was released at the highest amplitude and exposure time was investigated. The results are encouraging for the stimulated and controlled release of 5-FU for the management of colorectal cancer.

Renal and Red Marrow Dosimetry in Peptide Receptor Radionuclide Therapy: 20 Years of History and Ahead

The development of dosimetry and studies in peptide receptor radionuclide therapy (PRRT) over these two last decades are reviewed. Differences in kidney and bone marrow toxicity reported between 90Y, 177Lu and external beam radiotherapy (EBRT) are discussed with regards to the physical properties of these beta emitter radionuclides. The impact of these properties on the response to small and large tumors is also considered. Capacities of the imaging modalities to assess the dosimetry to target tissues are evaluated. Studies published in the last two years that confirm a red marrow uptake in 177Lu-DOTATATE therapy, as already observed 20 years ago in 86Y-DOTATOC PET studies, are commented and analyzed in the light of the recent knowledges in transferrin transport mechanism. The review enlightens the importance i) of using state of the art imaging modalities, ii) of individualizing the activity to be injected with regards to the huge tissue uptake variability observed between patients, iii) of challenging the currently used but inappropriate blood based red marrow dosimetry and iv) of considering individually tandem therapy. Last, a smart individually optimized tandem therapy taking benefit of the bi-orthogonal toxicity-response pattern of 177Lu-DOTATATE and of 90Y-DOTATOC is proposed.

Protective Effects of Spirulina against Cyclophosphamide Induced Bone Marrow Toxicity in Mice

Spirulina Platenesis (Sp) is rich in important compounds with antioxidant effects. This study investigates the treatment and prophylactic effect of Spirulina Platenesis (Sp) against Cyclophosphamide (CP) induced bone marrow toxicity. Fifty female BALB/C mice were randomly classified into 5 equal groups: (1) Normal controls; (2) CP group: injected with 40 mg/kg for 10 days; (3) Sp group: supplied by Sp (1000 mg/kg) for 10 days; (4) Treatment group: CP + Sp; (5) Prophylactic group: Sp + CP. After 10 days, At the end of the study period, all rats were killed, blood was withdrawn, and bone marrow (BM) was subjected to investigation. Cyclophosphamide administration caused rapid dimension in CBC parameter, Bone marrow WBC count and Erythropiotein concentration in blood that have been recovered with Sp administration. According to histological analysis of the bone marrow, spirulina impaired the proliferation and hypercellularity of immature myeloid elements in the bone marrow, which CP decreased. Obviously, spirulina may with antioxidative activity reduced the oxidative stress and toxicity induced by cyclophosphamide in mouse bone marrow cells.

Antioxidant and hepatoprotective property of squalene for counteracting the oxidative damage induced by methotrex- ate in experimental rats

Methotrexate (MTX), an antifolate drug, is extensively prescribed for patients suffering from diseases like cancer, psoriasis, neoplasms, and rheumatoid arthritis. Despite its effectiveness, MTX sometimes finds limited application because its undesirable side effects, including hepatic or renal impairment, bone marrow toxicity and gastrointestinal mucosal injury. Squalene, a highly unsaturated isoprenoid compound, isolated from shark liver oil has great potential in neutralizing the damaging effects triggered by free radicals. Therefore, in this study, the protective role of dietary squalene supplementation on oxidative stress induced by methotrexate in experimental rats was evaluated. A significant reduction was displayed in the activities of catalase (CAT) and superoxide dismutase (SOD) in MTX-intoxicated groups compared to other groups. Similarly, the activities of glutathione dependant enzymes (GPx and GST) and reduced glutathione (GSH) in MTX-induced groups were shown to be lower compared to the untreated control. Increased LPO (lipid peroxide) level was found in MTX-intoxicated groups compared to other groups. In addition, alterations in the levels of liver marker enzymes like AST, ALP, ALT, and LDH were noticed in MTX intoxicated groups compared to other groups. Biochemical results were confirmed by the histopathological examination of liver sections. In conclusion, the result obtained in the present study proposes that squalene exerts antioxidant activity and is capable of ameliorating oxidative stress and liver injury induced by MTX.