Anna Efthimiadou

Human leptin induces angiogenesis in vivo

Leptin is an adipocyte-produced peptide, which plays a crucial role in the regulation of body weight. There is also evidence that leptin stimulates endothelial cell proliferation and the formation of capillary-like tubes in vitro. The disc angiogenesis system was used to measure the angiogenic effect of leptin in vivo. Discs containing 25, 50, 100 and 250ng/ml of leptin were implanted subcutaneously in Wistar rats, removed after a growth period of 7 and 14 days, and compared with spontaneous growth controls and with positive controls containing equivalent doses of vascular endothelial growth factor (VEGF). Discs were examined morphologically for stroma and vessel development and by immunohistochemistry for quantitative evaluation of angiogenesis. The specificity of the angiogenic effect of leptin was tested by blocking leptin with a polyclonal anti-leptin antibody. Leptin induced a significant level of angiogenesis in a dose-dependent manner both at 7 and 14 days, with a peak at the dose of 100ng/ml. The angiogenic activity of leptin was completely abolished by the anti-leptin neutralizing antibody. VEGF also induced significant dose-dependent angiogenesis at the same time points with a peak observed at a concentration of 100ng/ml. The angiogenic response to leptin was significantly higher at 7 days compared with VEGF but not at the 14-day time point. In conclusion, leptin has a specific angiogenic effect in vivo, which is dose- and time-dependent in a concentration range of 25-250ng/ml. This effect is equivalent to the angiogenic effect of VEGF but is evident earlier compared with VEGF.

Angiogenic effect of intramuscular administration of basic and acidic fibroblast growth factor on skeletal muscles and influence of exercise on muscle angiogenesis

Background: Angiogenic factors which control the angiogenic process represent a promising strategy for restoration of blood flow, but require further evaluation before clinical use. Exercise has also been reported to induce neovascularisation in muscles. Objectives: To evaluate the angiogenic effects of basic fibroblast growth factor (b-FGF) and acidic fibroblast growth factor (a-FGF) on rat gastrocnemius muscle, when administered intramuscularly, and to compare them with those obtained by daily exercise. Methods: Forty nine rats were allotted to the following groups: A, controls; B, exercise by swimming; C1 and C2, intramuscular injection of b-FGF and a-FGF respectively; D1 and D2, b-FGF and a-FGF injection in combination with exercise. The antibody mouse anti-rat CD31 was used to evaluate the numbers of blood vessels present in histological preparations of gastrocnemius muscle. Results: Significant increases in the numbers of blood vessels of the right gastrocnemius muscles in groups C1 and D1 were observed compared with controls (p<0.05). There was only a slight increase in angiogenesis in the left gastrocnemius muscle of groups C1 and D1 compared with controls (p>0.05), and there was a decrease in angiogenesis in the gastrocnemius muscle of the swimming group compared with controls. Conclusion: The intramuscular administration of b-FGF, but not a-FGF, induced significant local angiogenesis in gastrocnemius muscle at the site of injection.

ERYTHROPOIETIN ENHANCES ANGIOGENESIS IN AN EXPERIMENTAL CYCLOSPORINE A‐INDUCED NEPHROTOXICITY MODEL IN THE RAT

1 Erythropoietin (EPO) is a hormone regulating the proliferation and differentiation of erythroid precursor cells. The hypothesis that haematopoietic and endothelial cells share a common haemanglioblast progenitor among others is based on the finding that both cell lineages express cell surface antigens, such as CD31 and CD34. 2 In the present study, we investigated the angiogenic potential of recombinant human erythropoietin on cyclosporine A (CsA)‐induced nephrotoxicity in the rat kidney and compared it with the effect of basic fibroblast growth factor (bFGF), a well‐known angiogenic factor. 3 Rats were divided into five groups: A (control), B (EPO treated), C (CsA treated), D (CsA + EPO treated) and E (CsA + bFGF treated). Mouse anti‐human CD31 and CD34 antibodies were used to evaluate the kidney vessels present in histological preparations. 4 Glomerular and peritubular capillaries in Group B (EPO) were increased compared with the control (Group A; P < 0.05). Reduction of the same kidney vessels (glomerular and peritubular capillaries) in Group C (CsA; P < 0.05) compared with controls was observed, whereas in Groups D (CsA + EPO treated) and E (CsA + bFGF treated), capillaries were increased compared with Group C (CsA; P < 0.05). 5 Erythropoietin has a significant angiogenic effect in rat kidney with CsA‐induced nephrotoxicity, similar to the effect of the other angiogenic factor bFGF.

The angiogenetic effect of intramuscular administration of b-FGF and a-FGF on cardiac muscle: The influence of exercise on muscle angiogenesis

Abstract Although angiogenetic therapy using recombinant growth factors holds much hope for the treatment of ischaemic diseases, there are still many unanswered questions, including the method of administration, the correct dose of these factors, and the duration of the therapeutic approach. Exercise has also been suggested to induce neovascularizaiton in muscles. We evaluated the angiogenetic effects of the intramuscular administration of basic-fibroblast growth factor (b-FGF) and acidic-fibroblast growth factor (a-FGF) in rat heart, compared with rats who exercised daily. In conclusion, both the intramuscular administration of b-FGF and exercise increased significantly angiogenesis in the heart in contrast to the intramuscular administration of a-FGF, which was ineffective.

Angiogenic effect of intramuscular administration of basic fibroblast growth factor in atrophied muscles: an experimental study in the rat

Background: Although angiogenic therapy using recombinant growth factors holds much hope for the treatment of ischaemic diseases, there are still many unanswered questions, including its effectiveness on atrophic muscles. Objective: To evaluate the angiogenic effects of intramuscularly administered basic fibroblast growth factor (b-FGF) on normal gastrocnemius muscles of rats and atrophic gastrocnemius muscles after tenotomy. Methods: Forty rats were divided into groups as follows: group A, controls; group B, injected with 1 μg b-FGF; group C, tenotomy performed on the right gastrocnemius muscle; group D, tenotomy and 1 μg b-FGF. Mouse anti-rat CD31 antibody was used to evaluate the number of blood vessels present in histological preparations. Results: There was a significant (p<0.01) decrease in the number of blood vessels compared with the controls in the atrophic muscles of group C. This was similar to the decrease in muscle weight in this group. However, there was a significant (p<0.01) increase in the number of blood vessels compared with the controls in groups B and D. Similarly, there was a significant (p<0.01) increase in the number of blood vessels in group D compared with the atrophic muscles in group C. Conclusion: Intramuscular administration of b-FGF increases angiogenesis in both normal and atrophic rat gastrocnemius muscles at the injection area.

Unremitting early stage Hodgkin disease: report of 7 cases and bone marrow tissue immunohistochemical marker study

Bone marrow is infrequently implicated in early stages of Hodgkin’s disease. We studied the immunohistochemical bone marrow tissue of 7 out of 20 cases with early stage Hodgkin’s disease of the mixed cellularity variant, diagnosed by lymph node biopsy at initial presentation, not responding to radiotherapy alone, in order to examine possible marrow attack. A statistically significant prevalence of CD45, CD45RO, and CD4 positive infiltrates, to the advantage of unremitting hosts, was found. The predominance of CD4-positive cells in the bone marrow space might be suggestive of involvement in the process and could explain the abnormal cytokine production leading to reduced T-cell immunity and inefficient antitumor response despite the existence of a vast majority of reactive infiltrating immune cells. Acta Medica Iranica, 44(3): 208-212; 2006