Effects of KRN633, an Inhibitor of Vascular Endothelial Growth Factor Receptor-2 Tyrosine Kinase, on Vascular Development of Placenta and Fetus of Mid Pregnancy in Mice

Coupling between macrophage phenotype, angiogenesis and bone formation by calcium phosphates

The ability of calcium phosphate (CaP) materials to induce bone formation varies with their physicochemical properties, with surface topography as one of the most crucial triggers. In view of the natural wound healing processes (e.g., inflammation, angiogenesis, tissue formation and remodeling) initiated after surgical implantation, we here comparatively investigated the biological cascades occurring upon ectopic implantation of a tricalcium phosphate with submicron surface topography (TCP-S, osteoinductive) and a tricalcium phosphate with micron-scale topography (TCP-B, non-osteoinductive). In vitro, TCP-S facilitated M2 polarization of macrophages derived from a human leukemic cell line (THP-1) as shown by the enhanced secretion of TGF-β and CCL18. Interestingly, the conditioned media of polarized M2 macrophages on TCP-S enhanced tube formation by human umbilical vein endothelial cells (HUVECs), while had no influence on the osteogenic differentiation of human bone marrow stromal cells (HBMSCs). Following an intramuscular implantation in canines, TCP-S locally increased typical M2 macrophage markers (e.g., IL-10) at week 1 to 3 and enhanced blood vessel formation after week 3 as compared to TCP-B. Bone formation was observed histologically in TCP-S 6 weeks after implantation, and bone formation was inhibited when an angiogenesis inhibitor (KRN633) was loaded onto TCP-S. No bone formation was observed for TCP-B. The data presented herein suggest strong links between macrophage polarization, angiogenesis and CaP-induced bone formation. STATEMENT OF SIGNIFICANCE: The ability of calcium phosphate (CaP) materials to induce bone formation varies with their physicochemical properties, and the key physicochemical properties relevant to CaP-induced bone formation have been outlined in the last two decades. However, the biological mechanism underlying this material-driven osteoinduction remains largely unknown. This manuscript presented demonstrates strong links between surface topography, macrophage polarization, angiogenesis and bone formation in CaP materials implanted in non-osseous sites. The finding may provide new clues for further exploring the possible mechanism underlying osteoinduction by CaP materials.

Anticancer drugs during pregnancy

Although cancer diagnoses during pregnancy are rare, they have been increasing with the rise in maternal age and are now a topic of international concern. In some cases, the administration of chemotherapy is unavoidable, though there is a relative paucity of evidence regarding the administration of anticancer drugs during pregnancy. As more cases have gradually accumulated and further research has been conducted, we are beginning to elucidate the appropriate timing for the administration of chemotherapy, the regimens that can be administered with relative safety, various drug options and the effects of these drugs on both the mother and fetus. However, new challenges have arisen, such as the effects of novel anticancer drugs and the desire to bear children during chemotherapy. In this review, we outline the effects of administering cytotoxic anticancer drugs and molecular targeted drugs to pregnant women on both the mother and fetus, as well as the issues regarding patients who desire to bear children while being treated with anticancer drugs.

Structural and functional changes in retinal vasculature induced by retinal ischemia-reperfusion in rats

Recent studies have shown retinal blood vessel damage in experimental models of retinal degeneration. The present study aimed to provide a detailed description of the structural and functional changes in retinal vasculature induced by retinal ischemia-reperfusion (I/R) in rats. Retinal ischemia was induced for 60 min by raising the intraocular pressure to 130 mmHg. Morphological changes in vascular components (endothelial cells, pericytes, and basement membranes), the patency and perfusion of blood vessels, and expression of vascular endothelial growth factor (VEGF) were assessed in the retinas at 2, 7, and 14 days after I/R. Significant reductions in vascular densities were observed at 7 and 14 days after I/R. Pericyte loss occurred after the appearance of endothelial cell degeneration, whereas the vascular basement membranes remained unchanged. Some vessels showed no perfusion in damaged retina. A decrease in the immunoreactivity of VEGF in the region extending from the ganglion cell layer to the outer plexiform layer was evident 2 days after I/R. In retinal I/R model, retinal ganglion cells are rapidly (<2 day) damaged following reperfusion, therefore, the current results suggest that neuronal cell damage precedes capillary degeneration, and neuronal cells may play an important role in maintaining vascular structure and function through the production and release of endothelial cell survival factors, including VEGF. Neuronal cell damage could be an additional cause of progression of ischemic retinal damage by reducing blood supply to the retinal neurons due to the destruction of the blood vessel network.

KRN633, an inhibitor of vascular endothelial growth factor receptor tyrosine kinase, induces intrauterine growth restriction in mice

We previously reported that treatment with KRN633, a vascular endothelial growth factor receptor tyrosine kinase inhibitor, during mid-pregnancy caused intrauterine growth restriction resulting from impairment of blood vessel growth in the labyrinthine zone of the placenta and fetal organs. However, the relative sensitivities of blood vessels in the placenta and fetal organs to vascular endothelial growth factor (VEGF) inhibitors have not been determined. In this study, we aimed to examine the effects of KRN633 on the vasculatures of organs in mother mice and their newborn pups by immunohistochemical analysis. Pregnant mice were treated daily with KRN633 (5 mg/kg) either from embryonic day 13.5 (E13.5) to E17.5 or from E13.5 to the day of delivery. The weights of the pups of KRN633-treated mice were lower than those of the pups of vehicle-treated mothers. However, no significant difference in body weight was observed between the vehicle- and KRN633-treated mice. The vascular development in the organs (the pancreas, kidney, and intestine) and intestinal lymphatic formation of the pups of KRN633-treated mothers was markedly impaired. In contrast, the KRN633 treatment showed no significant effect on the vascular beds in the organs, including the labyrinthine zone of the placenta, of the mother mice. These results suggest that blood vessels in fetal organs are likely to be more sensitive to reduced VEGF signaling than those in the mother. A partial loss of VEGF function during pregnancy could suppress vascular growth in the fetus without affecting the vasculature in the mother mouse, thereby increasing the risk of intrauterine growth restriction.

Role of vascular endothelial growth factor in maintenance of pregnancy in mice

It is well known that withdrawal of progesterone from the maternal circulation is a critical stimulus to parturition in rodents, such as rats and mice. However, mechanisms that determine the timing of progesterone withdrawal are not completely understood. In the present study, we examined whether the vascular endothelial growth factor (VEGF) system in the corpus luteum (CL) contributes to the regulation of circulating progesterone levels and acts as a determinant of the timing of parturition in mice. We found that reduction in the expression levels of VEGF and VEGF receptor-2 in the CL precedes the impairment of luteal circulation and a series of events leading to parturition (i.e., reduction of plasma progesterone, enhancement of myometrium contractility, and onset of parturition). Blocking of VEGF signaling by using the inhibitor of VEGFR tyrosine kinase KRN633 at mid-pregnancy caused a similar sequence of events and induced preterm birth. These results suggest that the VEGF system in the CL plays a critical role in maintaining a high level of circulating progesterone, and determining the timing of parturition in mice.

Health during pregnancy and beyond: Fetal trophoblast cells as chief co-ordinators of intrauterine growth and reproductive success

Abstract Differentiation of extra-embryonic tissues and organs, notably the placenta, is vital for embryonic development and growth throughout gestation, starting from a few days after fertilization when the trophoblast cell lineage arises until parturition. In utero metabolic programming events may even extend the impact of placental function well into adulthood as they may predispose the offspring to common pathologies such as diabetes and cardiovascular disease. This review summarizes key steps that lead up to formation of a functional placenta. It highlights recent insights that have advanced our view of how early trophoblast expansion is achieved and how sufficient maternal blood supply to the developing fetus is secured. Exciting cumulative data have revealed the importance of a close cross-talk between the embryo proper and extra-embryonic trophoblast cells that involves extracellular matrix components in the establishment of a stem cell-like niche and proliferation compartment. Remarkably, placental function also relies on beneficial interactions between trophoblast cells and maternal immune cells at the implantation site. Our growing knowledge of the molecular mechanisms involved in trophoblast differentiation and function will help to devise informed approaches aimed at deciphering how placentation is controlled in humans as an essential process for reproductive success and long-term health.

Infection of specific strains of Streptococcus mutans, oral bacteria, confers a risk of ulcerative colitis

Although oral bacteria-associated systemic diseases have been reported, association between Streptococcus mutans, pathogen of dental caries, and ulcerative colitis (UC) has not been reported. We investigated the effect of various S. mutans strains on dextran sodium sulfate (DSS)-induced mouse colitis. Administration of TW295, the specific strain of S. mutans, caused aggravation of colitis; the standard strain, MT8148 did not. Localization of TW295 in hepatocytes in liver was observed. Increased expression of interferon-γ in liver was also noted, indicating that the liver is target organ for the specific strain of S. mutans-mediated aggravation of colitis. The detection frequency of the specific strains in UC patients was significantly higher than in healthy subjects. Administration of the specific strains of S. mutans isolated from patients caused aggravation of colitis. Infection with highly-virulent specific types of S. mutans might be a potential risk factor in the aggravation of UC.