Troponin I is present in human cartilage and inhibits angiogenesis

A multi-omics approach for understanding blood digestion dynamics in Ixodes scapularis and identification of anti-tick vaccine targets

Ixodes scapularis, the black-legged tick, is a major arthropod vector that transmits the causative agents of Lyme disease and several other pathogens of human significance. The tick midgut is the main tissue involved in blood acquisition and digestion and the first organ to have contact with pathogens ingested through the blood meal. Gene expression in the midgut before, during, and after a blood meal may vary in response to the physiological changes due to blood feeding. A systems biology approach based on RNA and protein sequencing was used to gain insight into the changes in tick midgut transcripts and proteins during blood ingestion (unfed and partially fed) and digestion (1-, 2-, 7-, and 14 days post detachment from the host) by the Ixodes scapularis female ticks. A total of 2,726 differentially expressed transcripts, and 449 proteins were identified across the time points. Genes involved in detoxification of xenobiotics, proteases, protease inhibitors, metabolism, and immunity were differentially expressed in response to blood feeding. Similarly, proteins corresponding to the same groups were also differentially expressed. Nine genes from major gene categories were chosen as potential vaccine candidates, and, using RNA interference, the effect of these gene knockdowns on tick biology was investigated. Knockdown of these genes had variable negative impacts on tick physiology, such as the inability to engorge fully and to produce eggs and increased mortality. These and additional gene targets provide opportunities to explore novel tick control strategies.

Genome-wide survey identifies TNNI2 as a target of KLF7 that inhibits chicken adipogenesis via downregulating FABP4

Krüppel-like factor 7 (KLF7) negatively regulates adipocyte differentiation; however, the mechanism underlying its activity in mammals and birds remains poorly understood. To identify genome-wide KLF7-binding motifs in preadipocytes, we conducted a chromatin immunoprecipitation-sequencing analysis of immortalized chicken preadipocytes (ICP2), which revealed 11,063 specific binding sites. Intergenic binding site analysis showed that KLF7 regulates several novel factors whose functions in chicken and mammal adipogenesis are underexplored. We identified a novel regulator, troponin I2 (TNNI2), which is positively regulated by KLF7. TNNI2 is downregulated during preadipocyte differentiation and acts as an adipogenic repressor at least in part by repressing FABP4 promoter activity. In conclusion, we demonstrated that KLF7 functions through cis-regulation of TNNI2, which inhibits adipogenesis. Our findings not only provide the first genome-wide picture of KLF7 associations in preadipocytes but also identify a novel function of TNNI2.

The essential anti-angiogenic strategies in cartilage engineering and osteoarthritic cartilage repair

In the cartilage matrix, complex interactions occur between angiogenic and anti-angiogenic components, growth factors, and environmental stressors to maintain a proper cartilage phenotype that allows for effective load bearing and force distribution. However, as seen in both degenerative disease and tissue engineering, cartilage can lose its vascular resistance. This vascularization then leads to matrix breakdown, chondrocyte apoptosis, and ossification. Research has shown that articular cartilage inflammation leads to compromised joint function and decreased clinical potential for regeneration. Unfortunately, few articles comprehensively summarize what we have learned from previous investigations. In this review, we summarize our current understanding of the factors that stabilize chondrocytes to prevent terminal differentiation and applications of these factors to rescue the cartilage phenotype during cartilage engineering and osteoarthritis treatment. Inhibiting vascularization will allow for enhanced phenotypic stability so that we are able to develop more stable implants for cartilage repair and regeneration.

Troponin Variants in Congenital Myopathies: How They Affect Skeletal Muscle Mechanics

The troponin complex is a key regulator of muscle contraction. Multiple variants in skeletal troponin encoding genes result in congenital myopathies. TNNC2 has been implicated in a novel congenital myopathy, TNNI2 and TNNT3 in distal arthrogryposis (DA), and TNNT1 and TNNT3 in nemaline myopathy (NEM). Variants in skeletal troponin encoding genes compromise sarcomere function, e.g., by altering the Ca²⁺ sensitivity of force or by inducing atrophy. Several potential therapeutic strategies are available to counter the effects of variants, such as troponin activators, introduction of wild-type protein through AAV gene therapy, and myosin modulation to improve muscle contraction. The mechanisms underlying the pathophysiological effects of the variants in skeletal troponin encoding genes are incompletely understood. Furthermore, limited knowledge is available on the structure of skeletal troponin. This review focusses on the physiology of slow and fast skeletal troponin and the pathophysiology of reported variants in skeletal troponin encoding genes. A better understanding of the pathophysiological effects of these variants, together with enhanced knowledge regarding the structure of slow and fast skeletal troponin, will direct the development of treatment strategies.

Subchondral bone microenvironment in osteoarthritis and pain

Osteoarthritis comprises several joint disorders characterized by articular cartilage degeneration and persistent pain, causing disability and economic burden. The incidence of osteoarthritis is rapidly increasing worldwide due to aging and obesity trends. Basic and clinical research on osteoarthritis has been carried out for decades, but many questions remain unanswered. The exact role of subchondral bone during the initiation and progression osteoarthritis remains unclear. Accumulating evidence shows that subchondral bone lesions, including bone marrow edema and angiogenesis, develop earlier than cartilage degeneration. Clinical interventions targeting subchondral bone have shown therapeutic potential, while others targeting cartilage have yielded disappointing results. Abnormal subchondral bone remodeling, angiogenesis and sensory nerve innervation contribute directly or indirectly to cartilage destruction and pain. This review is about bone-cartilage crosstalk, the subchondral microenvironment and the critical role of both in osteoarthritis progression. It also provides an update on the pathogenesis of and interventions for osteoarthritis and future research targeting subchondral bone.

Characterization of TNNC1 as a Novel Tumor Suppressor of Lung Adenocarcinoma

In this study, we describe a novel function of TNNC1 (Troponin C1, Slow Skeletal and Cardiac Type), a component of actin-bound troponin, as a tumor suppressor of lung adenocarcinoma (LUAD). First, the expression of TNNC1 was strongly down-regulated in cancer tissues compared to matched normal lung tissues, and down-regulation of TNNC1 was shown to be strongly correlated with increased mortality among LUAD patients. Interestingly, TNNC1 expression was enhanced by suppression of KRAS, and ectopic expression of TNNC1 in turn inhibited KRASG12D-mediated anchorage independent growth of NIH3T3 cells. Consistently, activation of KRAS pathway in LUAD patients was shown to be strongly correlated with down-regulation of TNNC1. In addition, ectopic expression of TNNC1 inhibited colony formation of multiple LUAD cell lines and induced DNA damage, cell cycle arrest and ultimately apoptosis. We further examined potential correlations between expression levels of TNNC1 and various clinical parameters and found that low-level expression is significantly associated with invasiveness of the tumor. Indeed, RNA interference-mediated down-regulation of TNNC1 led to significant enhancement of invasiveness in vitro. Collectively, our data indicate that TNNC1 has a novel function as a tumor suppressor and is targeted for down-regulation by KRAS pathway during the carcinogenesis of LUAD.

Molecular characterization of troponin C (TnC) in Scylla paramamosain and its role in white spot syndrome virus and Vibrio alginolyticus infection

Troponin C (TnC) is one member of the EF-hand superfamily. In many species, this gene had been identified and related functions had been elucidated. The TnC gene was still blank in the Scylla paramamosain. We obtained the TnC gene for the first time in the S. paramamosain. And we systematically analyzed the possible role of this gene in the innate immunity of S. paramamosain while infected with white spot syndrome virus (WSSV) or Vibrio alginolyticus. The full-length 1427 bp sequence of TnC contains a 453 bp open reading frame (ORF) for encoding a 151 amino acid protein. Detection of tissue specificity of gene expression showed that the TnC was primarily expressed in muscle tissue. The expression of TnC was successfully inhibited by RNA interference technology, and several immune genes were affected. The activity of phenoloxidase and superoxide dismutase increased, and the total hemocytes counts increased after RNAi of TnC. It was found that after infection with V. alginolyticus and WSSV, the expression of TnC in hemocytes decreased. Infected with V. alginolyticus and WSSV, the cumulative mortality and apoptotic rate of hemocytes increased after silencing the TnC gene. Our results indicate that TnC takes participate in the innate immunity of S. paramamosain and may plays a different role in the antiviral and antibacterial immune response.

High-sensitive cardiac troponin T as a marker of hemorrhagic complications in elderly patients anticoagulated for non-massive pulmonary embolism

BACKGROUND

Recent data have raised concerns about the risk/benefit ratio of thrombolysis in non-high risk pulmonary embolism patients due to increased serious bleeding events. Whether cardiac biomarkers could be of help for bleeding risk stratification in this setting remains elusive.

OBJECTIVES

To determine the prognostic accuracy of hs-cTnT, NT-proBNP, RIETE and PESI score for the occurrence of clinically relevant bleeding (CRB) in elderly patients under conventional anticoagulation therapy for non-massive pulmonary embolism (NMPE).

METHODS

We evaluated 230 elderly patients with available blood sample taken within one day from diagnosis. The primary study endpoint was CRB at 1, 3 and 24 months. Prognostic accuracies and associations were determined using C-statistics and subhazard ratios (SHR), respectively.

RESULTS

hs-cTnT displayed the highest discriminatory power at 1 month (C-statistics: 0.77, 95% CI: 0.68-0.88) which remained stable over time. Although C-statistics comparison indicated that hs-cTnT was not statistically superior to RIETE score (0.77 vs 0.67, p = 0.11), adding hs-cTnT to RIETE score significantly improved the C-statistics from 0.67 to 0.78 (p = 0.02). SHRs indicated that for each hs-cTnT log-unit increase, there was a 58% increase in the risk of CRB independently of the RIETE score (adjusted SHR: 1.58, 95% CI: 1.31-1.92). At the pre-specified cut-off of 14 ng/l, the negative predictive value of hs-cTnT was 96.9% (95% CI: 91.4-99.0) and 94.9 (95%CI: 88.6-97.8) at 1 and 3 months, respectively.

CONCLUSION

In elderly, hs-cTnT provides incremental prognostic information over the RIETE score and could represent a valuable tool to identify NMPE patients at low risk of bleeding.

The Troponin-I fast skeletal muscle is reliable marker for the determination of vitality in the suicide hanging

Troponin I (TnI) is the inhibitory subunit of the troponin complex in the sarcomeric thin filament of striated muscle and plays a central role in the calcium regulation of contraction and relaxation. Vertebrate TnI has evolved into three isoforms encoded by three homologous genes: TNNI1 for slow skeletal muscle TnI, TNNI2 for fast skeletal muscle TnI and TNNI3 for cardiac TnI, which are expressed under muscle type-specific and developmental regulations in both the atrium and ventricle of the heart. Skeletal muscle TnI (both sTnI iso-forms) have been proposed as a sensitive and fast fiber-specific serum marker of skeletal muscle damage; fsTnI concentration in increased peripheral blood when fast twitch fibers were damaged. In our study we investigate if the 'Troponin I, fast skeletal muscle' can also be used as a reliable diagnostic tool in forensic practice, to perform differential diagnosis about vitality in suicide by hanging and simulated hanging (suspension of the victim after murder). We selected 8 women and 13 men, mean age 52.2 years, who died from suicidal hanging. The ligature material used for hanging was soft material in 11 cases and hard material in 10 cases. We chose cases as a control group of adults (n = 10; six women, four men, mean age 47.3 years) that died from opioid overdose (n = 2), car accident (n = 3) and sudden cardiac death (n = 5). Those deaths were characterized by their rapidity. To test the Anti-Troponin I fast skeletal muscle Antibody (Abcam clone-134,838), we used a case of a subject who died of myocardial infarction (timing infarct dated to 24-36 h prior to death). The reactions to Troponin I (namely the amount and extent of marker depletion) was scored for each section from 0 to -3: 0 = no loss of staining; -1 = minimal decrease in staining, compared to normally stained tissue; -2 = clear decrease in staining with some positivity (brown color) remaining; and -3 = no positive (brown) staining. The set of results obtained leads us to believe that the use of this antibody (Anti-Troponin I fast skeletal muscle antibody) is very promising to be able to make a certain differential diagnosis between antemortem and postmortem hangings. It should be emphasized that the present study seems to open new and promising horizons in the possibility to discriminate between suicidal hanging and simulated hanging (suspension of the victim after murder).

Subchondral bone remodelling in osteoarthritis

Subchondral bone remodelling is an integral part of osteoarthritis and involves the development of subchondral sclerosis seen on plain imaging, along with osteophyte formation.

The development of these changes is due to persistent abnormal mechanical stresses which create a cellular and biomolecular response to microfractures in the subchondral bone and osteochondral junction.

An early sign is bone marrow lesions seen on MRI scanning. Healing can occur at this stage by correcting the abnormal loads. Persistence leads to what is thought to be a delayed union or nonunion response by the bone.

Microfractures of the osteochondral junction, coupled with articular cartilage fissuring and loss, allows synovial fluid to penetrate the subchondral bone along with cytokines and other molecules reacting with the bone cells to increase the pathological effects.

This review gives an overview of the current thoughts on subchondral bone remodelling in osteoarthritis that is aimed at orthopaedic surgeons to help in the understanding of the pathogenesis of osteoarthritis and the role of surgical management.

Cite this article: EFORT Open Rev 2019;4 DOI: 10.1302/2058-5241.4.180102

Proteome analysis of human mesenchymal stem cells undergoing chondrogenesis when exposed to the products of various magnesium-based materials degradation

Treatment of physeal fractures (15%–30% of all paediatric fractures) remains a challenge as in approximately 10% of the cases, significant growth disturbance may occur. Bioresorbable Magnesium-based implants represent a strategy to minimize damage (i.e., load support until bone healing without second surgery). Nevertheless, the absence of harmful effects of magnesium-implants and their degradation products on the growth plate should be confirmed. Here, the proteome of human mesenchymal stem cells undergoing chondrogenesis was evaluated when exposed to the products of various Magnesium-based materials degradation. The results of this study indicate that the materials induced regulation of proteins associated with cell chondrogenesis and cartilage formation, which should be beneficial for cartilage regeneration.

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Degradation products from Mg-based materials generated changes in protein expression.

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Relevant proteins involved in cartilage formation were upregulated.

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Potential application of especially Pure-Mg and Mg-10Gd for cartilage regeneration.

Effects of mechanical loading on cortical defect repair using a novel mechanobiological model of bone healing

Mechanical loading is an important aspect of post-surgical fracture care. The timing of load application relative to the injury event may differentially regulate repair depending on the stage of healing. Here, we used a novel mechanobiological model of cortical defect repair that offers several advantages including its technical simplicity and spatially confined repair program, making effects of both physical and biological interventions more easily assessed. Using this model, we showed that daily loading (5N peak load, 2Hz, 60 cycles, 4 consecutive days) during hematoma consolidation and inflammation disrupted the injury site and activated cartilage formation on the periosteal surface adjacent to the defect. We also showed that daily loading during the matrix deposition phase enhanced both bone and cartilage formation at the defect site, while loading during the remodeling phase resulted in an enlarged woven bone regenerate. All loading regimens resulted in abundant cellular proliferation throughout the regenerate and fibrous tissue formation directly above the defect demonstrating that all phases of cortical defect healing are sensitive to physical stimulation. Stress was concentrated at the edges of the defect during exogenous loading, and finite element (FE)-modeled longitudinal strain (ε_zz) values along the anterior and posterior borders of the defect (~2200με) was an order of magnitude larger than strain values on the proximal and distal borders (~50-100με). It is concluded that loading during the early stages of repair may impede stabilization of the injury site important for early bone matrix deposition, whereas loading while matrix deposition and remodeling are ongoing may enhance stabilization through the formation of additional cartilage and bone.

Troponin-I enhances and is required for oncogenic overgrowth

Human tumors of various tissue origins show an intriguing over-expression of genes not considered oncogenes, such as that encoding Troponin-I (TnI), a well-known muscle protein. Out of the three TnI genes known in humans, the slow form, TNNI1, is affected the most. Drosophila has only one TnI gene, wupA. Here, we studied excess- and loss-of function of wupA in Drosophila, and assayed TNNI1 down regulation in human tumors growing in mice. Drosophila TnI excess-of-function increases proliferation and potentiates oncogenic mutations in Ras, Notch and Lgl genes. By contrast, TnI loss-of-function reduces proliferation and antagonizes the overgrowth due to these oncogenic mutations. Troponin-I defective cells undergo Flower- and Sparc-dependent cell competition. TnI can localize to the nucleus and its excess elicits transcriptional up-regulation of InR, Rap1 and Dilp8, which is consistent with the increased cell proliferation. Human tumor cell lines treated with a human Troponin-I peptide arrest in G₀/G_1. In addition, proliferation of non-small-cell lung carcinoma xenografts in mice is restrained by TNNI1 down-regulation. Thus, Troponin-I reveals a novel function in cell proliferation that may be of therapeutic interest in certain types of cancer.

Troponin through the looking-glass: emerging roles beyond regulation of striated muscle contraction

Troponin is a heterotrimeric Ca²⁺-binding protein that has a well-established role in regulating striated muscle contraction. However, mounting evidence points to novel cellular functions of troponin, with profound implications in cancer, cardiomyopathy pathogenesis and skeletal muscle aging. Here, we highlight the non-canonical roles and aberrant expression patterns of troponin beyond the sarcomeric milieu. Utilizing bioinformatics tools and online databases, we also provide pathway, subcellular localization, and protein-protein/DNA interaction analyses that support a role for troponin in multiple subcellular compartments. This emerging knowledge challenges the conventional view of troponin as a sarcomere-specific protein exclusively involved in muscle contraction and may transform the way we think about sarcomeric proteins, particularly in the context of human disease and aging.

Angiogenesis and Cancer Control: From Concept to Therapeutic Trial

Background

There is extraordinary interest in developing angiosuppressive agents for cancer treatment. Several new agents appear promising for the treatment of a variety of human cancers. Current concepts and new agents in clinical trials are the focus of this article. In particular, the introduction of a new treatment for human brain tumors is presented in detail, using an antiangiogenic agent, penicillamine, and depletion of an obligatory cofactor of angiogenesis, copper.

Methods

The explosive increase in literature on antiangiogenesis is reviewed using computerized search, findings presented at the recent national cancer and angiogenesis meetings. A specific protocol, NABTT 97-04, “Penicillamine and Copper Reduction for Newly Diagnosed Glioblastoma,” is presented as an example of angiotherapeutic drug discovery.

Results

A number of promising molecular approaches are being introduced to suppress tumor angiogenesis. Major categories of angiogenesis antagonists include protease inhibitors, direct inhibitors of endothelial cell proliferation and migration, suppression of angiogenic growth factors, inhibition of endothelial-specific integrin/survival signaling, chelators of copper, and inhibitors with specific other mechanisms. The preliminary results of early trials offer a glimpse into how antiangiogenesis therapy will be integrated into future care of the patient with cancer.

Conclusions

Thirty-five antiangiogenesis therapies are currently being evaluated in clinical trials. As we learn more about the fundamental mechanisms of angiogenesis, eg, the role of copper in growth factor activation, effective methods of cancer control will be implemented.

Bone Marrow Aspirate Concentrate-Enhanced Marrow Stimulation of Chondral Defects

Mesenchymal stem cells (MSCs) from bone marrow play a critical role in osteochondral repair. A bone marrow clot forms within the cartilage defect either as a result of marrow stimulation or during the course of the spontaneous repair of osteochondral defects. Mobilized pluripotent MSCs from the subchondral bone migrate into the defect filled with the clot, differentiate into chondrocytes and osteoblasts, and form a repair tissue over time. The additional application of a bone marrow aspirate (BMA) to the procedure of marrow stimulation is thought to enhance cartilage repair as it may provide both an additional cell population capable of chondrogenesis and a source of growth factors stimulating cartilage repair. Moreover, the BMA clot provides a three-dimensional environment, possibly further supporting chondrogenesis and protecting the subchondral bone from structural alterations. The purpose of this review is to bridge the gap in our understanding between the basic science knowledge on MSCs and BMA and the clinical and technical aspects of marrow stimulation-based cartilage repair by examining available data on the role and mechanisms of MSCs and BMA in osteochondral repair. Implications of findings from both translational and clinical studies using BMA concentrate-enhanced marrow stimulation are discussed.

Peripheral Nerve Fibers and Their Neurotransmitters in Osteoarthritis Pathology

The importance of the nociceptive nervous system for maintaining tissue homeostasis has been known for some time, and it has also been suggested that organogenesis and tissue repair are under neuronal control. Changes in peripheral joint innervation are supposed to be partly responsible for degenerative alterations in joint tissues which contribute to development of osteoarthritis. Various resident cell types of the musculoskeletal system express receptors for sensory and sympathetic neurotransmitters, allowing response to peripheral neuronal stimuli. Among them are mesenchymal stem cells, synovial fibroblasts, bone cells and chondrocytes of different origin, which express distinct subtypes of adrenoceptors (AR), receptors for vasoactive intestinal peptide (VIP), substance P (SP) and calcitonin gene-related peptide (CGRP). Some of these cell types synthesize and secrete neuropeptides such as SP, and they are positive for tyrosine-hydroxylase (TH), the rate limiting enzyme for biosynthesis of catecholamines. Sensory and sympathetic neurotransmitters are involved in the pathology of inflammatory diseases such as rheumatoid arthritis (RA) which manifests mainly in the joints. In addition, they seem to play a role in pathogenesis of priori degenerative joint disorders such as osteoarthritis (OA). Altogether it is evident that sensory and sympathetic neurotransmitters have crucial trophic effects which are critical for joint tissue and bone homeostasis. They modulate articular cartilage, subchondral bone and synovial tissue properties in physiological and pathophysiological conditions, in addition to their classical neurological features.

Radiosurgery Alters the Endothelial Surface Proteome: Externalized Intracellular Molecules as Potential Vascular Targets in Irradiated Brain Arteriovenous Malformations

Stereotactic radiosurgery (SRS) is an established treatment for brain arteriovenous malformations (AVMs) that drives blood vessel closure through cellular proliferation, thrombosis and fibrosis, but is limited by a delay to occlusion of 2-3 years and a maximum treatable size of 3 cm. In this current study we used SRS as a priming tool to elicit novel protein expression on the endothelium of irradiated AVM vessels, and these proteins were then targeted with prothrombotic conjugates to induce rapid thrombosis and vessel closure. SRS-induced protein changes on the endothelium in an animal model of AVM were examined using in vivo biotin labeling of surface-accessible proteins and comparative proteomics. LC-MS/MS using SWATH acquisition label-free mass spectrometry identified 280 proteins in biotin-enriched fractions. The abundance of 56 proteins increased after irradiation of the rat arteriovenous fistula (20 Gy, ≥1.5-fold). A large proportion of intracellular proteins were present in this subset: 29 mitochondrial and 9 cytoskeletal. Three of these proteins were chosen for further validation based on previously published evidence for surface localization and a role in autoimmune stimulation: cardiac troponin I (TNNI3); manganese superoxide dismutase (SOD2); and the E2 subunit of the pyruvate dehydrogenase complex (PDCE2). Immunostaining of AVM vessels confirmed an increase in abundance of PDCE2 across the vessel wall, but not a measurable increase in TNNI3 or SOD2. All three proteins co-localized with the endothelium after irradiation, however, more detailed subcellular distribution could not be accurately established. In vitro, radiation-stimulated surface translocation of all three proteins was confirmed in nonpermeabilized brain endothelial cells using immunocytochemistry. Total protein abundance increased modestly after irradiation for PDCE2 and SOD2 but decreased for TNNI3, suggesting that radiation primarily affects subcellular distribution rather than protein levels. The novel identification of these proteins as surface exposed in response to radiation raises important questions about their potential role in radiation-induced inflammation, fibrosis and autoimmunity, but may also provide unique candidates for vascular targeting in brain AVMs and other vascular tissues.

The Basic Science of Bone Marrow Aspirate Concentrate in Chondral Injuries

There has been great interest in bone marrow aspirate concentrate (BMAC) as a cost effective method in delivering mesenchymal stem cells (MSCs) to aid in the repair and regeneration of cartilage defects. Alongside MSCs, BMAC contains a range of growth factors and cytokines to support cell growth following injury. However, there is paucity of information relating to the basic science underlying BMAC and its exact biological role in supporting the growth and regeneration of chondrocytes. The focus of this review is the basic science underlying BMAC in relation to chondral damage and regeneration.

Review of the Effects of Anti-Angiogenic Compounds on the Epiphyseal Growth Plate

The formation of new blood vessels from a pre-existing vascular bed, termed “angiogenesis,” is of critical importance for the growth and development of the animal since it is required for the growth of the skeleton during endochondral ossification, development and cycling of the corpus luteum and uterus, and for the repair of tissues during wound healing. “Vasculogenesis,” the de novo formation of blood vessels is also important for the proper function and development of the vascular system in the embryo. New blood vessel formation is a prominent feature and permissive factor in the relentless progression of many human diseases, one of the most important examples of which is neoplasia. It is for this reason that angiogenesis is considered to be one of the hallmarks of cancer. The development of new classes of drugs that inhibit the growth and proper functioning of new blood vessels in vivo is likely to provide significant therapeutic benefit in the treatment of cancer, as well as other conditions where angiogenesis is a strong driver to the disease process. During the preclinical safety testing of these drugs, it is becoming increasingly clear that their in vivo efficacy is reflected in the profile of “expected toxicity” (resulting from pharmacology) observed in laboratory animals, so much so, that this profile of “desired” toxicity may act as a signature for their anti-angiogenic effect. In this article we review the major mechanisms controlling angiogenesis and its role during endochondral ossification. We also review the effects of perturbation of endochondral ossification through four mechanisms—inhibition of vascular endothelial growth factor (VEGF), pp60 c-Src kinase and matrix metalloproteinases as well as disruption of the blood supply with vascular targeting agents. Inhibition through each of these mechanisms appears to have broadly similar effects on the epiphyseal growth plate characterised by thickening due to the retention of hypertrophic chondrocytes resulting from the inhibition of angiogenesis. In contrast, in the metaphysis there are differing effects reflecting the specific role of these targets at this site.

Potential of silk fibroin/chondrocyte constructs of muga silkworm Antheraea assamensis for cartilage tissue engineering

Articular cartilage damage represents one of the most perplexing clinical problems of musculoskeletal therapeutics due to its limited self-repair and regenerative capabilities. In this study, 3D porous silk fibroin scaffolds derived from non-mulberry muga silkworm Antheraea assamensis were fabricated and examined for their ability to support cartilage tissue engineering. Additionally, Bombyx mori and Philosamia ricini silk fibroin scaffolds were utilized for comparative studies. Herein, the fabricated scaffolds were thoroughly characterized and compared for cartilaginous tissue formation within the silk fibroin scaffolds seeded with primary porcine chondrocytes and cultured in vitro for 2 weeks. Surface morphology and structural conformation studies revealed the highly interconnected porous structure (pore size 80-150 μm) with enhanced stability within their structure. The fabricated scaffolds demonstrated improved mechanical properties and were followed-up with sequential experiments to reveal improved thermal and degradation properties. Silk fibroin scaffolds of A. assamensis and P. ricini supported better chondrocyte attachment and proliferation as indicated by metabolic activities and fluorescence microscopic studies. Biochemical analysis demonstrated significantly higher production of sulphated glycosaminoglycans (sGAGs) and type II collagen in A. assamensis silk fibroin scaffolds followed by P. ricini and B. mori scaffolds (p < 0.001). Furthermore, histochemistry and immunohistochemical studies indicated enhanced accumulation of sGAGs and expression of collagen II. Moreover, the scaffolds in a subcutaneous model of rat demonstrated in vivo biocompatibility after 8 weeks of implantation. Taken together, these results demonstrate the positive attributes from the non-mulberry silk fibroin scaffold of A. assamensis and suggest its suitability as a promising scaffold for chondrocyte based cartilage repair.

ICAM-1-Targeted, Lcn2 siRNA-Encapsulating Liposomes are Potent Anti-angiogenic Agents for Triple Negative Breast Cancer

Lipocalin 2 (Lcn2) is a promising therapeutic target as well as a potential diagnostic biomarker for breast cancer. It has been previously shown to promote breast cancer progression by inducing the epithelial to mesenchymal transition in breast cancer cells as well as by enhancing angiogenesis. Lcn2 levels in urine and tissue samples of breast cancer patients has also been correlated with breast cancer status and poor patient prognosis. In this study, we have engineered a novel liposomal small interfering RNA (siRNA) delivery system to target triple negative breast cancer (TNBC) via a recently identified molecular target, intercellular adhesion molecule-1 (ICAM-1). This ICAM-1-targeted, Lcn2 siRNA- encapsulating liposome (ICAM-Lcn2-LP) binds human TNBC MDA-MB-231cells significantly stronger than non-neoplastic MCF-10A cells. Efficient Lcn2 knockdown by ICAM-Lcn2-LPs led to a significant reduction in the production of vascular endothelial growth factor (VEGF) from MDA-MB-231 cells, which, in turn, led to reduced angiogenesis both in vitro and in vivo. Angiogenesis (neovascularization) is a requirement for solid tumor growth and progression, and its inhibition is an important therapeutic strategy for human cancers. Our results indicate that a tumor-specific strategy such as the TNBC-targeted, anti-angiogenic therapeutic approach developed here, may be clinically useful in inhibiting TNBC progression.

TNNI1, TNNI2 and TNNI3: Evolution, regulation, and protein structure-function relationships

Troponin I (TnI) is the inhibitory subunit of the troponin complex in the sarcomeric thin filament of striated muscle and plays a central role in the calcium regulation of contraction and relaxation. Vertebrate TnI has evolved into three isoforms encoded by three homologous genes: TNNI1 for slow skeletal muscle TnI, TNNI2 for fast skeletal muscle TnI and TNNI3 for cardiac TnI, which are expressed under muscle type-specific and developmental regulations. To summarize the current knowledge on the TnI isoform genes and products, this review focuses on the evolution, gene regulation, posttranslational modifications, and structure-function relationship of TnI isoform proteins. Their physiological and medical significances are also discussed.

Advancement of the Subchondral Bone Plate in Translational Models of Osteochondral Repair: Implications for Tissue Engineering Approaches

Subchondral bone plate advancement is of increasing relevance for translational models of osteochondral repair in tissue engineering (TE). Especially for therapeutic TE approaches, a basic scientific knowledge of its chronological sequence, possible etiopathogenesis, and clinical implications are indispensable. This review summarizes the knowledge on this topic gained from a total of 31 translational investigations, including 1009 small and large animals. Experimental data indicate that the advancement of the subchondral bone plate frequently occurs during the spontaneous repair of osteochondral defects and following established articular cartilage repair approaches for chondral lesions such as marrow stimulation and TE-based strategies such as autologous chondrocyte implantation. Importantly, this subchondral bone reaction proceeds in a defined chronological and spatial pattern, reflecting both endochondral ossification and intramembranous bone formation. Subchondral bone plate advancement arises earlier in small animals and defects, but is more pronounced at the long term in large animals. Possible etiopathologies comprise a disturbed subchondral bone/articular cartilage crosstalk and altered biomechanical conditions or neovascularization. Of note, no significant correlation was found so far between subchondral bone plate advancement and articular cartilage repair. This evidence from translational animal models adverts to an increasing awareness of this previously underestimated pathology. Future research will shed more light on the advancement of the subchondral bone plate in TE models of cartilage repair.

The mRNA expressions and immunohistochemistry of factors involved in angiogenesis and lymphangiogenesis in the early stage of rat skin incision wounds

Wound healing evaluation is important in forensic pathology, in which angiogenesis plays an important role. We have already shown that vascular endothelial growth factor A (VEGF) is produced in the rat skin incision wounds by neutrophils, endothelial cells, and fibroblasts. In this study, we assessed the changes in the mRNA expressions of various factors possibly involved in angiogenesis including angiopoietin (ANGPT) 1 and 2, cadherin 5 (CDH5), granulocyte-macrophage colony stimulating factor (CSF2/GM-CSF), granulocyte colony stimulating factor (CSF3/G-CSF), chemokine (C-X-C motif) ligand 2 (CXCL2), chemokine (C-X-C motif) ligand12 (CXCL12/SDF1), endothelin 1 (ET1), fibroblast growth factor 1 (FGF 1), hepatocyte growth factor (HGF), hypoxia inducible factor 1 alpha (HIF1a), leptin, matrix metallopepitidase 9 (MMP9), serpine/plasminogen activator inhibitor1 (PAI1), platelet-derived growth factor-A (PDGF-A), transforming growth factor alpha and beta 1 (TGFa and b1), tenomodulin (TNMD), and troponin I type 2 (TNNI2) in the early stage of the rat skin incision wounds by real time RT-PCR. Factors reported to be involved in lymphangiogenesis such as fibroblast growth factor 2 (FGF 2), c-fos induced growth factor (FIGF/VEGF-D), forkhead box C2 (FOXC2), and prospero homeobox 1 (PROX1) were also studied. One and 3 days after the dorsal skin incisions, wounds on male Sprague-Dawley rats showed the statistically significant increases in the mRNA expressions for CXCL2, CSF3, MMP9, PAI1, and CSF2, whereas TGFa, TNNI2, FGF1, TNMD, leptin, and CXCL12 showed the statistically significant decreases. Interestingly, lymphgangiogenic factors FOXC2, PROX1, and FGF2 also showed the statistically significant decreases. In situ hybridization and immunohistochemistry showed the mRNA and protein positivity in endothelial cells, fibroblasts, and some leukocytes at the bottom of the wound tissue for PAI1, CSF3, and MMP9, 1 day after the skin incisions. Our novel findings show the possible involvement of several factors involved in angiogenesis and lymphangiogenesis in the early stage of wound healing process, which may be useful for forensic wound evaluations.

A gain-of-function mutation in Tnni2 impeded bone development through increasing Hif3a expression in DA2B mice

Distal arthrogryposis type 2B (DA2B) is an important genetic disorder in humans. However, the mechanisms governing this disease are not clearly understood. In this study, we generated knock-in mice carrying a DA2B mutation (K175del) in troponin I type 2 (skeletal, fast) (TNNI2), which encodes a fast-twitch skeletal muscle protein. Tnni2^K175del mice (referred to as DA2B mice) showed typical DA2B phenotypes, including limb abnormality and small body size. However, the current knowledge concerning TNNI2 could not explain the small body phenotype of DA2B mice. We found that Tnni2 was expressed in the osteoblasts and chondrocytes of long bone growth plates. Expression profile analysis using radii and ulnae demonstrated that Hif3a expression was significantly increased in the Tnni2^K175del mice. Chromatin immunoprecipitation assays indicated that both wild-type and mutant tnni2 protein can bind to the Hif3a promoter using mouse primary osteoblasts. Moreover, we showed that the mutant tnni2 protein had a higher capacity to transactivate Hif3a than the wild-type protein. The increased amount of hif3a resulted in impairment of angiogenesis, delay in endochondral ossification, and decrease in chondrocyte differentiation and osteoblast proliferation, suggesting that hif3a counteracted hif1a-induced Vegf expression in DA2B mice. Together, our data indicated that Tnni2^K175del mutation led to abnormally increased hif3a and decreased vegf in bone, which explain, at least in part, the small body size of Tnni2^K175del mice. Furthermore, our findings revealed a new function of tnni2 in the regulation of bone development, and the study of gain-of-function mutation in Tnni2 in transgenic mice opens a new avenue to understand the pathological mechanism of human DA2B disorder.

Distal arthrogryposis type 2B (DA2B) is an autosomal dominant genetic disorder. The typical clinical features of DA2B include hand and/or foot contracture and shortness of stature in patients. To date, mutations in TNNI2 can explain approximately 20% of familial incidences of DA2B. TNNI2 encodes a subunit of the Tn complex, which is required for calcium-dependent fast twitch muscle fiber contraction. In the absence of Ca²⁺ ions, TNNI2 impedes sarcomere contraction. Here, we reported a knock-in mouse carrying a DA2B mutation TNNI2 (K175del) had typical limb abnormality and small body size that observed in human DA2B. However, the small body did not seem to be convincingly explained using the present knowledge of TNNI2 associated skeletal muscle contraction. Our findings showed that the Tnni2^K175del mutation impaired bone development of Tnni2^K175del mice. Our data further showed that the mutant tnni2 protein had a higher capacity to transactivate Hif3a than the wild-type protein and led to a reduction in Vegf expression in bone of DA2B mice. Taken together, our findings demonstrated that the disease-associated Tnni2^K175del mutation caused bone defects, which accounted for, at least in part, the small body size of Tnni2^K175del mice. Our data also suggested, for the first time, a novel role of tnni2 in the regulation of bone development of mice by affecting Hif-vegf signaling.

Matrilin-1 is an inhibitor of neovascularization

In the course of conducting a series of studies whose goal was to discover novel endogenous angiogenesis inhibitors, we have purified matrilin-1 (MATN-1) and have demonstrated, for the first time, that it inhibits neovascularization both in vitro and in vivo. Proteins were extracted from cartilage using a 2 m NaCl, 0.01 m HEPES buffer at 4 °C, followed by concentration of the extract. The concentrate was fractionated by size exclusion chromatography, and fractions were then screened for their ability to inhibit capillary endothelial cell (EC) proliferation in vitro. Fractions containing EC inhibitory activity were pooled and further purified by cation exchange chromatography. The resulting fractions from this step were then screened to isolate the antiangiogenic activity in vitro. This activity was identified by tandem mass spectrometry as being MATN-1. Human MATN-1 was cloned and expressed in Pichia pastoris and purified to homogeneity. Purified recombinant MATN-1, along with purified native protein, was shown to inhibit angiogenesis in vivo using the chick chorioallantoic membrane assay by the inhibition of capillary EC proliferation and migration. Finally, using a MATN-1-deficient mouse, we showed that angiogenesis during fracture healing was significantly higher in MATN-1(-/-) mice compared with the wild type mice as demonstrated by in vivo imaging and by elevated expression of angiogenesis markers including PECAM1, VEGFR, and VE-cadherin.

Novel functions for type II procollagen

Cartilage is unique in being established as an avascular tissue during development. Cartilage also has the property of being resistant to tumor invasion with tumors arising on the periphery of cartilage and in bone, but sparing the cartilage. These properties have been investigated for many years beginning in the 1970's. Many anti-angiogenic molecules have been isolated from cartilage in small amounts. Portions of molecules from cartilage also possess anti-angiogenic properties when released from the parent protein by degradative extracellular enzymes. This review highlights a new anti-angiogenic and anti-tumor moiety from cartilage, the NH2-propeptide of type IIB collagen. When released from the procollagen during synthesis, the propeptide has the capacity to act on its own to protect the cartilage by killing of endothelial cell, osteoclasts and tumor cells.

Skeletal Muscle Troponin I (TnI) in Animal Fat Tissues to Be Used as Biomarker for the Identification of Fat Adulteration

In this study, the existence of skeletal muscle troponin I (smTnI), well-known as a muscle protein in fat tissues, and the utilization of smTnI as a biomarker for the identification of fat adulteration were investigated. A commercial antibody (ab97427) specific to all of animals smTnI was used in this study. Fat and meat samples (cooked and non-cooked) of pork and beef, and chicken considered as representative meats were well minced and extracted by heating and non-heating methods, and the extracts from fat and meat tissues were probed by the antibody used in both enzyme-linked immunosorbent assay (ELISA) and immunoblot. The antibody exhibited a strong reaction to all meat and fat extracts in ELISA test. On the other hand, the results of immunoblot analsis revealed a 23 kDa high intensity band corresponding to the molecular weight of smTnI (23786 Da). These results demonstrate that the existence of smTnI in all animal fat tissues. Since there are monoclonal antibodies specific to each species smTnI, smTnI in fat tissues could be used as a biomarker to identify or determine animal species adulterated in meat products. Therefore, an analytical method to identify fraudulent fat adulteration can be developed with an antibody specific to each species smTnI.

Transcriptome sequencing reveals differences between primary and secondary hair follicle-derived dermal papilla cells of the Cashmere goat (Capra hircus)

The dermal papilla is thought to establish the character and control the size of hair follicles. Inner Mongolia Cashmere goats (Capra hircus) have a double coat comprising the primary and secondary hair follicles, which have dramatically different sizes and textures. The Cashmere goat is rapidly becoming a potent model for hair follicle morphogenesis research. In this study, we established two dermal papilla cell lines during the anagen phase of the hair growth cycle from the primary and secondary hair follicles and clarified the similarities and differences in their morphology and growth characteristics. High-throughput transcriptome sequencing was used to identify gene expression differences between the two dermal papilla cell lines. Many of the differentially expressed genes are involved in vascularization, ECM-receptor interaction and Wnt/β-catenin/Lef1 signaling pathways, which intimately associated with hair follicle morphogenesis. These findings provide valuable information for research on postnatal morphogenesis of hair follicles.

Prefabrication of 3D cartilage contructs: towards a tissue engineered auricle--a model tested in rabbits

The reconstruction of an auricle for congenital deformity or following trauma remains one of the greatest challenges in reconstructive surgery. Tissue-engineered (TE) three-dimensional (3D) cartilage constructs have proven to be a promising option, but problems remain with regard to cell vitality in large cell constructs. The supply of nutrients and oxygen is limited because cultured cartilage is not vascular integrated due to missing perichondrium. The consequence is necrosis and thus a loss of form stability. The micro-surgical implantation of an arteriovenous loop represents a reliable technology for neovascularization, and thus vascular integration, of three-dimensional (3D) cultivated cell constructs. Auricular cartilage biopsies were obtained from 15 rabbits and seeded in 3D scaffolds made from polycaprolactone-based polyurethane in the shape and size of a human auricle. These cartilage cell constructs were implanted subcutaneously into a skin flap (15×8 cm) and neovascularized by means of vascular loops implanted micro-surgically. They were then totally enhanced as 3D tissue and freely re-implanted in-situ through microsurgery. Neovascularization in the prefabricated flap and cultured cartilage construct was analyzed by microangiography. After explantation, the specimens were examined by histological and immunohistochemical methods. Cultivated 3D cartilage cell constructs with implanted vascular pedicle promoted the formation of engineered cartilaginous tissue within the scaffold in vivo. The auricles contained cartilage-specific extracellular matrix (ECM) components, such as GAGs and collagen even in the center oft the constructs. In contrast, in cultivated 3D cartilage cell constructs without vascular pedicle, ECM distribution was only detectable on the surface compared to constructs with vascular pedicle. We demonstrated, that the 3D flaps could be freely transplanted. On a microangiographic level it was evident that all the skin flaps and the implanted cultivated constructs were well neovascularized. The presented method is suggested as a promising alternative towards clinical application of engineered cartilaginous tissue for plastic and reconstructive surgery.

Biomaterials and biotechnology: from the discovery of the first angiogenesis inhibitors to the development of controlled drug delivery systems and the foundation of tissue engineering

This paper describes the discovery of the first inhibitors of angiogenesis; the discoveries that led to the development of the first biocompatible controlled release systems for macromolecules, and findings that helped to create the field of tissue engineering. In addition, new paradigms for creating biomaterials, early work on nanotechnology in medicine and intelligent drug delivery systems are discussed.

A two-step method of constructing mature cartilage using bone marrow-derived mesenchymal stem cells

Bone marrow-derived mesenchymal stem cells (BMSCs) are a promising source of stem cells for tissue engineering in cartilage repair. However, construction of cartilage using BMSCs can involve many problems, such as fibrosis, vascularization, the 'hollow' phenomenon and shrinkage, which may be caused by the incomplete differentiation of BMSCs and prevent the clinical application of tissue-engineered cartilage. A novel induction system that facilitates chondrogenesis by swine BMSCs has been developed. In this study, we constructed cartilage using a two-step procedure: first, promoting complete chondrogenic differentiation of BMSCs in 8 weeks, and second, these chondrocytes which differentiated from BMSCs in vitro were provided with a three-dimensional scaffold, which was then implanted subcutaneously. The results indicate that this two-step construction procedure can promote the full chondrogenic differentiation of BMSCs in vitro and the formation of mature ectopic cartilage by BMSCs in vivo.

Lipocalin 2 is a novel regulator of angiogenesis in human breast cancer

Lipocalin 2 (Lcn2), a member of the lipocalin family, is up-regulated in a variety of epithelial cancers. We have previously reported that Lcn2 induces the epithelial to mesenchymal transition in breast cancer through the estrogen receptor α/Slug axis and that it is a potential noninvasive biomarker of this disease. Here, we report the novel finding that Lcn2 regulates breast cancer angiogenesis. Vascular endothelial growth factor (VEGF), a key angiogenic activator, was significantly increased with Lcn2 expression in MCF-7 human breast cancer cells as well as in an angiogenic line derived from MDA-MB-436 cells. Treatment with a VEGF-neutralizing antibody demonstrates that VEGF is essential for the angiogenic activity of Lcn2. We further demonstrate that Lcn2-induced VEGF is mediated through hypoxia-inducible factor 1α (HIF-1α) and that Lcn2 regulates HIF-1α through extracellular signal-regulated kinase (Erk). The regulation of HIF-1α and VEGF by Lcn2 was also demonstrated in the aggressive MDA-MB-231 cell line. Using the mouse corneal pocket assay, we found that Lcn2 significantly enhanced the angiogenesis induced by VEGF. Taken together, these results are the first to demonstrate that Lcn2 promotes angiogenesis in vitro and in vivo and suggest a novel mechanism through which Lcn2 may promote tumor progression.

Osteochondral alterations in osteoarthritis

Osteoarthritis (OA) is a major cause of pain and disability in the aging population, but its pathogenesis remains incompletely understood. Alterations beneath the articular cartilage at the osteochondral junction are attracting interest as possible mediators of pain and structural progression in OA. Osteochondral changes occur early during the development of OA and may aggravate pathology elsewhere in the joint. Loss of osteochondral integrity removes the barrier between intra-articular and subchondral compartments, exposing subchondral bone and its nerves to abnormal chemical and biomechanical influence. Osteochondral plasticity results in a merging of tissue compartments across the junction. Loss of the clearly differentiated demarcation between bone and articular cartilage is associated with invasion of articular cartilage by blood vessels and sensory nerves, and advancing endochondral ossification. Increased subchondral bone turnover is intimately associated with these alterations at the osteochondral junction. Cells signal across the osteochondral junction, and this cross-talk may be both a consequence of, and contribute to these pathological changes. Bone turnover, angiogenesis and nerve growth are also features of other diseases such as osteoporosis and cancers, for which therapeutic interventions are already advanced in their development. Here we review pathological changes at the osteochondral junction and explore their potential therapeutic implications for OA. This article is part of a Special Issue entitled "Osteoarthritis".

Inhibitory effect of 5,8,11-eicosatrienoic acid on angiogenesis

INTRODUCTION

Cartilage contains high levels of n-9 eicosatrienoic acid (20:3n-9) but no blood vessels. 20:3n-9 might inhibit angiogenesis.

MATERIALS AND METHODS

Angiogenesis was measured in human umbilical vein endothelial cells and diploid fibroblasts. Co-culture was performed with vascular endothelial growth factor-A (VEGF-A, 10 ng/mL) and fatty acids (0.1-10 μmol/L). After 10 days of incubation and immunostaining for endothelial cells, vessel areas were calculated with image analyser software.

RESULTS

Addition of 20:3n-9 and n-3 eicosatrienoic acid (20:3n-3) dose dependently inhibited VEGF-A-stimulated angiogenesis (more than the positive control suramin). Arachidonic, eicosapentaenoic, dihomo-γ-linolenic (20:3n-6) and oleic acids did not affect VEGF-A-stimulated angiogenesis even at 10 μmol/L. Arachidonic and dihomo-γ-linolenic acids enhanced angiogenesis without VEGF-A.

DISCUSSION AND CONCLUSIONS

We suggest that the presence of 20:3n-9 in cartilage may be related to its vessel-free status and that 20:3n-9 may be useful for the treatment of disorders with excessive vasculature.

ACKNOWLEDGEMENTS

This work was partly supported by Polyene Project, Inc.

Mechanisms and targets of angiogenesis and nerve growth in osteoarthritis

During osteoarthritis (OA), angiogenesis is increased in the synovium, osteophytes and menisci and leads to ossification in osteophytes and the deep layers of articular cartilage. Angiogenic and antiangiogenic factors might both be upregulated in the osteoarthritic joint; however, vascular growth predominates, and the articular cartilage loses its resistance to vascularization. In addition, blood vessel growth is increased at--and disrupts--the osteochondral junction. Angiogenesis in this location is dependent on the creation of channels from subchondral bone spaces into noncalcified articular cartilage. Inflammation drives synovial angiogenesis through macrophage activation. Blood vessel and nerve growth are linked by common pathways that involve the release of proangiogenic factors, such as vascular endothelial growth factor, β-nerve growth factor and neuropeptides. Proangiogenic factors might also stimulate nerve growth, and molecules produced by vascular cells could both stimulate and guide nerve growth. As sensory nerves grow along new blood vessels in osteoarthritic joints, they eventually penetrate noncalcified articular cartilage, osteophytes and the inner regions of menisci. Angiogenesis could, therefore, contribute to structural damage and pain in OA and provide potential targets for new treatments.

Antiangiogenic and anticancer molecules in cartilage

Cartilage is one of the very few naturally occurring avascular tissues where lack of angiogenesis is the guiding principle for its structure and function. This has attracted investigators who have sought to understand the biochemical basis for its avascular nature, hypothesising that it could be used in designing therapies for treating cancer and related malignancies in humans through antiangiogenic applications. Cartilage encompasses primarily a specialised extracellular matrix synthesised by chondrocytes that is both complex and unique as a result of the myriad molecules of which it is composed. Of these components, a few such as thrombospondin-1, chondromodulin-1, the type XVIII-derived endostatin, SPARC (secreted protein acidic and rich in cysteine) and the type II collagen-derived N-terminal propeptide (PIIBNP) have demonstrated antiangiogenic or antitumour properties in vitro and in vivo preclinical trials that involve several complicated mechanisms that are not completely understood. Thrombospondin-1, endostatin and the shark-cartilage-derived Neovastat preparation have also been investigated in human clinical trials to treat several different kinds of cancers, where, despite the tremendous success seen in preclinical trials, these molecules are yet to show success as anticancer agents. This review summarises the current state-of-the-art antiangiogenic characterisation of these molecules, highlights their most promising aspects and evaluates the future of these molecules in antiangiogenic applications.

Chondrogenic differentiation of induced pluripotent stem cells from osteoarthritic chondrocytes in alginate matrix

Induced pluripotent stem cells (iPSCs) have the potential to revolutionise cell therapy; however, it remains unclear whether iPSCs can be generated from human osteoarthritic chondrocytes (OCs) and subsequently induced to differentiate into chondrocytes. In the present study, we investigated the differentiation potential of OCs into iPSCs using defined transcription factors and explored the possibility of using these OC-derived iPSCs for chondrogenesis. Our study demonstrates that iPSCs can be generated from OCs and that these iPSCs are indistinguishable from human embryonic stem cells (hESCs). To promote chondrogenic differentiation, we used lentivirus to transduce iPSCs seeded in alginate matrix with transforming growth factor-β1 (TGF-β1) and then in vitro co-cultured these iPSCs with chondrocytes. Gene expression analysis showed that this combinational strategy promotes the differentiation of the established iPSCs into chondrocytes in alginate matrix. Increased expression of cartilage-related genes, including collagen II, aggrecan, and cartilage oligomeric matrix protein (COMP), and decreased gene expression of the degenerative cartilage marker, vascular endothelial growth factor (VEGF), were observed. The histological results revealed a dense sulphated extracellular matrix in the co-culture of TGF-β1-transfected iPSCs with chondrocytes in alginate matrix. Additionally, in vivo chondroinductive activity was also evaluated. Histological examination revealed that more new cartilage was formed in the co-culture of TGF-β1-transfected iPSCs with chondrocytes in alginate matrix. Taken together, our data indicate that iPSCs can be generated from OCs by defined factors and the combinational strategy results in significantly improved chondrogenesis of OC-derived iPSCs. This work adds to our understanding of potential solutions to osteoarthritic cell replacement problem.

Tumor angiogenesis as a target for dietary cancer prevention

Between 2000 and 2050, the number of new cancer patients diagnosed annually is expected to double, with an accompanying increase in treatment costs of more than $80 billion over just the next decade. Efficacious strategies for cancer prevention will therefore be vital for improving patients' quality of life and reducing healthcare costs. Judah Folkman first proposed antiangiogenesis as a strategy for preventing dormant microtumors from progressing to invasive cancer. Although antiangiogenic drugs are now available for many advanced malignancies (colorectal, lung, breast, kidney, liver, brain, thyroid, neuroendocrine, multiple myeloma, myelodysplastic syndrome), cost and toxicity considerations preclude their broad use for cancer prevention. Potent antiangiogenic molecules have now been identified in dietary sources, suggesting that a rationally designed antiangiogenic diet could provide a safe, widely available, and novel strategy for preventing cancer. This paper presents the scientific, epidemiologic, and clinical evidence supporting the role of an antiangiogenic diet for cancer prevention.

A polypeptide from shark troponin I can inhibit angiogenesis and tumor growth

The shark troponin I gene (TnI) was found for the first time in this study to inhibit endothelial cell proliferation and angiogenesis. This shark TnI had 68.9% amino acid homology with human TnI, whereas the polypeptide from Lys91 to Leu123, which is thought to be the active site of TnI, had 78.8% homology with the corresponding fragment of human TnI. However, the polypeptide of shark had higher activity to inhibit the proliferation of HUVEC and tumor cell lines than that of human TnI. To investigate the anti-angiogenesis and anti-tumor effect of the shark TnI polypeptide, the DNA sequence of polypeptide (Lys91-Leu123) of white-spot catshark TnI(psTnI) was cloned and fused with the His-SUMO cDNA, followed by expression in Escherichia coli. After its purification by Ni(2+) affinity chromatography, the fusion His-SUMO-psTnI protein was digested with the SUMO enzyme to release psTnI. The inhibitory ability of this recombinant shark TnI polypeptide for angiogenesis was confirmed by chicken embryo allantoic membrane (CAM) test and IHC analysis. It was also found by breast carcinoma xenograft study in Balb/c mice that this polypeptide could inhibit tumor growth in vivo.

The molecular pathogenesis of osteosarcoma: a review

Osteosarcoma is the most common primary malignancy of bone. It arises in bone during periods of rapid growth and primarily affects adolescents and young adults. The 5-year survival rate for osteosarcoma is 60%-70%, with no significant improvements in prognosis since the advent of multiagent chemotherapy. Diagnosis, staging, and surgical management of osteosarcoma remain focused on our anatomical understanding of the disease. As our knowledge of the molecular pathogenesis of osteosarcoma expands, potential therapeutic targets are being identified. A comprehensive understanding of these mechanisms is essential if we are to improve the prognosis of patients with osteosarcoma through tumour-targeted therapies. This paper will outline the pathogenic mechanisms of osteosarcoma oncogenesis and progression and will discuss some of the more frontline translational studies performed to date in search of novel, safer, and more targeted drugs for disease management.

Induction of the fibrinolytic system by cartilage extract mediates its antiangiogenic effect in mouse glioma

Both the antiangiogenic and antitumoral activity of shark cartilage extracts (SCE) have been demonstrated in animal models and clinical trials. Studies reported that SCE induces the expression of tissue plasminogen activator gene (PLAT) in endothelial cells and increases the activity of the protein (t-PA) in vitro. The aim of this study was to demonstrate the crucial role of t-PA induction in the antiangiogenic and antitumor activity of SCE in experimental glioma. This study showed antiangiogenic and antitumoral effects of SCE in three mice glioma models (C6, HGD and GL26). Histological examination suggested perivascular proteolysis and edema as well as important intratumoral necrosis, which artefactually increased the tumor volume at high doses. Thus, the antiangiogenic effect of SCE correlated with the presence of t-PA and angiostatin in degenerating vessels. Functional in vivo experiments were conducted to modulate the plasminogen pathway. No antiangiogenic effect was observed on tumors overexpressing the plasminogen activator inhibitor-1 (PAI-1). Moreover, therapeutical effects were neutralized in mice that were cotreated with ε-aminocaproic acid (EACA, 120 mg/kg p.o.), an inhibitor that blocks the high-affinity lysine binding sites of both plasminogen and plasmin. In contrast, cotreatment with N-acetylcysteine (NAC, 7,5mg/kg i.p.), a sulfhydril donor that reduces plasmin into angiostatin or other antiangiogenic fragments, increased the benefit of SCE on mice survival. In subcutaneous models, NAC prevented the increase in tumor volume caused by high doses of cartilage extract. In conclusion, this study indicates that induction of t-PA by shark cartilage extract plays an essential role in its antiangiogenic activity, but that control of excessive proteolysis by a plasmin reductor could prevent edema and uncover the full benefit of shark cartilage extract in the treatment of intracranial tumors.

Rapid remodeling of airway vascular architecture at birth

Recent advances have documented the development of lung vasculature before and after birth, but less is known of the growth and maturation of airway vasculature. We sought to determine whether airway vasculature changes during the perinatal period and when the typical adult pattern develops. On embryonic day 16.5 mouse tracheas had a primitive vascular plexus unlike the adult airway vasculature, but instead resembling the yolk sac vasculature. Soon after birth (P0), the primitive vascular plexus underwent abrupt and extensive remodeling. Blood vessels overlying tracheal cartilage rings regressed from P1 to P3 but regrew from P4 to P7 to form the hierarchical, segmented, ladder-like adult pattern. Hypoxia and HIF-1α were present in tracheal epithelium over vessels that survived but not where they regressed. These findings reveal the plasticity of airway vasculature after birth and show that these vessels can be used to elucidate factors that promote postnatal vascular remodeling and maturation.