Effect of the heparinoid pentosan polysulphate (SP 54) on the functional properties of cultured bovine aortic endothelial cells

Pentosan Polysulphate (PPS), a Semi-Synthetic Heparinoid DMOAD With Roles in Intervertebral Disc Repair Biology emulating The Stem Cell Instructive and Tissue Reparative Properties of Heparan Sulphate

This review highlights the attributes of pentosan polysulphate (PPS) in the promotion of intervertebral disc (IVD) repair processes. PPS has been classified as a disease modifying osteoarthritic drug (DMOAD) and many studies have demonstrated its positive attributes in the countering of degenerative changes occurring in cartilaginous tissues during the development of osteoarthritis (OA). Degenerative changes in the IVD also involve inflammatory cytokines, degradative proteases and cell signalling pathways similar to those operative in the development of OA in articular cartilage. PPS acts as a heparan sulphate (HS) mimetic to effect its beneficial effects in cartilage. The IVD contains small cell membrane HS-proteoglycans (HSPGs) such as syndecan, and glypican and a large multifunctional HS/chondroitin sulphate (CS) hybrid proteoglycan (HSPG2/perlecan) that have important matrix stabilising properties and sequester, control and present growth factors from the FGF, VEGF, PDGF and BMP families to cellular receptors to promote cell proliferation, differentiation and matrix synthesis. HSPG2 also has chondrogenic properties and stimulates the synthesis of extracellular matrix (ECM) components, expansion of cartilaginous rudiments and has roles in matrix stabilisation and repair. Perlecan is a perinuclear and nuclear proteoglycan in IVD cells with roles in chromatin organisation and control of transcription factor activity, immunolocalises to stem cell niches in cartilage, promotes escape of stem cells from quiescent recycling, differentiation and attainment of pluripotency and migratory properties. These participate in tissue development and morphogenesis, ECM remodelling and repair. PPS also localises in the nucleus of stromal stem cells, promotes development of chondroprogenitor cell lineages, ECM synthesis and repair and discal repair by resident disc cells. The availability of recombinant perlecan and PPS offer new opportunities in repair biology. These multifunctional agents offer welcome new developments in repair strategies for the IVD.

Comparative study on the in vitro and in vivo activities of heparinoids derivative investigated on the animal model

In this study we compared the antithrombotic and anticoagulant properties of sodium and calcium derivatives of pentosan polysulfate (Na-PPS, Ca-PPS), unfractionated heparin (UFH), and low-molecular-weight heparin (Fraxiparin). The antithrombotic effects of these agents have been investigated in an experimental thrombosis model in which rat mesenteric venules with a diameter of 20-30 microm were injured by well-defined argon laser lesions. Furthermore, the in vivo and in vitro anticoagulant activities [activated partial thromboplastin time (aPTT), Heptest] of these agents have been studied. Thrombus formation was significantly inhibited after s.c. injection of Na-PPS and Ca-PPS in doses >10 mg/kg. The duration of the antithrombotic effect lasted 8 h for Na-PPS and 12 h for Ca-PPS. After oral administration of Na-PPS, an antithrombotic effect was not observed. Oral application of Ca-PPS in doses >20 mg/kg significantly inhibited thrombus formation. Na-PPS and Ca-PPS markedly prolonged clotting time in aPTT and Heptest in concentrations ranging from 0.01 to 0.2 mg/ml rat PTT. Two h after s.c. administration of these agents in a dose of 10 mg/kg, the aPTT increased threefold and the Heptest 2.5-fold compared with controls. After oral application of 50 mg/kg Na-PPS and Ca-PPS, no effect on the coagulation test could be measured. Intravenous injection of UFH prolonged the Heptest after 1 min and the aPTT after 30 min. In ex vivo studies of aPTT and Heptest performed in rat plasma between 2 and 24 h after s.c. injection of 0.2 mg/kg Fraxiparin, no inhibition of any coagulation test was measured. The antithrombotic effect of 0.2 mg/kg Fraxiparin after s.c. injection was significant. Intravenous injection of 20 U/kg UFH significantly inhibited thrombus formation. The smallest antithrombotic effect was after i.v. injection of UFH.

The pathobiology of osteoarthritis and the rationale for the use of pentosan polysulfate for its treatment

OBJECTIVES

Structure-modifying osteoarthritis (OA) drugs (SMOADs) may be defined as agents that reverse, retard, or stabilize the underlying pathology of OA, thereby providing symptomatic relief in the long-term. The objective of this review was to evaluate the literature on sodium pentosan polysulfate (NaPPS) and calcium pentosan polysulfate (CaPPS), with respect to the pathobiology of OA to ascertain whether these agents should be classified as SMOADs.

METHODS

Published studies on NaPPS and CaPPS were selected on the basis of their relevance to the known pathobiology of OA, which also was reviewed.

RESULTS

Both NaPPS and CaPPS exhibit a wide range of pharmacological activities. Of significance was the ability of these agents to support chondrocyte anabolic activities and attenuate catabolic events responsible for loss of components of the cartilage extracellular matrix in OA joints. Although some of the anti-catabolic activities may be mediated through direct enzyme inhibition, NaPPS and CaPPS also have been shown to enter chondrocytes and bind to promoter proteins and alter gene expression of matrix metalloproteinases and possibly other mediators. In rat models of arthritis, NaPPS and CaPPS reduced joint swelling and inflammatory mediator levels in pouch fluids. Moreover, synoviocyte biosynthesis of high-molecular-weight hyaluronan, which is diminished in OA, was normalized when these cells were incubated with NaPPS and CaPPS or after intraarticular injection of NaPPS into arthritic joints. In rabbit, canine, and ovine models of OA, NaPPS and CaPPS preserved cartilage integrity, proteoglycan synthesis, and reduced matrix metalloproteinase activity. NaPPS and CaPPS stimulated the release of tissue plasminogen activator (t-PA), superoxide dismutase, and lipases from vascular endothelium while concomitantly decreasing plasma levels of the endogenous plasminogen activator inhibitor PAI-1. The net thrombolytic and lipolytic effects exhibited by NaPPS and CaPPS may serve to improve blood flow through subchondral capillaries of OA joints and improve bone cell nutrition. In geriatric OA dogs, NaPPS and CaPPS reduced symptoms, as well as normalized their thrombolytic status, threshold for platelet activation, and plasma triglyceride levels. These hematologic parameters were shown to be abnormal in OA animals before drug treatment. Similar outcomes were observed in OA patients when CaPPS or NaPPS were given orally or parenterally in both open and double-blind trials.

CONCLUSIONS

The data presented in this review support the contention that NaPPS and CaPPS should be classified as SMOADs. However, additional long-term clinical studies employing methods of assessing joint structural changes will be needed to confirm this view.

Activation of the high affinity nerve growth factor receptor by two polyanionic chemotherapeutic agents: role in drug induced neurotoxicity

Suramin is a polyanionic chemotherapeutic agent which causes severe peripheral neuropathy. The mechanisms of antineoplastic and neurotoxic activities are still poorly understood. Interference with growth factor receptor function has been suggested for suramin's chemotherapeutic function. Previous studies from our laboratory have demonstrated that suramin interfered with the function of nerve growth factor (NGF) and induced lysosomal storage defects within dorsal root ganglion neurons. Pentosan polysulfate (PPS) was used as another polyanionic agent, to compare these two cellular functions; NGF receptor interaction and disruption in glycolipid metabolism. Like suramin and NGF, PPS induced neurite outgrowth from the PC12 cell line which correlated with tyrosine phosphorylation of the high affinity NGF receptor (TrkA/gpl40) and ERK-1/MAP kinase. Ultrastructural studies of dorsal root ganglion exposed to PPS for various time periods were normal. This contrasted with suramin exposed cultures which consistently developed lamellar inclusion bodies (LIB) within 6 h. LIB formation with suramin treatment was associated with neuronal cell death, while PPS treatment did not cause any neurotoxic effects. These results indicated that PPS mimicked the effect of suramin on NGF receptors but did not cause similar accumulation of LIB. This suggested that the effect of polyanionic compounds on TrkA was not involved in LIB accumulation and subsequent induction of neurotoxicity.

The effects of intravesical pretreatment with pentosan polysulfate on the bacillus Calmette-Guérin induced immune reaction of the guinea pig

Immunotherapy with intravesical instillation of bacillus Calmette-Guérin (BCG) is an effective treatment for superficial bladder carcinoma. In the present study the BCG-induced immunological reaction in the guinea pig (PPD skin test, bladder wall infiltrates and number of cells in the iliac lymph nodes) was investigated after intravesical pretreatment with pentosan polysulphate (PPS), which modulated BCG attachment to the bladder wall. Pentosan polysulfate is a molecule comparable to the naturally occurring glycosaminoglycans (GAGs) of the bladder mucosa. The data obtained after six weekly instillations of BCG-RIVM (5 x 10(6) - 5 x 10(7) cfu) with or without preinstillation with PPS (10 mg. in 1 ml. for 0.5 hour) suggested an elevation of the immunological reaction to intravesical BCG. A strong binding capacity of PPS to the mammalian bladder wall was observed. In addition, and in contrast to bacteria commonly causing cystitis, a significant binding of PPS to mycobacteria was found: 3.5, 3.6 and 3.1 micrograms./ml. dry weight of BCG Connaught, RIVM and Pasteur, compared with 0.2, 0.3, 0.7 and 0.0 microgram./mg. dry weight of Escherichia coli, Streptococcus faecalis, Klebsiella pneumoniae and Proteus. The results suggest that PPS enhances the attachment of BCG to the bladder wall, resulting in an increased BCG-induced immunological reaction in the guinea pig. It may be speculated that pretreatment with PPS may increase the efficacy of BCG therapy in man, especially in those patients not exhibiting an immunological reaction.

Proteoglycans and glycosaminoglycans in tumor growth and migration: first experience with tumors of bladder and prostate origin

Proteoglycans (PGs), macromolecules that contain bound glycosaminoglycans (GAGs), are an abundant and ubiquitously distributed group of proteins with a large variety of heterogeneous structures. In recent years a whole range of functions, varying from structural/mechanical support to involvement in the regulation of cell proliferation and cell mobility, cell-cell interactions, and angiogenesis and modulation of the extracellular matrix, have been attributed to these compounds. In this communication an overview is presented dealing with the available knowledge of the (regulatory) properties of PGs and GAGs as participants in tumor growth and metastasis. Acquaintance with the biochemical, biophysical, and biological characteristics of PGs and GAGs may provide a rational basis of the therapeutic use of GAGs in the prevention of tumor growth and invasion. The scarcely available information related to the role of PGs and GAGs in uro-oncology and the potential application of GAGs in the treatment of urological tumors are discussed.

Altering the course of proliferative nephritides: the challenge of the 1990s

There is considerable evidence based on experimental pathology that heparin/heparinoids will benefit the course of the various forms of human proliferative nephritis. An alternative to heparin may be pentosan polysulphate. Another possibility is the infusion of prostaglandin E1 because of its anti-inflammatory and potentially antiproliferative actions. Both these approaches mimic natural pathophysiological control mechanisms.

Effect of pentosan, a novel cancer chemotherapeutic agent, on prostate cancer cell growth and motility

Pentosan is a new chemotherapeutic drug which is currently in Phase I clinical trials. In our experimental systems, in vivo, pentosan inhibits the growth of the highly metastatic MAT-LyLu (MLL) Dunning R3327 prostate cancer cell line only at toxic doses and has no apparent effect on growth in vitro. The mechanism of tumor inhibition of this drug is unknown; however, in vitro, pentosan exhibits a potent inhibition of cell motility. Cell motility is essential for tumor cell metastasis and angiogenesis. By blocking cell motility, pentosan has the potential to inhibit both tumor growth and metastasis. We have characterized the mechanism of motility inhibition by pentosan and believe it alters cell-extracellular matrix interactions. The mechanism of motility inhibition by pentosan appears to be independent of cytoskeletal structural alterations, including changes in microfilament and microtubule networks. Pentosan acts through a different mechanism than suramin, a drug which inhibits motility through inhibition of growth factor effects. In vitro, pentosan alters cellular contacts with the extravascular matrix and inhibits cell motility. In vivo, pentosan prolongs survival of rats injected with MLL cells by 25%, but did not appear to decrease the rate of primary tumor growth or the number of metastatic lesions in the treated animals. These data suggest that, in vivo, pentosan acts through an as yet undefined mechanism.