Cartilage restoration in haemophilia: advanced therapies.

Current treatment of joint cartilage lesions is based either on conventional techniques (bone marrow stimulation, osteochondral autograft or allograft transplantation) or on newly developed techniques (chondrocyte implantation and those based on cell therapy that use bioreactors, growth factors, mesenchymal stem cells [MSCs] and genetically modified cells). The aim of this article is to review the therapeutic strategies above mentioned and to determine whether the chondral damage seen in haemophilia could benefit from any of them. The different conventional techniques have shown similar results whereas autologous chondrocyte implantation, which is in common use at the present time, has not been shown to produce any conclusive results or to lead to the formation of hyaline cartilage. MSCs hold promise for the repair of joint cartilage given their differentiation capacity and the therapeutic effect. The use of bioreactors and growth factors, which stimulate cartilage formation, may optimize such strategies in the context of reimplantation of chondrocytes, differentiated MSCs and cartilage progenitor cells. The aim of cell therapy is restoration of function through the repair of damaged tissue or the stimulation of growth factor synthesis. Implantation of autologous chondrocytes or MSCs was up to now able to address only highly localized chondral lesions. Adequate control of the differentiation process as well as the use of growth factors and appropriate bioreactors could transform cell-based therapies into a more efficient and longer term treatment even for patients with haemophilia. Nevertheless, raising false expectations in these patients should be avoided. There are a number of approaches to cartilage restoration in haemophilic arthropathy, which are currently being explored for other joint related degenerative disorders. If it can be proven to be effective for the disorders in which clinical trials are ongoing and costs could be limited, it might be an useful palliative approach to haemophilic arthropathy. However, we still have a long way to go for use in haemophilic arthropathy.

Gene therapy for haemophilia...yes, but...with non-viral vectors?

High-purity plasma-derived and recombinant factors are currently safe and efficient treatment for haemophilia. The mid-term future of haemophilia treatment will involve the use of modified recombinant factors to achieve advantages such as decreased immunogenicity in inhibitor formation and enhanced efficacy as a result of their longer half-life. In the long-term, gene therapy and cell therapy strategies will have to be considered. Achievements in cell therapy to date have been using embryonic stem cells and hepatic sinusoidal endothelial cells. Current gene therapy strategies for haemophilia are based on gene transfer using adeno-associated viruses and non-viral vectors. Gene therapy for haemophilia is justified because it is a chronic disease and because a very regular factor infusion is required that may involve fatal risks and because it is very expensive. Haemophilia is a very good candidate for use of gene therapy protocols because it is a monogenic disease, and even low expression is able to achieve reversion from a severe to a moderate phenotype. The current trends in haemophilia using adeno-associated viral vectors are safe but also involve immunogenicity problems. The other alternatives are non-viral vectors. There have been in recent years relevant advances in non-viral transfection that raise hope for considering this possibility. Several research groups are opting for this experimental alternative. An expression over 5%, representing a moderate phenotype, for a few months with a high safety, regarding vector, transfected cells, and implantation procedure, would already be a great success. This may represent an intermediate protocol in which the expression levels and times obtained are lower and shorter respectively as compared to viral vectors, but which provide a potential greater patient safety. This may more readily win acceptance among both patients and haematologists because fatal events in the past due to HIV/HCV infection may constrain the implementation of viruses as vectors.

Salvage and interconversion of purines in developing Artemia.

Incorporation of the radiolabelled purine bases adenine, guanine and hypoxanthine into acid soluble fraction, RNA and DNA nucleotides during the early larval development of Artemia sp. was studied. Adenine was the best precursor and guanine the poorest. The adenine phosphoribosyltransferase (APRT) activity was considerably higher than that of hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and these activities did not significantly change throughout larval development. The pattern of purine interconversion was dependent on naupliar age. Conversion of [14C]adenine and [14C]hypoxanthine into guanine nucleotides increased with time of development. However, the conversion of [14C]guanine into [14C]adenine nucleotides was very low.

Presence, preliminary properties and partial purification of 5-phosphoribosylpyrophosphate amidotransferase from Artemia sp.

5'-Phosphoribosylpyrophosphate amidotransferase, which catalyzes the synthesis of phosphoribosylamine in the de novo synthesis of purine nucleotides, has been detected and partially purified approx. 800-fold from Artemia sp. nauplii. The apparent Km values for 5'-phosphoribosyl 1-pyrophosphate as substrate were 0.7 mM and 0.4 mM in the presence of glutamine and ammonia as nitrogenous sources, respectively, and the enzymatic activity was inhibited by purine 5'-ribonucleotide compounds and 5', 5'''-p1, p4-diguanosine tetraphosphate.

Reduced carnitine palmitoyl transferase activity and altered acyl-trafficking in red blood cells from hemodialysis patients.

We measured carnitine palmitoyl transferase activity, free carnitine, and long chain acyl carnitine levels in erythrocytes from 15 uremic patients and 25 controls. Carnitine palmitoyl transferase levels in patients were significantly lower than in controls. The levels of free carnitine and long chain acyl carnitines as well as the long chain acyl carnitine/free carnitine ratio were significantly higher in patients than in controls. Our results suggest that hemodialysis causes alteration in the acyl-trafficking in red blood cells membrane.

De novo biosynthesis and base composition of total and ribosomal ribonucleic acids during early development in Artemia sp.

De novo synthesis of total and ribosomal ribonucleic acids has been studied during the early stages of Artemia sp. development. By in vivo incorporation studies of [14C]HCO3- an increase has been found in both total and ribosomal RNA synthesis post hatching, with a similar distribution of radioactivity and base composition.

Protein tyrosine phosphatase activity modulation by endothelin-1 in rabbit platelets.

Protein tyrosine phosphorylation, modulated by the rate of both protein tyrosine kinase and protein tyrosine phosphatase activities, is critical for cellular signal transduction cascades. We report that endothelin-1 stimulation of rabbit platelets resulted in a dose- and time-dependent tyrosine phosphorylation of four groups of proteins in the molecular mass ranges of 50, 60, 70-100 and 100-200 kDa and that one of these corresponds to focal adhesion kinase. This effect is also related to the approximately 60% decrease in protein tyrosine phosphatase activity. Moreover, this inhibited activity was less sensitive to orthovanadate. In the presence of forskolin that increases the cAMP level a dose-dependent inhibition of the endothelin-stimulated tyrosine phosphorylation of different protein substrates and a correlation with an increase in the protein tyrosine phosphatase activity (11.6-fold compared to control) have been found. Further studies by immunoblotting of immunoprecipitated soluble fraction with anti-protein tyrosine phosphatase-1C from endothelin-stimulated platelets have demonstrated that the tyrosine phosphorylation of platelet protein tyrosine phosphatase-1C is correlated with the decrease in its phosphatase activity. As a consequence, modulation and regulation by endothelin-1 in rabbit platelets can be proposed through a cAMP-dependent pathway and a tyrosine phosphorylation process that may affect some relevant proteins such as focal adhesion kinase.

Effects of L-carnitine on erythrocyte acyl-CoA, free CoA, and glycerophospholipid acyltransferase in uremia.

We studied the effects of L-carnitine treatment in the acyl flux of erythrocyte membranes from uremic patients. We found a significantly lower relative proportion of long-chain acyl-CoA (LCCoA) to free CoA (FCoA) in patients than in control subjects. In addition, patients had reduced activities of both carnitine palmitoyltransferase (CPT) and glycerophospholipid acyltransferase (LAT; CoA dependent), and increased ratios of long-chain acylcarnitine (LCAC) to free carnitine in their erythrocytes. These data support the hypothesis that acyl-trafficking is altered in erythrocytes in uremia. After treatment with L-carnitine, we observed a significant increase in CPT and LAT activities as well as in the LCCoA-FCoA ratio, and a significant decrease in the ratio of LCAC to free carnitine. These results support the conclusion that L-carnitine supplementation improves erythrocyte flux in uremic patients.

Effect of adrenalectomy and glucocorticoid treatment on the levels of an insulin-sensitive glycosyl-phosphatidylinositol in isolated rat hepatocytes.

Insulin resistance caused by dexamethasone administration to rats was accompanied by a marked decrease in the hepatocyte content of an insulin-sensitive glycosyl-phosphatidylinositol, as well as by a blockade of its hydrolysis in response to this hormone. In contrast, bilateral adrenalectomy provoked a significant increase of the cellular glycosyl-phosphatidylinositol levels. Under all the assayed metabolic conditions, a close direct correlation was established between the basal content of this compound and the number of insulin receptors present in the isolated hepatocytes.

A simple and rapid experimental protocol for studies of nucleic acids metabolism and their base composition.

A suitable, simple and rapid protocol for metabolic studies of nucleic acids and determining their base composition, using reversed-phase high-performance liquid chromatography is described. Modified classic methods of isolation of the nucleic acids fraction from a biological material, in our particular case Artemia sp., were used. Then analysis of their constituents and the incorporated radioactivity, after hydrolytic processes, was performed by high-performance liquid chromatography under isocratic conditions, with 9 min total retention time. This method may be applied in several aspects of nucleic acids research, such as molecular cloning or metabolic and phylogenetic studies.

A rapid reliable method to use specific probes labelling polymerase chain reaction (PCR) products.

Polymerase chain reaction (PCR) has allowed highly sensitive detection and amplification of individual DNA sequences. To generate specific probes for genes or cDNAs that have not yet been cloned, it is often necessary to label PCR products which are then used in Southern or Northern hybridizations or for screening cDNA and genomic DNA libraries. In this paper a rapid and versatile method of using PCR products, as specific probes, is described, after digestion with EcoRI in buffer H, in the presence of PCR reaction buffer, and purification of the PCR products for avoid the interference by competition of unlabelled dCTP in the directionally random labelling.

[Reduced neuronal nitric oxide synthetase and c-protein kinase levels in Alzheimer's disease]. / Disminución de los niveles de óxido nítrico sintasa y proteína quinasa C neuronales en la enfermedad de Alzheimer.

INTRODUCTION: Alzheimer's disease is characterized by a general and progressive dementia and by the presence of beta-amiloide deposits. OBJECTIVE: The levels of neuronal nitric oxide synthase (NOS) and protein kinase C (PKC), and the relationship between these proteins, the free-radical theory and the high level of beta-amiloide in Alzheimer's disease, have been studied. MATERIAL AND METHODS: The study has been performed in samples of Alzheimer's disease (superior, medial and inferior regions of temporalis gyrus) from control individuals and patients. The tissue was homogenized and the proteins were analyzed using monoclonal antibodies for NOS and PKC. RESULTS: Lower levels of neuronal constitutive NOS (37% +/- 2.5 and 52% +/- 3.0) in Alzheimer's disease derived superior and inferior temporalis gyrus, respectively, were observed. No changes were found in superior temporalis gyrus in PKC isoforms levels, involved in the processing for the beta-amiloide precursor protein. In the medial and inferior regions the PKC level was 5% +/- 0.5 to 22% +/- 3.0. CONCLUSIONS: These results could be related with an imbalance in the superoxide/nitric oxide ratio as a consequence of the non-inhibition of lipoxygenase, and with a neurotransmission dysfunction due, all this, to the decrease of nitric oxide levels. On the other hand, a relationship could be proposed between the high concentrations of beta-amiloide and the decrease in PKC levels in Alzheimer's disease.

Induced human pluripotent stem cells and advanced therapies: future perspectives for the treatment of haemophilia?

Human induced pluripotent stem cells (iPSCs) have revolutionized the stem cell field. These iPSCs from somatic cells have been reprogrammed with the introduction of transcription factors and are capable to differentiate into cells from all three germ layers. These strategies require retrovirus transduction or transfection of plasmid vectors strategy without viral transduction. Another promising strategy is based on direct delivery of the reprogramming proteins, addition of signal transduction inhibitors and chemical promoter cell survival. The main advantages of iPSCs cells are that they have not included in the debate over the ethics of embryonic stem cell. Current therapy of haemophilia is based on factor VIII (FVIII) or factor IX (FIX) replacement therapy including prophylactic or demand protocols of fixed-dose, and as future alternative, gene and cell therapy. Gene therapy can be made by using viral vectors, mainly lentiviral (LVV) and adeno-associated viruses (AAV) in adult stem cells and autologous fibroblasts, platelets or haematopoietic stem cells, and transfer using non-viral vectors (NVV). Cell therapy for haemophilia is based, mainly, in transplantation of healthy cells to replace the deficient function, for example, the transplantation of liver sinusoidal endothelial cells or endothelial progenitor cells derived from iPSCs. Recently, as first time in haemophilia, endothelial progenitor cells derived from iPSCs cells express FVIII protein effectively, engraft within the hepatic parenchyma, and functionally integrate to provide the therapeutic benefit for a phenotypic correction in haemophilia. Advanced therapies, gene and cell therapy and tissue engineering or iPSCs technology, can provide a potential clinical application in the treatment of haemophilia and other monogenic disorders. Because to date there are not relevant results for phenotypic correction in haemophilia, iPSCs technology could represent a potential alternative based on cellular therapy.

Gene therapy for haemophilia: the end of a 'royal pathology' in the third millennium?

Haemophilia is an ideal condition for gene therapy because of its monogenetic character and the fact that it requires only a small amount of the expressed protein to achieve palliation. To date, research in the field of gene therapy for haemophilia has largely relied on retroviruses, adenoviruses and adeno-associated viruses as transfer vectors and the major aims will be to achieve stable longlasting in vivo expression of factors VIII or IX (FVIII or FIX) at therapeutic levels. Two clinical trials have been approved by the US Food and Drug Administration (FDA), using miniadenovirus FVIII and the intrahepatic and intramuscular delivery of adeno-associated virus FIX. In the third millennium, haemophilia treatment should encompass more ambitious goals through gene replacement, to result in permanent and safe haemophilia 'eradication', making haemophilia a part of the history of medicine.

Separation of major RNA-derived nucleotides by reversed-phase liquid chromatography.

The effects of pH, ionic strength and amount of methanol in the eluent on the retention of 5'-, 3'- and 2'-ribonucleoside monophosphates on a reversed-phase high-performance liquid chromatographic system are described. The data were used to develop suitable separation protocols for synthetic nucleotide mixtures and applied to the separation of RNA nucleotides derived by alkaline hydrolysis.

A set of procedures for resolving purine compounds by reversed-phase high performance liquid chromatography: application to the study of purine nucleotide and nucleic acid metabolism.

A set of simple procedures for the separation of major purine 5'-ribonucleotides including diguanosine polyphosphates, purine and pyrimidine bases, and 2'- and 3'-nucleotide monophosphates using reversed-phase high-performance liquid chromatography and isocratic elution study of purine nucleotide and nucleic acid biosynthesis in Artemia is presented.