Traitement par PRP 1 partie : les lésions cartilagineuses et musculaires

Background

The frequency and diversity of injuries affecting the musculoskeletal system have incited much research leading to the discovery of new treatment options including Platelet-Rich Plasma (PRP) therapy. To date, indications have been extended to injuries involving several types of tissues including cartilage and muscles.

Method

We searched the English and French literature for articles reporting a high level of proof on PRP therapy for cartilage or muscle injuries. We found six articles on cartilage lesions and three on muscle lesions.

Results

For cartilage lesions, PRP provides superior results compared with hyaluronic acid for early stage injuries, but the evidence is limited to a short follow-up (maximum 6 months). For muscle lesions, the PRP results are encouraging.

Conclusion

As long as a consensus has not been reached concerning the methods applied for preparing PRP, the concentrations used, the activation method, and the formulation, it will be difficult to compare studies, despite their high level of proof, and to affirm that PRP has a beneficial effect on repair of different body tissues. Use of PRP therapy for cartilage injury is now a validated option for pain relief, especially in young patients after failure of hyaluronic acid. The delay of action is long (at least 6 months). Injection formulations are easy to use, well tolerated and safe. Cost is relatively low.     

A new sensitive microplate assay of plasma endotoxin.

We have developed a microplate method for determining endotoxin in platelet-rich plasma-using Endospecy, an endotoxin-specific chromogenic Limulus test reagent. Nonspecific activators and inhibitors of the test were eliminated by exposing samples (5 microliters) to the alkali reagent consisting of KOH, CaCl2, Triton X-100, ethyleniminepolymer and N,N-bis(2-hydroxyethyl)glycine. The recoveries of various endotoxins were almost complete and not enhanced by dilution. The dose-response curve was linear over endotoxin concentrations of 2-400 pg/ml with good precision (C.V. less than 5.0%). Normal human plasmas (n = 30) contained less than 5.0 pg/ml of endotoxin in reference to that of Escherichia coli 0111: B4. All plasma samples with high concentration of endotoxin by a conventional method showed high values by the microplate assay as well. Since it does not require centrifugation, the new treatment allows the whole reactions to proceed on the same microplate. This permits us to apply the Limulus test to an automated assay system, making plasma endotoxin determination simpler and more rapid than a conventional test tube method.     

The major histocompatibility complex of the cynomolgus monkey: absorption analysis of 24 CyLA antisera

The major histocompatibility complex (MHC) of the cynomolgus monkey consists of at least 35 serologically defined specificities, 14 of which have been assigned to the CyLA-A locus, 10 to the B locus, and six to the newly identified C locus. Selected specificities and antisera were further studied by the analysis of data obtained from absorptions with single donor platelets of known CyLA type. These data confirmed the existence of four groups of cross-reactive specificities identified by serological typing and revealed that three other well-defined specificities could be divided into two or more subtypes. Seven sera were shown to contain two or more populations of distinct, probably noncross-reactive antibodies that could be readily separated by absorption. Of the 24 sera analyzed, only three could be considered likely to contain antibodies reactive with a single CyLA specificity. At least three antibody specificities, after repeated absorption attempts, could not be readily removed by platelets and may reflect poor expression of the determinants on the platelet membrane. The complexity and degree of polymorphism of the CyLA system approaches that known for the human HLA complex. This homology of genetic organization and serologic features provide additional evidence in yet another species for the important role that these systems of alloantigens play in the organism.     

Inhibition of bovine platelet function by T-2 toxin, HT-2 toxin, diacetoxyscirpenol and deoxynivalenol

The aggregation of bovine platelets suspended in homologous plasma is inhibited in the presence of T-2 toxin, HT-2 toxin, diacetoxyscirpenol (DAS) or deoxynivalenol (DON) when either collagen or ADP is used as the stimulatory agent for aggregation. For each of the mycotoxins the degree of inhibition is dependent on the amount of trichothecene present in the platelet suspension but is not dependent on the time of exposure of the platelets to the toxin. For both ADP- and collagen-stimulated platelets, the order of potency of inhibition is T-2 toxin greater than HT-2 toxin greater than DAS greater than DON. A significant (P less than 0.01) dose-dependent decrease was also observed in the amount of the thromboxane B2 released from collagen-stimulated platelets in the presence of each of the mycotoxins.     

L-amino acid oxidase from Vipera lebetina venom: isolation, characterization, effects on platelets and bacteria.

The L-amino acid oxidase from Vipera lebetina venom was purified to homogeneity using combination of size exclusion, ion exchange and hydrophobic chromatography. The monomeric molecular mass of the homodimeric enzyme is 60.9kDa. The N-terminal and the tryptic peptides share high homology with other snake venom L-amino acid oxidases. The enzyme displays high specificity towards hydrophobic L-amino acids, the best substrates are L-Met, L-Trp, L-Leu followed by L-His, L-Phe, L-Arg and L-Ile. Six substrates-Gly, L-Ser, L-Thr, L-Pro, L-Cys, L-Asp--were not oxidized. The enzyme has antimicrobial activity inhibiting the growth of both Gram-negative and Gram-positive bacteria. V. lebetina LAAO dose-dependently inhibited platelet aggregation induced by ADP or collagen. In case of ADP-induced aggregation the inhibitory effect was more pronounced on the second wave of aggregation.     

Effect of thio reagents on platelet transport processes and responses to stimuli

N-ethylmaleimide at submillimolar concentrations inhibited platelet aggregation and shape-change induced by ADP, collagen-induced aggregation, and the active transport of adenosine (but not of adenine or serotonin). p-Chloromercuribenzene sulphonate had broadly similar activity but was much less potent, lodoacetate, which at 0.3 mM caused leakage of ³H from the cytoplasm of platelets prelabelled with [³'H]adenine, had no inhibitory effects at lower concentrations, and 5'5'-dithio-bisnitrobenzoic acid was inactive up to 3 mM. Dithiothreitol. which slightly inhibited aggregation at 0.5 mM, induced aggregation directly at concentrations above 1 mM. and 2-amino(4-isothioureylmethyl-ene)-thiazol di HCl was a potent and selective inhibitor of serotonin transport, and also inhibited collagen-induced aggregation. Ecto-SH groups are apparently not involved in regulating platelet active transport processes or responses to stimuli, but intracellular thio groups are important in platelet secretion, aggregation, and shape-change, and also in the transport of serotonin and adenosine, but not of adenine.     

富含血小板血浆双相接种法构建组织工程骨

目的：传统的细胞接种法接种效率低,影响组织工程骨的成骨质量。本研究预探讨富含血小板血浆双相接种法是否可以提高细胞接种效率、优化组织工程骨的构建。方法：分别用富含血小板血浆、乏血小板血浆重悬BMSCs,灌注于三维多孔PLGA支架中,凝血酶促凝,体外培养。通过扫描电镜观察支架表面的细胞分布;通过检测支架内DNA含量、ALP含量、成骨基因表达情况分析细胞的接种效率、增殖和分化情况,并与传统的接种方法进行比较。结果：富含血小板血浆和乏血小板血浆双相接种法均能提高细胞与三维支架的结合效率;富含血小板血浆还可以促进支架内细胞的增殖,同时不影响细胞的分化。结论：双相接种法可以提高细胞的接种效率;与普通双相接种法相比,富含血小板血浆双相接种法可以进一步优化组织工程骨的构建。     

Effects of additional treatment of sarpogrelate to aspirin therapy on platelet aggregation and plasma plasminogen activator inhibitor activity in patients with stable effort angina

Introduction

Serotonin is secreted from platelets at sites of endothelial injury, where it promotes thrombogenic reactions. Serotonin is reported to be associated with not only coronary artery disease but also cardiac events.

Materials and Methods

We studied 33 patients with stable effort angina (SEA) (11 patients with multivessel disease (MVD) and 22 patients with singlevessel disease (SVD)) and 25 patients with chest pain syndrome (CPS). Sarpogrelate was administered to 22 of 33 patients with SEA in addition to aspirin therapy, and platelet aggregation, plasma serotonin concentration, and plasma plasminogen activator inhibitor (PAI) activity were measured before and 1 week after administration.

Results and Conclusions

Serotonin level was higher in patients with MVD than in those with SVD (p < 0.05) and in those with CPS (p < 0.001). The formation of small-sized platelet aggregates was significantly higher in the high serotonin group than in the low serotonin group of SEA patients. The formation of large-sized platelet aggregates was significantly decreased by administration of sarpogrelate (P < 0.05). The formation of small- or medium-sized aggregates was not significantly decreased. Plasma PAI activity decreased significantly (P < 0.05) although the plasma serotonin concentration did not show significant change by administration of sarpogrelate. Plasma serotonin level is increased in relation to severity of coronary artery disease and plasma serotonin level is associated with increased platelet aggregation. Administration of sarpogrelate in addition to aspirin therapy reduces the increased platelet aggregation and PAI activity, and it may indicate that additional administration of sarpogrelate is useful for patients with SEA.     

Genetic determinants of response to aspirin: appraisal of 4 candidate genes

Introduction

Intersubject variability in platelet response to aspirin could be related to genetic factors that regulate platelet enzymes or receptors. This study evaluates the impact of the selected polymorphisms in the COX-1 gene, the CYP5A1 gene, the P2RY1 receptor gene, and the GPIIbIIIa receptor gene on platelet response to aspirin and risk of suffering from major adverse cardiovascular and cerebrovascular events (MACCE).

Materials and methods

192 Caucasian patients with stable coronary artery disease treated with daily aspirin were recruited and followed for 3 years. Platelet aggregation was measured by light transmission aggregometry with arachidonic acid (1.6 mM) and adenosine diphosphate (5, 10 or 20 μM) used as agonists. Genotyping was performed by standard PCR methods.

Results

Arachidonic acid-induced platelet aggregation was unaffected by the COX-1 22C/T and by the Pl^A1/A2 polymorphisms. However, carriers of the 1622 G/G genotype of the P2RY1 gene had significantly higher levels of arachidonic acid-induced platelet aggregation compared with non-carriers (AA 2.0%, AG 2.0% vs. GG 9.0%, p = 0.047). Carrying the 1622 G/G genotype increased the risk of inadequate platelet response to aspirin, defined as arachidonic acid-induced aggregation ≥ 20%, by a factor of 8.5 (1.4 - 53.3, p = 0.022) and the risk of 3-year MACCE by a factor of 7 (1.4 - 34.7, p = 0.017).

Conclusion

The 1622A/G mutation of the P2RY1 gene could contribute to inadequate platelet response to aspirin and is associated with an increased risk of suffering from MACCE.