CD39/NTPDase-1 activity and expression in normal leukocytes

INTRODUCTION: CD39/NTPDase-1 is a cell surface enzyme expressed on leukocytes and endothelial cells that metabolizes ATP to ADP and AMP. CD39 is expressed on numerous different types of normal leukocytes, but details of its expression have not been determined previously. METHODS: We examined CD39 expression and activity in leukocytes isolated from healthy volunteers. Expression of CD39 on leukocytes was measured by FACS and activity of CD39 in lymphocytes and neutrophils was determined by an enzymatic radio-TLC assay. RESULTS: We established that CD39 is expressed on neutrophils, lymphocytes, and monocytes. The enzyme is found on >90% of monocytes, neutrophils, and B-lymphocytes, and 6% of T-lymphocytes and natural killer cells. Per cell density of expression varied, with the highest expression on monocytes and B-lymphocytes. ATPase and ADPase activities were highest on B-lymphocytes, lower on neutrophils, lowest on T-lymphocytes. The ratio of ADPase:ATPase activity was 1.8 for neutrophils and B-lymphocytes and 1.4 for T-lymphocytes. Hypertensive volunteers had lower levels of CD39 on their T-lymphocytes and NK cells. No correlation between age, gender, ethnic background, or cholesterol level and CD39 expression was observed. CONCLUSIONS: We conclude that CD39 activity and expression are present to varying degrees on all leukocytes types examined. Differences between leukocyte types should be considered when examining CD39 in disease states.     

Efficient targeted anticoagulant with active RGD motif

Three anticoagulants combining large peptide recombinant hirudin variants (rHV2-K47) and Arg-Gly-Asp (RGD) motif related to platelet aggregation were generated, i.e. sequences CRFPRGDADPYCE and CNPRGDFRCI were added to the C-terminus of hirudin to obtain RGD-hirudin 1 and 2, respectively, and the sequence RGDSE was inserted between residues 53-54 of hirudin to obtain RGD-hirudin 3. All products exhibited antithrombin and antiplatelet activities, especially IC50 of RGD-hirudin 1 and 2 were much lower with respect to previously reported similar peptides. Our data suggested that RGD-hirudin 1 and 2 would be promising anticoagulants in clinic. Moreover, the triangular structure of active RGD was shown by computer simulation, which might contribute to our understanding on integrin-related peptides and proteins.     

Dragon's Blood extract has antithrombotic properties, affecting platelet aggregation functions and anticoagulation activities

Ethnopharmacological relevance

Dragon's Blood from Dracaena cochinchinensis (Lour.) S.C. Chen (Yunnan, China), as a traditional Chinese medicinal herb, was shown to have certain antithrombotic effects. A new preparation process was used to extract effective components from Dragon's Blood. A 95% ethanol extract A (EA) and a precipitate B (PB) fraction were obtained and compared. Reliability of the preparation process was validated by pharmacodynamic experiments.

Materials and methods

A rat/mouse thrombosis and blood stasis model was developed for this study, and EA and PB effects on thrombosis, platelet functions and blood coagulation activities were analyzed.

Results

It was observed that the EA fraction had significantly better inhibitory effects than the PB fraction on thrombosis (p < 0.05), platelet aggregation function (p < 0.01) and anticoagulation activity (p < 0.05-0.01).

Conclusions

The results obtained here showed that EA fraction from Dragon's Blood contained pharmacologically effective compounds with antithrombotic effects, partially improving platelet function and anticoagulation activity.     

Platelet serotonin concentration and suicidal behavior in combat related posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is a serious and global problem, a psychiatric disorder that frequently occurs with different comorbidities, and is associated with a high suicide rate. Pathophysiologically, both PTSD and suicidal behavior are related to disturbances in the central serotonergic system. Serotonin (5-hydroxytryptamine, 5-HT) controls emotional behavior, anxiety, impulsivity and aggression, and nearly all known antidepressants and antianxiety drugs affect 5-HT transmission. Platelet 5-HT can be used as a limited peripheral marker of the central serotonergic synaptosomes, since it is related to particular basic psychopathological characteristics of several psychiatric disorders. Platelet 5-HT concentration has been reported to be similar in PTSD subjects and healthy controls, but suicidal patients across different psychiatric diagnoses have reduced platelet 5-HT concentration. This study examined platelet 5-HT concentration by the spectrofluorimetric method in male subjects: 73 suicidal and 47 non-suicidal veterans with current and chronic combat related PTSD, 45 suicidal and 30 non-suicidal comparative non-PTSD subjects and 147 healthy men. The presence of suicidal behavior (score=0, non-suicidal; scores > or =1, suicidal) was assessed with the Hamilton Depression Rating Scale-17 (HDRS). Platelet 5-HT concentration was significantly lower in suicidal PTSD and non-PTSD patients compared to non-suicidal patients or healthy controls. Since the majority of patients scored very low on item 3 of HDRS, no significant correlation between suicidal scores and platelet 5-HT concentration was found. These results show that reduced platelet 5-HT concentration is related to suicidal behavior in PTSD, and suggest that platelet 5-HT concentration might be used as a peripheral marker to predict suicidal behavior across psychiatric diagnoses.     

Platelet-rich plasma with keratinocytes and fibroblasts enhance healing of full-thickness wounds

Advances in tissue engineering led to the development of various tissue-engineered skin substitutes (TESS) for the treatment of skin injuries. The majority of the autologous TESS required lengthy and costly cell expansion process to fabricate. In this study, we determine the possibility of using a low density of human skin cells suspended in platelet-rich plasma (PRP)-enriched medium to promote the healing of full-thickness skin wounds. To achieve this, full-thickness wounds of size 1.767 cm² were created at the dorsum part of nude mice and treated with keratinocytes (2 × 10⁴ cells/cm²) and fibroblasts (3 × 10⁴ cells/cm²) suspended in 10% PRP-enriched medium. Wound examination was conducted weekly and the animals were euthanized after 2 weeks. Gross examination showed that re-epithelialization was fastest in the PRP+cells group at both day 7 and 14, followed by the PRP group and NT group receiving no treatment. Only the PRP+cells group achieved complete wound closure by 2 weeks. Epidermal layer was presence in the central region of the wound of the PRP+cells and PRP groups but absence in the NT group. Comparison between the PRP+cells and PRP groups showed that the PRP+cells-treated wound was more mature as indicated by the presence of thinner epidermis with single cell layer thick basal keratinocytes and less cellular dermis. In summary, the combination of low cell density and diluted PRP creates a synergistic effect which expedites the healing of full-thickness wounds. This combination has the potential to be developed as a rapid wound therapy via the direct application of freshly harvested skin cells in diluted PRP.     

Autologous i-PRF promotes healing of radiation-induced skin injury

Skin, as an exposed tissue, often suffers damage after exposure to radiotherapy and accidental events, which may lead to the formation of chronic refractory wounds. However, effective treatment options are usually limited for severe radiation-induced skin injury (RSI). Platelet-rich plasma (PRP) has been identified to promote wound healing, but whether a new generation of blood-derived biomaterial, injectable platelet-rich fibrin (i-PRF), is effective in repairing RSI remains unclear. In this study, blood was drawn from humans and Sprague–Dawley rats to prepare PRP and i-PRF, and the regenerative functions of PRP and i-PRF were investigated by exposing the dorsal skin of SD rats to local radiation (45 Gy) and exposing HDF-α cells and human umbilical vein endothelial cells (HUVECs) cells to X-rays (10 Gy). The healing effect of i-PRF on RSI was analysed by tube formation assay, cell migration and apoptosis assays, ROS assay, wound healing assay, histological characterisation and immunostaining. The results showed that exposure to high doses of radiation reduced cell viability, increased ROS levels and induced cell apoptosis, thereby causing dorsal trauma of rats. However, both PRP and i-PRF could resisted RSI, and they were capable of reducing inflammation and promoting angiogenesis and vascular regeneration. i-PRF has a higher concentration of platelets and platelet-derived growth factors, which has a more convenient preparation method and better repair effect and possesses a good application prospect for the repair of RSI.     

氩激光治疗糖尿病视网膜病变疗效评价

目的 探讨糖尿病视网膜病变氩激光治疗的远期效果。方法 根据眼底荧光血管造影(FFA)的结果，用氩激光全视网膜光凝术治疗DR患者87例(122只眼)，观察其视力、眼底、FFA，随访6个月-2年。结果 视力增进50只眼(40．98％)，视力无变化55只眼(45．08％)，视力下降17只眼(13．94％)，黄斑水肿消退及部分消退46只眼(82．14％)，带补充光凝34只眼。结论 氩激光视网膜光凝术是治疗DR的有效手段。对DR患者应早发现，根据不同病变类型选择合理的激光参数，确保高比例的有效光斑，以阻止病情恶化，保护视功能。