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Biomedical subjects

M J Seghatchian

Publications and source records attributed to M J Seghatchian.

At least 19 recordsLinked to original sources
PubMed2000

Cytokine accumulation in stored red cell concentrates: effect of buffy-coat removal and leucoreduction.

The accumulation of cytokines in stored red blood cell concentrates (RCCs) has been implicated as a potential cause of transfusion reactions associated with the use of such products. At present, it is unclear whether there is any link between residual leukocyte and/or platelet content with cytokine levels in various RCCs. In this study, we have therefore assessed cytokine levels of leukocyte (e.g., IL8) and platelet (e.g., RANTES, TGF-beta1) origin in supernatants of RCCs prepared by the plasma reduced method or by depletion of the buffy coat. We have also assessed whether the Duffy antigen receptor (DARC, a promiscuous receptor for some chemokines) has any role in the diminution of cytokine levels in stored blood components by comparing cytokine levels in stored plasma reduced RCCs derived from both DARC +ve and DARC -ve individuals. In addition, comparison of filtered and non-filtered products of the same origin has also been conducted. Results showed that supernatants from DARC -ve concentrates contained higher levels of IL-8 up to days 14/15 of storage compared with DARC +ve RCCs. However, at later time points, similar levels of IL-8 were observed in RCCs regardless of their Duffy receptor status. For TGF-beta1 and RANTES, no significant difference in the levels of these cytokines was detected between DARC +ve and DARC -ve concentrates. Removal of leukocytes and platelets by conventional leukocyte filtration significantly reduced the accumulation of cytokines. Buffy coat reduced RCCs contained minimal amounts of IL-8 and TGF-beta1 but no RANTES. We conclude therefore, that the levels of cytokines in the supernatants of RCCs stored at 4 degrees C are related mainly to their leucocyte and platelet content.

Blood Preservation↗
PubMed2000

Cytokines in WBC-reduced apheresis PCs during storage: a comparison of two WBC-reduction methods.

BACKGROUND: Several studies have suggested that cytokine accumulation during storage of platelet concentrates (PCs) may mediate nonhemolytic febrile transfusion reactions and that a reduction in WBC numbers prevents the generation of cytokines. Despite efforts to minimize WBC contamination in apheresis PCs, high numbers of WBCs and increased cytokine levels may still occur, depending on the quality of the apheresis device employed. STUDY DESIGN AND METHODS: This study was undertaken to investigate whether PCs collected with WBC-reduction devices (Spectra LRS, COBE;or MCS+ LDP, Haemonetics) were sufficiently depleted of WBCs to limit cytokine accumulation during storage. The study evaluated 1) the levels of cytokines of WBC and platelet origin in two types of apheresis PCs during storage and 2) the effects of prestorage filtration on cytokine levels in the Spectra LRS PCs. RESULTS: In the Spectra LRS PCs, low levels of IL-6, IL-8, and monotype chemoattractant protein 1 (MCP-1) were detected in Day 1 PCs, and they remained consistent during the shelf life. RANTES, platelet factor 4 (PF4), beta-thromboglobulin (beta-TG), and transforming growth factor (TGF)-beta1 were also detected in these PCs, and their levels increased significantly on storage. Prestorage filtration of Spectra LRS PCs did not further reduce the levels of IL-6, IL-8, MCP-1, PF4, beta-TG, and TGF-beta1 in the filtered component. In the MCS+ LDP PCs, IL-6 was detected on Day 1, and its level increased significantly on storage, whereas the levels in the Spectra PCs remained steady. IL-8 levels were lower in MCS+ LDP PCs than in Spectra LRS PCs of the same age. MCP-1 levels were similar in both products on Day 1 and marginally increased in stored MCS+ LDP PCs. Substantial amounts of RANTES, PF4, beta-TG, and TGF-beta1 occurred in Day 1 MCS+ LDP PCs, and, on storage, these levels rose significantly. CONCLUSION: Despite a significant reduction in levels of WBC-derived cytokines, platelet-derived cytokines were present in different amounts in the two products.

Blood Platelets↗
PubMed1998

Update on leucocyte depletion of blood components by filtration.

It has long been recognized that allogenic leucocytes from donor blood are responsible for serious untoward effects in some transfused patients such as alloimmunization, febrile reactions, platelet refractoriness, transfusion associated acute lung injury, immunosuppression as well as transmission or reactivation of viruses such as CMV, HTLV or EBV. Leucocytes are also known to accelerate the rate of storage lesion. The optimal method to remove leucocytes from blood components has been shown to be filtration. However, many variables exist in the properties of leuco-depletion filters (material, composition, surface charge, mechanisms of leucocyte entrapment), the blood components to be filtered (composition, age), and the filtration method (pre- or post-storage, priming and rinsing, temperature, flow rate). In this paper principles of filtration and subsequent logistic consequences will be discussed. It is recommended to carefully select a filter for a specific blood component and to perform leuco-depletion procedures under controlled conditions according to validated methods meeting Good Manufacturing Practice (GMP) and Good Laboratory Practice (GLP).

Blood Component Transfusion↗
PubMed1997

Cytokines in platelet concentrates: a comparison of apheresis platelet (haemonetics) and filtered and unfiltered pooled buffy-coat derived platelet concentrates.

Variable degrees of platelet activation, shape changes, microvesiculation and fragmentation may occur during collection, processing and storage of platelet concentrates (PCs), contributing to different rate of platelet storage lesion. Leukocytes contribute to both the frequency of transfusion reactions and the acceleration of the rate of platelet storage lesion hence leukocyte removal of platelet concentrates has been introduced to overcome these problems. However transfusion reaction can still occur with the use of leuko-reduced products and it is not fully elucidated that the rate of storage lesion is equivalent for filtered and unfiltered counter parts. This issue has been addressed in this manuscript comparing the generation of cytokines during storage in PCs derived from pooled buffy coat with the standard apheresis products, with a similar level of leukocyte contamination. The EDTA-induced shape change in platelet was used as an index of platelet functional integrity. In addition IL-8 and TGF beta were used as indicators of filtration process-inducing stimulation of cytokines. Our results clearly indicate that a rapid disc/spheric conversion occurs during storage of buffy-coat derived PC, and while prestorage filtration reduces both IL-8 content immediately after filtration and at the end of platelet shelf life but such a process may lead to slight enhancement of the rate of TGF beta generation indicating that any additional process may have some bearing in stimulation of TGF beta release.

Blood Platelets↗
PubMed1997

Effect of pH and buffering condition on dMPV of three types of platelet concentrates.

Normal platelets display a log normal size distribution pattern when analysed by an automated cell counter. Considerable changes in the platelet size distribution occurs during collection, processing and storage. This is easily monitored by the variation seen in the cellular indices or size distribution patterns. Platelet activation leads to a shift to the right whereas discoid/spheric conversion and microvesiculation/fragmentation are associated to shift to the left. Therefore changes in cellular indices are of value in assessing the dynamic shape changes and aggregation/disaggregation that platelet undergo during storage. We describe here an objective method for measuring platelet functional integrity based on cell counting. Our procedure is simple and based on the measurement of difference (d) of MPV before and after the addition of platelet samples to EDTA (4 ml dry dipotassium EDTA tube), incubating at 22 degrees C for a period of 1 h (for optimisation of shape changes and disaggregation) before counting. Since the platelet functional activity/aggregation states are pH-dependent we have investigated the effect of buffering condition on the functional integrity measured by dMPV. Both the standard and buffered EDTA exposure procedures appear to be suited for monitoring platelet functional integrity/aggregation and activation states but the standard EDTA protocol eliminates the need for pH determination hence is our preferred diagnostic tool, for platelet functional integrity and aggregation states.

Blood Platelets↗
PubMed1997

The quality of clinical FFP, cryoprecipitate and cryosupernatant derived from single donor apheresis procedures and random donations collected in a BAT system: assessment of the activity states of FVIII, contact activation, microvesicle content and cytokines.

In establishing the best practice and/or evaluating any new process or procedures it is essential that apart from the compliance to specification, provided by the Guidelines (i.e. AABB or UK-BTS/ NIBSC), the changes that might occur in the activation states, and other regulatory mechanisms should be considered. Of particular relevance are the changes in the levels of FVIII in relation to its carrier protein and stabiliser von Willebrand factor; the levels of contact activation and serine proteases and the level of cellular fragmentation/microvesiculation due to shear induced stress in the cellular contents of blood and the development of cytokines. This brief original report compares the above parameters for three types of FFP, cryoprecipitate and the cryosupernatant in respect to same new in house quality monitoring criteria of acceptability.

Blood Donors↗
PubMed1997

Stem cells: what's happening? Current concepts and recent advances.

Allogeneic haemopoietic stem cells, as alternative to bone marrow transplantation and platelet therapy remains the focus of the current area of research/development in transfusion science/medicine. This brief progress report on "Stem Cells: What's Happening?" is focused on the advances and some unresolved problems associated with cellular therapy and haemopoietic progenitor cells from various sources.

Bone Marrow Transplantation↗
PubMed1997

Effect of cold exposure on platelet concentrates: changes in platelet indices and aggregation states.

Samples from platelet concentrates (filtered/non-filtrated, at the beginning/the end of shelf life) were exposed to 4 degrees C overnight, subsequent to dilution in platelet storage media (PSM) and/or exposure to EDTA to induce shape changes. Paired sampling protocol (+/- EDTA) was used and changes in cellular indices and induced-aggregation states were measured by Technicon H*1. Cold induced changes in platelets as identified by increase in MPV (0.5-0.8 fL for EDTA; 1.5-2.0 fL for citrated samples) with concomitant reverse changes in PDW ranging from 2-13 per cent was observed. Processing, storage and cold exposure also induced disparity between leucocyte peroxidase/basophil counts. This in conjunction with changes in platelet counts and cellular indices upon exposure to EDTA provide a unique new tool for assessing the aggregation states of platelets during processing and storage. Both filtration and dilution in PSM affect platelet storage stability. Platelets which have already undergone shape changes (i.e. exposure to EDTA) responded to a lesser degree to cold exposure. Our findings indicate that platelets's response to cold exposure can be used as a simple, reliable and accurate test for assessment of platelet morphological and function integrities.

Blood Preservation↗