Direct and indirect effects of climate change on distribution and community composition of macrophytes in lentic systems.

Macrophytes are an important part of freshwater ecosystems and they have direct and indirect roles in keeping the water clear and providing structure and habitats for other aquatic organisms. Currently, climate change is posing a major threat to macrophyte communities by altering the many drivers that determine macrophyte abundance and composition. We synthesise current literature to examine the direct effects of climate change (i.e. changes in CO2 , temperature, and precipitation patterns) on aquatic macrophytes in lakes as well as indirect effects via invasive species and nutrient dynamics. The combined effects of climate change are likely to lead to an increased abundance and distribution of emergent and floating species, and a decreased abundance and distribution of submerged macrophytes. In small shallow lakes, these processes are likely to be faster than in deep temperate lakes; with lower light levels, water level fluctuations and increases in temperature, the systems will become dominated by algae. In general, specialized macrophyte species in high-latitude and high-altitude areas will decrease in number while more competitive invasive species are likely to outcompete native species. Given that the majority of endemic species reside in tropical lakes, climate change, together with other anthropogenic pressures, might cause the extinction of a large number of endemic species. Lakes at higher altitudes in tropical areas could therefore potentially be a hotspot for future conservation efforts for protecting endemic macrophyte species. In response to a combination of climate-change induced threats, the macrophyte community might collapse, which will change the status of lakes and may initiate a negative feedback loop that will affect entire lake ecosystems.

Differential effect of drought regimes on the seedling performance of six floodplain grassland species.

The performance of seedlings is crucial for the survival and persistence of plant populations. Although drought frequently occurs in floodplains and can cause seedling mortality, studies on the effects of drought on seedlings of floodplain grasslands are scarce. We tested the hypotheses that drought reduces aboveground biomass, total biomass, plant height, number of leaves, leaf area and specific leaf area (SLA), and increases root biomass and root-mass fraction (RMF) and that seedlings from species of wet floodplain grasslands are more affected by drought than species of dry grasslands. In a greenhouse study, we exposed seedlings of three confamilial pairs of species (Pimpinella saxifraga, Selinum carvifolia, Veronica teucrium, Veronica maritima, Sanguisorba minor, Sanguisorba officinalis) to increasing drought treatments. Within each plant family, one species is characteristic of wet and one of dry floodplain grasslands, confamilial in order to avoid phylogenetic bias of the results. In accordance with our hypotheses, drought conditions reduced aboveground biomass, total biomass, plant height, number of leaves and leaf area. Contrary to our hypotheses, drought conditions increased SLA and decreased root biomass and RMF of seedlings. Beyond the effects of the families, the results were species-specific (V. maritima being the most sensitive species) and habitat-specific. Species indicative of wet floodplain grasslands appear to be more sensitive to drought than species indicative of dry grasslands. Because of species- and habitat-specific responses to reduced water availability, future drought periods due to climate change may severely affect some species from dry and wet habitats, while others may be unaffected.

Flooding tolerance of four floodplain meadow species depends on age.

Numerous restoration campaigns focused on re-establishing species-rich floodplain meadows of Central Europe, whose species composition is essentially controlled by regular flooding. Climate change predictions expect strong alterations on the discharge regime of Europe's large rivers with little-known consequences on floodplain meadow plants. In this study, we aim to determine the effects of flooding on seedlings of different ages of four typical flood meadow species. To this end, we flooded seedlings of two familial pairs of flood meadow species of wetter and dryer microhabitats for 2 weeks each, starting 2, 4, 6, and 8 weeks after seedling germination, respectively. We show that a 2-week-flooding treatment had a negative effect on performance of seedlings younger than 6 weeks. Summer floods with high floodwater temperatures may have especially detrimental effects on seedlings, which is corroborated by previous findings. As expected, the plants from wet floodplain meadow microhabitats coped better with the flooding treatment than those from dryer microhabitats. In conclusion, our results suggest that restoration measures may perform more successfully if seedlings of restored species are older than the critical age of about 6 weeks before a spring flooding begins. Seasonal flow patterns may influence vegetation dynamics of floodplain meadows and should, therefore, be taken into account when timing future restoration campaigns.

Change of the metabolomic profile during short-term mononuclear cell storage.

BACKGROUND AND OBJECTIVES: Short-term storage of leukapheresis products used for immunotherapeutic mononuclear cell (MNC) products is a frequent event. The analysis of time-related metabolic patterns enables the characterization of storage-related effects in MNCs and the hypothesis-based optimization of the MNC medium. MATERIALS AND METHODS: The MNC products from seven leukapheresis procedures were stored within a closed bag system for 48 h. Concentrations of amino acids, biogenic amines, phospho- and sphingolipids and hexoses in the medium were measured by targeted metabolomics. The viability of MNC subpopulations was assayed by Annexin V (AnV) and JC-1 staining. RESULTS: Glucose depletion and a significant change of the acylcarnitine profile are early events within the first 24 h of storage. In contrast, for most amino acids, the maximum increase was observed at 48 h of storage as mirrored by an increase in the amino acid levels by a mean factor of 1·2 (1·3, 2·0) after 6 h (24 h, 48 h, respectively). This was except for the concentrations of glutamine and lysine, which did not change significantly. The taurine concentration showed a twofold increase within the first 24 h and remained constant thereafter. The steepest increase in AnV+ and 7-AAD+ CD4+ T cells was found between 24 and 48 h. CONCLUSION: The time-course of apoptosis and metabolic patterns in the MNC products demonstrate that 24 h of storage is a decisive time-point, as afterwards key metabolic pathways showed nonlinear detrimental changes. Optimization of storage by supplementation of specific substrates demands therefore an early intervention.

Clonality increases with snow depth in the arctic dwarf shrub Empetrum hermaphroditum.

PREMISE OF THE STUDY: Vegetative reproduction and spread through clonal growth plays an important role in arctic-alpine ecosystems with short cool growing seasons. Local variation in winter snow accumulation leads to discrete habitat types that may provide divergent conditions for sexual and vegetative reproduction. Therefore, we studied variation in clonal structure of a dominant, evergreen, dwarf shrub (Empetrum nigrum s.l. with the two taxa E. nigrum L. s.s. and E. hermaphroditum Hagerup) along a snow cover gradient and compared clonal diversity and spatial genetic structure between habitats. METHODS: We studied 374 individual shoots using 105 polymorphic AFLP markers and analyses based on hierarchical clustering, clonal diversity indices, and small-scale spatial genetic structure with pairwise kinship coefficient. We used two approaches to define a threshold of genotypic distance between two samples that are considered the same clone. Clonality was examined among three habitats (exposed ridges, sheltered depressions, birch forest) differing in snow conditions replicated in four study regions in Norway and Sweden. KEY RESULTS: Clonality of E. hermaphroditum differed between habitats with an increase in clonal diversity with decreasing snow depth. Small-scale spatial genetic structure increased with decreasing clonal diversity and increasing clone size. In three study regions, E. hermaphroditum was the only species, whereas in one region E. nigrum also occurred, largely confined to exposed ridges. CONCLUSIONS: Our results demonstrated that snow cover in conjunction with associated habitat conditions plays an important role for the mode of propagation of the dwarf shrub E. hermaphroditum.

AM fungal communities inhabiting the roots of submerged aquatic plant Lobelia dortmanna are diverse and include a high proportion of novel taxa.

While the arbuscular mycorrhizal (AM) symbiosis is known to be widespread in terrestrial ecosystems, there is growing evidence that aquatic plants also form the symbiosis. It has been suggested that symbiosis with AM fungi may represent an important adaptation for isoëtid plants growing on nutrient-poor sediments in oligotrophic lakes. In this study, we address AM fungal root colonization intensity, richness and community composition (based on small subunit (SSU) ribosomal RNA (rRNA) gene sequencing) in five populations of the isoëtid plant species Lobelia dortmanna inhabiting oligotrophic lakes in Southern Sweden. We found that the roots of L. dortmanna hosted rich AM fungal communities and about 15 % of the detected molecular taxa were previously unrecorded. AM fungal root colonization intensity and taxon richness varied along an environmental gradient, being higher in oligotrophic and lower in mesotrophic lakes. The overall phylogenetic structure of this aquatic fungal community differed from that described in terrestrial systems: The roots of L. dortmanna hosted more Archaeosporaceae and fewer Glomeraceae taxa than would be expected based on global data from terrestrial AM fungal communities.

Distinct germination response of endangered and common arable weeds to reduced water potential.

Arable weeds are one of the most endangered species groups in Europe. Modern agriculture and intensive land-use management are the main causes of their dramatic decline. However, besides the changes in land use, climate change may further challenge the adaptability of arable weeds. Therefore, we investigated the response pattern of arable weeds to different water potential and temperature regimes during the phase of germination. We expected that endangered arable weeds would be more sensitive to differences in water availability and temperature than common arable weeds. To this end, we set up a climate chamber experiment where we exposed seeds of five familial pairs of common and endangered arable weed species to different temperatures (5/15, 10/20 °C) and water potentials (0.0 to -1.2 MPa). The results revealed a significant relationship between the reaction of arable weed species to water availability and their Red List status. The effects of reduced water availability on total germination, mean germination time and synchrony were significantly stronger in endangered than in common arable weeds. Therefore, global climate change may present a further threat to the survival of endangered arable weed species.

Influence of early irradiation on in vitro red blood cell (RBC) storage variables of leucoreduced RBCs in additive solution SAG-M.

BACKGROUND: The only accepted way to avoid transfusion-associated graft-versus-host disease is irradiation of blood components. With respect to irradiation and associated storage time, different recommendations exist. We examined early irradiated (day +3) leucoreduced red blood cell units for irradiation-associated damages during storage. STUDY DESIGN AND METHODS: We studied 80 leucoreduced units from two manufacturers. All RBCs were stored in the additive solution saline-adenine-glucose-mannitol (SAG-M) and leucoreduced on collection day. Forty components were irradiated on day +3 with 30 Gy, 40 served as non-irradiated controls. Samples were drawn and analysed from these 80 units on days +3, +7, +14, +21, +28, +35 and +42. RESULTS: From day +14, there was a significant difference in the in vitro haemolysis rate between the non-irradiated and the irradiated components. Two of the irradiated units showed a haemolysis rate over the recommended limit of 0·8% on day +42. Potassium and lactate dehydrogenase activity increased faster in irradiated groups during storage. CONCLUSIONS: Our findings show that leucoreduced RBCs which are irradiated early after collection show an obvious radiation damage over storage period. Interestingly, on days +28, +35 and +42 the quality of RBCs which were irradiated on day +3 was nearly identical to the quality of RBCs which were irradiated on day +14 in a former series. Early irradiation does not cause more damage of RBCs during subsequent storage than irradiation on day +14. The maximum storage period of irradiated RBCs should remain restricted to 28 days from collection, however independently from the day of irradiation within this period.

T-cell subsets in autologous and allogeneic peripheral blood stem cell concentrates.

BACKGROUND AND OBJECTIVES: Regulatory T cells (Tregs) and other T-cell subsets are of importance in the setting of autologous and allogeneic stem cell transplantations. We conducted a study to assess the content of peripheral blood stem cell concentrates and related apheresis parameters in the autologous and allogeneic setting. MATERIAL AND METHODS: We characterized 53 donors, patients and peripheral blood stem cell concentrates (PBSC) regarding the content of CD45(+) cells, lymphocytes, CD3(+) cells, CD3(+) CD4(+) T cells, CD3(+) CD4(+) CD25(+) T cells, CD3(+) CD4(+) CD25(+) CD127(low/negative) Tregs and CD34(+) cells and calculated cell yields, recruitment factors and collection efficiency for all cell types. We compared allogeneic data with autologous data. RESULTS: Autologous PBSC show significantly lower concentrations of T-cell subsets compared to allogeneic PBSC (17,112/µl CD4(+), 14,858/µl CD4(+) CD25(+) and 1579/µl CD3(+) CD4(+) CD25(+) CD127(low/negative) Tregs in autologous compared to 65,539/µl CD4(+), 44,208(+) /µl CD4(+) CD25(+) and 5040/µl CD3(+) CD4(+) CD25(+) CD127(low/negative) Tregs in allogeneic PBSC, respectively), in contrast to CD34(+) concentrations (5342/µl CD34(+) in autologous compared to 2367/µl CD34(+) in allogeneic PBSC, respectively). Accordantly, all T-cell yields are lower in the autologous setting compared to allogeneic PBSC. However, recruitment factor and collection efficiency of all cell types are higher in autologous compared to allogeneic PBSC, but not all parameters differ significantly when groups are compared. CONCLUSION: T-cell subsets and especially Tregs are a substantial part of PBSC transplantation, as considerable recruitment during apheresis occurs. In large volume apheresis, the collection efficiency of Treg is comparable to that of CD34(+) cells, while recruitment factors are even higher.

Effects of reduced summer precipitation on productivity and forage quality of floodplain meadows at the Elbe and the Rhine River.

BACKGROUND: Floodplain meadows along rivers are semi-natural habitats and depend on regular land use. When used non-intensively, they offer suitable habitats for many plant species including rare ones. Floodplains are hydrologically dynamic ecosystems with both periods of flooding and of dry conditions. In German floodplains, dry periods may increase due to reduced summer precipitation as projected by climate change scenarios. Against this background, the question arises, how the forage quantity and quality of these meadows might change in future. METHODS: We report results of two field trials that investigated effects of experimentally reduced summer precipitation on hay quantity and quality of floodplain meadows at the Rhine River (2011-2012) and at two Elbe tributaries (2009-2011). We measured annual yield, the amount of hay biomass, and contents of crude protein, crude fibre, energy, fructan, nitrogen, phosphorus, and potassium. RESULTS: The annual yield decreased under precipitation reduction at the Rhine River. This was due to reduced productivity in the second cut hay at the Rhine River in which, interestingly, the contents of nitrogen and crude protein increased. The first cut at the Rhine River was unaffected by the treatments. At the Elbe tributaries, the annual yield and the hay quantity and quality of both cuts were only marginally affected by the treatments. CONCLUSION: We conclude that the yield of floodplain meadows may become less reliable in future since the annual yield decreased under precipitation reduction at the Rhine River. However, the first and agriculturally more important cut was almost unaffected by the precipitation reduction, which is probably due to sufficient soil moisture from winter/spring. As long as future water levels of the rivers will not decrease during spring, at least the use of the hay from the first cut of floodplain meadows appears reliable under climate change.

Correlation of the hypotonic shock response and extent of shape change with the new ThromboLUX ™.

ThromboLUX (TLX)-Score was compared with hypotonic shock response (HSR) and extent of shape change (ESC) in 99 samples from 42 platelet concentrates. Tests were performed in parallel and duplicate. Mean values for TLX Score, HSR and ESC were 30.3 ± 3.8%, 69.0 ± 12.2% and 23.2 ± 4.9%, respectively. We found no significant correlation between TLX Score and HSR or ESC (r = -0.158, P = 0.118 and r = -115, P = 0.255, respectively), whereas HSR and ESC correlated significantly (r = 0.351, P < 0.001). As TLX Score did not show significant correlation with HSR and ESC, the value of TLX for platelet quality testing remains unclear. Studies comparing these parameters with transfusion outcome are needed.

Negative and positive interactions among plants: effects of competitors and litter on seedling emergence and growth of forest and grassland species.

Living plant neighbours, but also their dead aboveground remains (i.e. litter), may individually exert negative or positive effects on plant recruitment. Although living plants and litter co-occur in most ecosystems, few studies have addressed their combined effects, and conclusions are ambivalent. Therefore, we examined the response in terms of seedling emergence and growth of herbaceous grassland and forest species to different litter types and amounts and the presence of competitors. We conducted a pot experiment testing the effects of litter type (grass, oak), litter amount (low, medium, high) and interspecific competition (presence or absence of four Festuca arundinacea individuals) on seedling emergence and biomass of four congeneric pairs of hemicryptophytes from two habitat types (woodland, grassland). Interactions between litter and competition were weak. Litter presence increased competitor biomass. It also had positive effects on seedling emergence at low litter amounts and negative effects at high litter amounts, while competition had no effect on seedling emergence. Seedling biomass was negatively affected by the presence of competitors, and this effect was stronger in combination with high amounts of litter. Litter affected seedling emergence while competition determined the biomass of the emerged individuals, both affecting early stages of seedling recruitment. High litter accumulation also reduced seedling biomass, but this effect seemed to be additive to competitor effects. This suggests that live and dead plant mass can affect species recruitment in natural systems, but the mechanisms by which they operate and their timing differ.

Buffy coat volume reduction for optimization of leucapheresis harvests produced by the autoMNC program.

BACKGROUND AND OBJECTIVES: Buffy coat (BC) volume reduction was evaluated in leucapheresis (LA) harvests due to the target monocyte yield and the red blood cell (RBC) content. A packed erythrocyte volume (PEV) of 7.5 ml should not be exceeded to avoid RBC debulking with loss of leucocytes (WBCs) and the monocyte fraction during monocyte counterflow elutriation, a next step of monocyte enrichment prior to cell culture. MATERIALS AND METHODS: Two hundred and fifty-three 5-l leucaphereses (autoMNC program) performed in 102 healthy blood donors (24 female and 78 male donors) were retrospectively analysed. Different categories of BC volumes were compared due to the quality of the LA products measured by blood counts and flow cytometry. RESULTS: Collection of maximum BC volume of 10 ml and more each collection cycle (product volume: 169 ± 21 ml) resulted in 1.58 ± 0·41 × 10e9 CD14(+) monocytes and high volume of packed erythrocyte (18.4 ± 8.8 ml). Low BC volume collection below 6 ml each collection cycle produced only 1.07 ± 0.40 × 10e9 CD14(+) monocytes but reduced PEV significantly by 64% (6.7 ± 4.1 ml). CONCLUSION: By reduction of the BC volume, the PEV in LA products could be reduced, which is a precondition for counterflow elutriation of monocytes. A BC volume between 7 and 8 ml per collection cycle should be adjusted to reduce PEV to 7.5 ml without relevant monocyte loss.

Standardised reporting protocol for endoscopic resection for Barrett oesophagus associated neoplasia: expert consensus recommendations.

Endoscopic resection (ER) is considered the therapy of choice for intraepithelial neoplasia associated with visible lesions and T1a adenocarcinoma. Pathologists are bound to encounter specimens collected via these techniques more frequently in their practice. A standardised protocol for handling, grossing, and assessing ER specimens should be adopted to ensure that all prognostic information and characteristics influencing treatment are included in reports (see Supplementary Video Abstract, http://links.lww.com/PAT/A22). The entire specimen should be appropriately oriented, processed and assessed. An ER specimen will commonly show intraepithelial neoplasia or invasive carcinoma. There are essential features that should be recorded if invasive carcinoma is found as they dictate further management and follow-up. These features are the margin status, depth of invasion, degree of differentiation and presence or absence of lymphovascular invasion. Important features such as duplication of muscularis mucosae should be recognised to avoid misinterpretation of depth of invasion. Key diagnostic and prognostic elements that are essential for optimal clinical decisions have been included in the reporting format proposed by the Structured Pathology Reporting committee of the Royal College of Pathologists of Australasia (RCPA).

The influence of four different anticoagulants on dynamic light scattering of platelets.

For testing of dynamic light scattering of platelets with ThromboLUX (TLX) in platelet-rich plasma (PRP) derived from venous whole blood (vWB), anticoagulation is needed. We compared TLX score in PRPs containing citrate, ethylene-diamine-tetraacetic-acid (EDTA), citrate-phosphate-dextrose-adenine (CPDA) or citrate-theophylline-adenosine-dipyridamole. Initial and late TLX scores were measured after 30-120 min or four to six hours, respectively. Compared with citrate, mean differences in initial TLX score were only significant for CPDA. Also, mean differences between initial and late TLX scores were only significant for CPDA. TLX failed to detect EDTA-induced platelet alterations. The clinical relevance of TLX needs further studies.

Comparison of a new microscopic system for the measurement of residual leucocytes in apheresis platelets with flow cytometry and manual counting.

BACKGROUND AND OBJECTIVES: Since 2001, all blood components in Germany must be leucocyte depleted. Recently, a new method for quality control of depletion was introduced. Our study aimed at the validation of the method for routine use in apheresis platelet concentrates. MATERIALS AND METHODS: We compared the new ADAM-rWBC device with manual counting in the Nageotte chamber and flow cytometry, two standard methods, by measuring residual leucocytes in 40 units of apheresis platelet concentrates and in six geometrical dilution series. RESULTS: Cell counts of residual leucocytes in the 40 units were below 10(6) cells per component with all methods, although mean cell counts were approximately 5 and 6 times higher in flow cytometry and ADAM-rWBC, respectively, compared to the Nageotte chamber. No unit with <10(6) leucocytes was regarded as contaminated. The dilution series showed acceptable accuracy, especially in the range around the cut-off (approximately 4·5 cells/µl in components with a volume of 220 ml) for regarding a concentrate as contaminated with leucocytes. No sample spiked with more than 4·5 cells/µl was counted as having less. CONCLUSION: In comparison with manual counting and flow cytometry, the ADAM-rWBC device performed equally. The method is suitable for routine screening of leucocyte contamination of apheresis platelets.

The novel allele, HLA-B*08:113, identified in a German cord blood donor and his mother.

The novel allele HLA-B*08:113 identified in two related individuals of Caucasian origin is described.

Plant movements and climate warming: intraspecific variation in growth responses to nonlocal soils.

Most range shift predictions focus on the dispersal phase of the colonization process. Because moving populations experience increasingly dissimilar nonclimatic environmental conditions as they track climate warming, it is also critical to test how individuals originating from contrasting thermal environments can establish in nonlocal sites. We assess the intraspecific variation in growth responses to nonlocal soils by planting a widespread grass of deciduous forests (Milium effusum) into an experimental common garden using combinations of seeds and soil sampled in 22 sites across its distributional range, and reflecting movement scenarios of up to 1600 km. Furthermore, to determine temperature and forest-structural effects, the plants and soils were experimentally warmed and shaded. We found significantly positive effects of the difference between the temperature of the sites of seed and soil collection on growth and seedling emergence rates. Migrant plants might thus encounter increasingly favourable soil conditions while tracking the isotherms towards currently 'colder' soils. These effects persisted under experimental warming. Rising temperatures and light availability generally enhanced plant performance. Our results suggest that abiotic and biotic soil characteristics can shape climate change-driven plant movements by affecting growth of nonlocal migrants, a mechanism which should be integrated into predictions of future range shifts.

First comparative evaluation of a new leukapheresis technology in non-cytokine-stimulated donors.

BACKGROUND AND OBJECTIVES: Leukapheresis is an important source for mononuclear cells (MNCs) used in adoptive immunotherapies. Differences in the apheresis technology concerning physical conditions during cell separation and the optical detection system can affect the product's cellular content. MATERIALS AND METHODS: In a paired analysis, twenty healthy non-cytokine-stimulated donors underwent MNC collection at the Spectra Optia (Terumo BCT, Lakewood, CO, USA) and the COM.TEC (Fresenius Kabi, Bad Homburg, Germany) device. In twelve donors, apheresis was additionally performed with the Amicus (Fenwal Inc., Lake Zurich, IL, USA). Donor response to leukapheresis and product composition was compared. RESULTS: Mean yields of CD14+ (CD3+) cells were 1·64±0·70x10(9) (2·36±0·96×10(9)) in the Spectra Optia, 1·45±0·50×10(9) (3·03±1·04×10(9)) in the COM.TEC and 1·20±0·37×10(9) (2·80±1·00×10(9)) in the Amicus products, respectively. The Spectra Optia collected significantly more CD14+ monocytes than the Amicus and significantly less CD3+ T cells than the COM.TEC (P=0·002 and P=0·021). Apheresis products of the Spectra Optia showed the significantly lowest red blood cell yields while the Amicus generated products with the significantly lowest platelet contents. CONCLUSIONS: Leukaphereses with the three devices resulted in almost equal total MNC yields. MNC products of the Spectra Optia and the Amicus could be used in preference for the monocyte enrichment by the Elutra system and the leukapheresis procedures could be also favourably applied in patients with low platelet counts. The COM.TEC is more efficient in monocyte and T-cell collection with the disadvantage of high residual non-target cell content in the products.

Residual aggregates in platelet products: what do we know?

BACKGROUND AND OBJECTIVES: Platelet (PLT) aggregates can occur during or after PLT component processing. However, very few reports investigating the phenomenon and its clinical significance have been published. In this review, currently available information about aggregates in PLT products is summarized and possible causal factors as well as preventive strategies are discussed. MATERIALS AND METHODS: A review of the MEDLINE® database for relevant publications from 1960 to May 2013 was conducted. RESULTS: It is well known that PLT aggregates may occur during or after the PLT product preparation process. These aggregates normally dissipate with rest and agitation. However, in some rare cases, the aggregates do not dissipate within 24 h and can persist up to the end of storage. Exposure to low temperature, low pH, short resting period after collection, different collection systems, presence of bubbles or foam inside the PLT bag, PLT-container interactions, proper product mixing and donor-dependent variables may have an impact on the formation of PLT aggregates. Although publications are rare, the presence of small numbers of PLT aggregates appears to have only limited impact on PLT in vitro quality. Furthermore, data on the clinical impact of PLT aggregates are lacking. CONCLUSION: Despite the fact that PLT aggregates occur in PLT products, published data on this topic remain scant. Considering the concern of clinicians about this phenomenon, more studies are needed which should focus on the possible clinical impact of such aggregates and precautions to avoid PLT aggregate formation in PLT products.