An international review of the characteristics of viral nucleic acid-amplification testing (NAT) reveals a trend towards the use of smaller pool sizes and individual donation NAT.

BACKGROUND AND OBJECTIVES: Nucleic acid-amplification testing (NAT) is used for screening blood donations/donors for blood-borne viruses. We reviewed global viral NAT characteristics and NAT-yield confirmatory testing used by blood operators. MATERIALS AND METHODS: NAT characteristics and NAT-yield confirmatory testing used during 2019 was surveyed internationally by the International Society of Blood Transfusion Working Party Transfusion-Transmitted Infectious Diseases. Reported characteristics are presented herein. RESULTS: NAT was mainly performed under government mandate. Human immunodeficiency virus (HIV), hepatitis C virus (HCV) and hepatitis B virus (HBV) NAT was performed on all donors and donation types, while selective testing was reported for West Nile virus, hepatitis E virus (HEV), and Zika virus. Individual donation NAT was used for HIV, HCV and HBV by ~50% of responders, while HEV was screened in mini-pools by 83% of responders performing HEV NAT. Confirmatory testing for NAT-yield samples was generally performed by NAT on a sample from the same donation or by NAT and serology on samples from the same donation and a follow-up sample. CONCLUSION: In the last decade, there has been a trend towards use of smaller pool sizes or individual donation NAT. We captured characteristics of NAT internationally in 2019 and provide insights into confirmatory testing approaches used for NAT-yields, potentially benefitting blood operators seeking to implement NAT.

International review of blood donation nucleic acid amplification testing.

BACKGROUND AND OBJECTIVES: Nucleic acid amplification testing (NAT), in blood services context, is used for the detection of viral and parasite nucleic acids to reduce transfusion-transmitted infections. This project reviewed NAT for screening blood donations globally. MATERIALS AND METHODS: A survey on NAT usage, developed by the International Society of Blood Transfusion Working Party on Transfusion-transmitted Infectious Diseases (ISBT WP-TTID), was distributed through ISBT WP-TTID members. Data were analysed using descriptive statistics. RESULTS: Forty-three responses were received from 32 countries. Increased adoption of blood donation viral screening by NAT was observed over the past decade. NAT-positive donations were detected for all viruses tested in 2019 (proportion of donations positive by NAT were 0.0099% for human immunodeficiency virus [HIV], 0.0063% for hepatitis C virus [HCV], 0.0247% for hepatitis B virus [HBV], 0.0323% for hepatitis E virus [HEV], 0.0014% for West Nile virus [WNV] and 0.00005% for Zika virus [ZIKV]). Globally, over 3100 NAT-positive donations were identified as NAT yield or solely by NAT in 2019 and over 22,000 since the introduction of NAT, with HBV accounting for over half. NAT-positivity rate was higher in first-time donors for all viruses tested except WNV. During 2019, a small number of participants performed NAT for parasites (Trypanosoma cruzi, Babesia spp., Plasmodium spp.). CONCLUSION: This survey captures current use of blood donation NAT globally. There has been increased NAT usage over the last decade. It is clear that NAT contributes to improving blood transfusion safety globally; however, there is a need to overcome economic barriers for regions/countries not performing NAT.

RHD-negative red cells may be avoided for patients with ambiguous serologic typing for the RHD antigen.

BACKGROUND AND OBJECTIVES: Serologic typing with monoclonal anti-D is mandatory for RHD antigen determination before transfusion, but due to aberrant (weak or partial) variants of RHD, results may be ambiguous and molecular RHD-typing is required. Before that, RHD-negative (RHD -) red blood cells concentrates (RBCs) shall be transfused to avoid anti-D formation, which probably leads to wastage of RHD - RBCs. STUDY DESIGN AND METHODS: All patients with ambiguous results in serologic RHD-typing and molecular RHD-typing were assessed retrospectively. The proportions of patients at risk for anti-D formation and the proportion of RHD - RBCs transfused unnecessarily were evaluated for the following transfusion strategies: (1) RHD-positive (RHD + )RBCs for all patients, (2) RHD + RBCs for patients with at least 2+ reaction with anti-D, (3) RHD + RBCs for patients with C and/or E in their RHCE-phenotype, (4) RHD + RBCs for patients with C and/or E and at least 2+ reaction, and (5) RHD - RBCs for all patients. RESULTS: A total of 112 patients were included. Most had weak D type 1-3 and a minority had other, rare RHD variants. The risk of anti-D formation was 4.5%, 2.9%, 1.8%, 1.0%, and 0% for strategies 1-5, respectively. The proportion of RHD - RBCs transfused unnecessarily was 0%, 49.5%, 0.9%, 50.5%, and 95.5%. CONCLUSION: Transfusing patients with a C and/or E in their RHCE-phenotype with RHD + RBCs resulted in a very low risk of immunization while avoiding wastage of RHD - RBCs. Therefore, this strategy should be used for some patients with ambiguous results in serologic RHD-typing and pending results of molecular RHD-typing.

Serum reactivity in dermatitis herpetiformis: an international multicentre study.

BACKGROUND: Dermatitis herpetiformis (DH) is a rare gluten-induced skin disorder characterized predominantly by IgA autoantibodies against endomysium, tissue transglutaminase (TG2/tTG), epidermal transglutaminase (TG3/eTG) and deamidated gliadin. To date, circulating autoantibody reactivity has not been systematically described. OBJECTIVES: Characterization of serum reactivities in DH. METHODS: This multicentre international study analysed sera from 242 patients with DH taken at the time of initial diagnosis. DH-specific IgA and IgG serum autoantibodies were analysed by indirect immunofluorescence (IF) on monkey oesophagus, and by enzyme-linked immunosorbent assay (ELISA) based on recombinant TG2/tTG, TG3/eTG and deamidated gliadin (GAF3X). RESULTS: IgA indirect IF microscopy on monkey oesophagus revealed the highest reactivity (84.3%; specificity 100%) followed by IgA TG2/tTG ELISA (78.5%, specificity 99.0%), IgA TG3/eTG ELISA (72.7%, specificity 95.0%) and IgA GAF3X ELISA (69.0%, specificity 98.5%). CONCLUSIONS: Serum IgA and IgG autoantibodies against endomysium, TG2/tTG, TG3/eTG and deamidated gliadin are highly prevalent in DH. Indirect IF microscopy on monkey oesophagus (IgA) provides the highest diagnostic accuracy that can be further enhanced by 4.5% when combined with IgA TG2/tTG ELISA.

Monitoring the SARS-CoV-2 Pandemic: Prevalence of Antibodies in a Large, Repetitive Cross-Sectional Study of Blood Donors in Germany-Results from the SeBluCo Study 2020-2022.

SARS-CoV-2 serosurveillance is important to adapt infection control measures and estimate the degree of underreporting. Blood donor samples can be used as a proxy for the healthy adult population. In a repeated cross-sectional study from April 2020 to April 2021, September 2021, and April/May 2022, 13 blood establishments collected 134,510 anonymised specimens from blood donors in 28 study regions across Germany. These were tested for antibodies against the SARS-CoV-2 spike protein and nucleocapsid, including neutralising capacity. Seroprevalence was adjusted for test performance and sampling and weighted for demographic differences between the sample and the general population. Seroprevalence estimates were compared to notified COVID-19 cases. The overall adjusted SARS-CoV-2 seroprevalence remained below 2% until December 2020 and increased to 18.1% in April 2021, 89.4% in September 2021, and to 100% in April/May 2022. Neutralising capacity was found in 74% of all positive specimens until April 2021 and in 98% in April/May 2022. Our serosurveillance allowed for repeated estimations of underreporting from the early stage of the pandemic onwards. Underreporting ranged between factors 5.1 and 1.1 in the first two waves of the pandemic and remained well below 2 afterwards, indicating an adequate test strategy and notification system in Germany.

Differences in Immunogenicity of Three Different Homo- and Heterologous Vaccination Regimens against SARS-CoV-2.

Background: Due to findings on adverse reactions and clinical efficacy of different vaccinations against SARS-CoV-2, the administration of vaccination regimens containing both adenoviral vector vaccines and mRNA-based vaccines has become common. Data are still needed on the direct comparison of immunogenicity for these different regimens. Methods: We compared markers for immunogenicity (anti-S1 IgG/IgA, neutralizing antibodies, and T-cell response) with three different vaccination regimens (homologous ChAdOx1 nCoV-19 (n = 103), or mixture of ChAdOx1 nCoV-19 with mRNA-1273 (n = 116) or BNT162b2 (n = 105)) at two time points: the day of the second vaccination as a baseline and 14 days later. Results: All examined vaccination regimens elicited measurable immune responses that were significantly enhanced after the second dose. Homologous ChAdOx1 nCoV-19 was markedly inferior in immunogenicity to all other examined regimens after administration of the second dose. Between the heterologous regimens, mRNA-1273 as second dose induced greater antibody responses than BNT162b2, with no difference found for neutralizing antibodies and T-cell response. Discussion: While these findings allow no prediction about clinical protection, from an immunological point of view, vaccination against SARS-CoV-2 with an mRNA-based vaccine at one or both time points appears preferable to homologous vaccination with ChAdOx1 nCoV-19. Whether or not the demonstrated differences between the heterologous regimens are of clinical significance will be subject to further research.

Kinetics of the Antibody Response to Boostering With Three Different Vaccines Against SARS-CoV-2.

BACKGROUND: Heterologous vaccinations against SARS-CoV-2 with ChAdOx1 nCoV-19 and a second dose of an mRNA-based vaccine have been shown to be more immunogenic than homologous ChAdOx1 nCoV-19. In the current study, we examined the kinetics of the antibody response to the second dose of three different vaccination regimens (homologous ChAdOx1 nCoV-19 vs. ChAdOx1 nCoV-19 + BNT162b2 or mRNA-1273) against SARS-CoV-2 in a longitudinal manner; whether there are differences in latency or amplitude of the early response and which markers are most suitable to detect these responses. METHODS: We performed assays for anti-S1 IgG and IgA, anti-NCP IgG and a surrogate neutralization assay on serum samples collected from 57 participants on the day of the second vaccination as well as the following seven days. RESULTS: All examined vaccination regimens induced detectable antibody responses within the examined time frame. Both heterologous regimens induced responses earlier and with a higher amplitude than homologous ChAdOx1 nCoV-19. Between the heterologous regimens, amplitudes were somewhat higher for ChAdOx1 nCoV-19 + mRNA-1273. There was no difference in latency between the IgG and IgA responses. Increases in the surrogate neutralization assay were the first changes to be detectable for all regimens and the only significant change seen for homologous ChAdOx1 nCoV-19. DISCUSSION: Both examined heterologous vaccination regimens are superior in immunogenicity, including the latency of the response, to homologous ChAdOx1 nCoV-19. While the IgA response has a shorter latency than the IgG response after the first dose, no such difference was found after the second dose, implying that both responses are driven by separate plasma cell populations. Early and steep increases in surrogate neutralization levels suggest that this might be a more sensitive marker for antibody responses after vaccination against SARS-CoV-2 than absolute levels of anti-S1 IgG.

Validation of a predictive model for identifying an increased risk for recurrence in adolescents and young adults with a first provoked thromboembolism.

BACKGROUND: To develop and validate a predictive model to determinate patients at increased risk to suffer from recurrence following a first provoked deep vein thrombosis (VTE). METHODS: Predictive variables, i.e. male sex [1 point], inherited thrombophilia (IT) status (none [0 points], single [1 point], combined variants [2 points]), blood group non-0, and age at first VTE onset were included into a risk assessment model, which was derived in 511 patients and then validated in 509 independent subjects. RESULTS: VTE recurrence risk score (maximum 4 points, range 0-3) was below two for patients scored as low-risk (LRS) and ≥2 for patients at high-risk (HRS). Within a median time of 3 years after withdrawal of anticoagulation (AC) recurrence rate in LRG (derivation) was 11.8% versus 26.0% in HRS (p < 0.001). In the validation cohort within 2.2 years the recurrence rate was 9.8% in LRS versus 30.1% in HRS (p < 0.001). In multivariable analysis adjusted for age at first VTE and blood group the recurrent risk in HRS was significantly increased compared with the LRS (derivation: hazard/95% confidence interval: 3.7/1.75-7.91; validation: 4.7/2.24-9.81; combined 5.2/1.92-13.9). Model specificity (sensitivity) was 79.0% (52.0%) in the derivation cohort compared with 78.0% (43.0%) in the validation group. In conclusion, in the prediction model presented here the risk of VTE recurrence was associated with male gender and combined ITs. Based on the negative predictive value calculated the model may identify patients with a first provoked VTE not being at risk for recurrence.

Completing the Donor History Questionnaire before the Donation Visit Can Improve Blood Safety.

Background and Objectives: In Germany, the donor history questionnaire (DHQ) is traditionally filled in at the donation center to avoid any influence of others. Since March 2020, it has been suggested to donors to answer the DHQ already at home and to call if they have any concerns to reduce the number of ineligible donors on-site during the COVID-19 pandemic. Materials and Methods: We evaluated the rate of ineligible donors before and after March 2020. Additionally, an anonymous online survey asking for the donors' attitude towards the DHQ was performed. It included questions on whether and for what reason the DHQ had been answered incorrectly in the past. Results: The rate of ineligible donors decreased by 27% (from 7.1% to 5.2%). In total, 5,556 of 10,252 invited donors completed the survey (54.2%). 88.6% reported either going through the DHQ at home or knowing all questions from their previous donations. 444 donors (8.0%) had at least once postponed a donation after reading the DHQ at home. 68 donors (1.2%) admitted having intentionally provided false answers in the past (9 at home, 43 on-site, 14 both, 2 unknown). Not wanting to be rejected once arriving at the donation center was an important motivation for 42% of donors answering incorrectly on-site. Details on 46 incorrect answers were provided: only 17 had no influence on donor eligibility or product quality. In 5 cases, some blood products might have had impaired quality. Truthful answers to 17 questions would have led to deferral, mostly due to increased risk for unrecognized viral infections transmitted by sexual contacts. For a further 7 questions, there was insufficient information available to determine possible consequences. Asked about their general opinion, 753 (13.6%) of all donors estimated the risk of incorrect answers being greater on-site, while 239 (4.3%) presumed an increased risk at home. Conclusion: Answering the DHQ prior to a donation visit prevented ineligible donors from visiting the donation center. Furthermore, it might improve honesty, as the discomfort of being deferred after arriving at the donation center was an important reason to answer incorrectly. Overall, there was no increased risk of donor or product safety, and potentially even a benefit.

Donors for SARS-CoV-2 Convalescent Plasma for a Controlled Clinical Trial: Donor Characteristics, Content and Time Course of SARS-CoV-2 Neutralizing Antibodies.

BACKGROUND: Convalescent plasma is one of the treatment options for COVID-19 which is currently being investigated in many clinical trials. Understanding of donor and product characteristics is important for optimization of convalescent plasma. METHODS: Patients who had recovered from CO-VID-19 were recruited as donors for COVID-19 convalescent plasma (CCP) for a randomized clinical trial of CCP for treatment of severe COVID-19 (CAPSID Trial). Titers of neutralizing antibodies were measured by a plaque-reduction neutralization test (PRNT). Correlation of antibody titers with host factors and evolution of neutralizing antibody titers over time in repeat donors were analysed. RESULTS: A series of 144 donors (41% females, 59% males; median age 40 years) underwent 319 plasmapheresis procedures providing a median collection volume of 850 mL and a mean number of 2.7 therapeutic units per plasmapheresis. The majority of donors had a mild or moderate course of COVID-19. The titers of neutralizing antibodies varied greatly between CCP donors (from <1:20 to >1:640). Donor factors (gender, age, ABO type, body weight) did not correlate significantly with the titer of neutralizing antibodies. We observed a significant positive correlation of neutralization titers with the number of reported COVID-19 symptoms and with the time from SARS-CoV-2 diagnosis to plasmapheresis. Neutralizing antibody levels were stable or increased over time in 58% of repeat CCP donors. Mean titers of neutralizing antibodies of first donation and last donation of repeat CCP donors did not differ significantly (1:86 at first compared to 1:87 at the last donation). There was a significant correlation of neutralizing antibodies measured by PRNT and anti-SARS-CoV-2 IgG and IgA antibodies which were measured by ELISA. CCP donations with an anti-SARS-CoV-2 IgG antibody content above the 25th percentile were substantially enriched for CCP donations with higher neutralizing antibody levels. CONCLUSION: We demonstrate the feasibility of collection of a large number of CCP products under a harmonized protocol for a randomized clinical trial. Titers of neutralizing antibodies were stable or increased over time in a subgroup of repeat donors. A history of higher number of COVID-19 symptoms and higher levels of anti-SARS-CoV-2 IgG and IgA antibodies in immunoassays can preselect donations with higher neutralizing capacity.

Role of prothrombin 19911 A>G polymorphism, blood group and male gender in patients with venous thromboembolism: Results of a German cohort study.

The role of the A>G polymorphism at position 19911 in the prothrombin gene (factor [F] 2 at rs3136516) as a risk factor for venous thromboembolism [VTE] is still unclear. To evaluate the presence of the F2 polymorphism in VTE patients compared to healthy blood donors and to adjust the results for common inherited thrombophilias [IT], age at onset and blood group [BG], and to calculate the risk of VTE recurrence. We investigated 1012 Caucasian patients with a diagnosis of VTE for the presence of the F2 rs3136516 polymorphism and compared these with 902 healthy blood donors. Odds ratios [OR] together with their 95% confidence intervals were calculated adjusted for F5 at rs6025, F2 at rs1799963, blood group, age and gender. In addition, we evaluated the risk of recurrent VTE during patient follow-up calculating hazard ratios [HR] together with their 95% CI. Compared with the AA wildtype, the F2 GG and AG genotypes (rs3136516) were associated with VTE (OR 1.48 and 1.45). The OR in F5 carriers compared to controls was 5.68 and 2.38 in patients with F2 (rs1799963). BG "non-O" was significantly more often diagnosed in patients compared to BG "O" (OR 2.74). VTE recurrence more often occurred in males (HR 2.3) and in carriers with combined thrombophilia (HR 2.11). Noteworthy, the rs3136516 polymorphism alone was not associated significantly with recurrence. In Caucasian patients with VTE the F2 GG/GA genotypes (rs3136516) were moderate risk factors for VTE. Recurrence was associated with male gender and combined thrombophilia.

Two Novel Variants in the Protein S Gene PROS1 Are Associated with Protein S Deficiency and Thrombophilia.

Protein S (PS) is an important anticoagulant. Its main function is to act as a non-enzymatical cofactor of activated protein C. PS deficiency is defined as low plasma levels of PS and/or loss of function associated with variable risk of venous thromboembolism (VTE). We report 2 novel variants in the PS gene (PROS1) which are associated with PS deficiency and severe thrombophilic diathesis in 2 patients. Patient 1 suffered from 3 VTE events, including a spontaneous VTE at the age of 19. Patient 2 suffered from 2 provoked VTE events. In both patients decreased plasma levels of PS antigen as well as decreased PS activity were found. Gene sequencing results showed a heterozygous deletion of 8 base pairs (c.938_945delTAAAATTT, p.Leu313Serfs13*) in exon 9 of the PROS1 gene in patient 1 and a missense variant (c.1613C>T, p.Ser538Phe) in patient 2. Due to the clinically proven history of recurrent VTE events in both patients, genetic testing of first-degree relatives is discussed.

Acquired von Willebrand syndrome in ECMO patients: A 3-year cohort study.

BACKGROUND: Bleeding is a common but possibly underreported side effect of Extracorporeal Membrane Oxygenation (ECMO). Impairment of primary hemostasis by acquired von Willebrand syndrome (aVWS) and platelet dysfunction as well as activation and consumption of plasmatic coagulation factors contribute to hemorrhage. The aim of the present cohort study of consecutively enrolled patients admitted to our ECMO center was to collect demographic, medical and laboratory data possibly associated with i) development of clinically relevant bleeding and/or ii) death during a 12-months follow-up. RESULTS: Within a 3-year period 338 white patients aged 18-89 years (median: 60; male 64.5%) were enrolled. 78 of 338 patients (23%) presented with clinical relevant bleeding symptoms. The overall death rate was 74.6% within a median time of 9 days (1-229) post intervention. Logistic-regression analysis adjusted for age and gender revealed that i) the presence of blood group O versus non-O (Odds ratio (OR)/95%CI: 1.9/1.007-3.41), ECMO duration per day (1.1/1.06-1.14), veno-venous versus veno-arterial ECMO cannulation (2.33/1.2-4.5) and the overall need for blood product administered per unit (1.02/1.016-1.028) was independenly associated with bleeding in patients suffering from aVWS. ii) Older age (increase per year) at ECMO start (1.015/1.012-1.029) and an increasing amount of blood product units were significantly related with death (1.007/1.001-1.013). Patients with veno-venous versus veno-arterial cannulation survived longer (0.48/0.24-0.94). CONCLUSION: In the present cohort study we found a clinical relevant bleeding rate of 23% in subjects with aVWS associated with blood group O, a longer ECMO duration and veno-venous cannulation.

Prevalence of antibodies against Hepatitis D virus (HDV) in blood donors in Northern Germany.

OBJECTIVE: To assess the prevalence of HDV infections in German blood donors. METHOD: 167 donors with acute/chronic or resolved HBV infection and detectable antibodies against Hepatitis B core antigen (anti-HBc) were tested for antibodies against HDV (anti-HDV) by competitive ELISA. Samples with detectable anti-HDV or with HBsAg and/or HBV DNA were additionally investigated for HDV RNA. RESULTS: In nine (5.4 %) of the 167 donors, also HBsAg and HBV DNA were detectable. Anti-HDV was detectable in two of the 167 donors (1.2 %), additional four donors (2.4 %) had a borderline result. All of these donors tested negative for HBsAg and HBV DNA. Neither in samples with anti-HDV nor in HBsAg-/HBV DNA-positive samples, HDV RNA was detectable. CONCLUSIONS: At least 1.2 % of anti-HBc-positive blood donors have had an HDV infection. Although there is some evidence for a somewhat higher prevalence of HDV, the overall prevalence of HDV in Northern Germany is low.

Impacts of platelet-rich fibrin and platelet-rich plasma on primary osteoblast adhesion onto titanium implants in a bisphosphonate in vitro model.

BACKGROUND: Osteoblast adhesion is a crucial step in osseointegration of dental implants and can be influenced by modification of implant surface or the addition of bioactive agents. Bisphosphonates affect bone turnover, attenuating bone healing in implants patients. PRP and PRF are sources of growth factors involved in osteoblast adhesion, improving subsequent bone healing. The aim of the study was to investigate the impacts of PRP and PRF on adhesion of bisphosphonate-pretreated osteoblasts on titanium implant surfaces using the cell-count wash assay, the MTT-assay as well as real-time-cell analyser assay and scanning electronic microscopy. METHODS: Titanium implants were colonised for 24 hours with osteoblasts and zolendronic acid, PRP or PRF in different combinations. Afterwards, primary osteoblast adhesion was evaluated by counting the number of attached cells using a wash-assay cell analysis. Scanning electronic microscopy was performed and evaluated semi-quantitatively to assess the influence of the different groups on the ultrastructural cell morphology, such as cell size and shape as well as length and number of filopodia. RESULTS: Zoledronic acid led to a decrease of osteoblast adherence onto implant surface. This effect was reversed by adding PRP or PRF. Scanning electronic microscopy showed that both PRP and PRF increased number and length of filopodia in adherent osteoblasts. CONCLUSIONS: Zoledronic acid decreased osteoblast adhesion on implant surfaces, and PRF as well as PRP increased primary adhesion of zoledronic acid-treated osteoblasts on implant surfaces in vitro. Therefore, PRP and PRF may improve initial bone apposition and primary healing of dental implants in patients with bisphosphonate treatment.

Positive impact of Platelet-rich plasma and Platelet-rich fibrin on viability, migration and proliferation of osteoblasts and fibroblasts treated with zoledronic acid.

Bisphosphonates are frequently used for the antiresorptive treatment in bone metastasis diseases or for osteoporosis. A side effect of this therapy is osteonecrosis of the jaw. This inhibits osteoclast function, but osteoblasts and fibroblasts are also negatively affected in terms of impaired proliferation. Additive local treatment with platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) promotes adhesion, proliferation and migration of cells due to high concentrations of growth factors like PDGF, TGF and IGF. The aim of the study was to investigate the effect of PRP or PRF on proliferation, migration and viability of osteoblasts and oral fibroblasts, treated with zoledronic acid (ZA). ZA treated fibroblasts and osteoblasts were exposed to PRP/PRF. Cell proliferation, migration and viability were measured using the real-time cell-analyzer assay (RTCA), the scratch assay and the MTT assay. There was a significant increase in closure of the scratch area by PRP/PRF treated osteoblasts (PRP = 40.6%, PRF = 100.0%, NC = 0.0%) as well as fibroblasts (PRP = 100.0%, PRF = 100.0%, NC = 12.7%) in comparison to the group of negative control (all p ≤ 0.05). Furthermore, the negative effect of ZA on cell migration was generally reduced in both cell lines using PRP/PRF. The viability and proliferation of cells decreased after exposure to ZA, whereas we observed an enhancement of cell viability within 24 hours by application of PRP/PRF in ZA treated cells. The negative effect of ZA on cell proliferation was especially reduced when using PRF. The use of PRF/PRP improves the behavior of ZA-treated cells, but PRF appears to have an advantage in comparison to PRP. This study demonstrates that treatment with PRF/PRP may have positive effects in the therapy of Bisphosphonate-Related Osteonecrosis of the Jaw (BRONJ).

Impact of incubation method on the release of growth factors in non-Ca2+-activated PRP, Ca2+-activated PRP, PRF and A-PRF.

The aim of this study was to investigate the influence of different incubation methods on the growth factor content of lysates of platelet-rich fibrin (PRF), advanced-platelet-rich fibrin (A-PRF) and platelet-rich plasma (PRP) products. A comparison of related studies suggests that the method of sample preparation has a significant influence on growth factor content. There are few reports on the comparison of non-Ca2+-activated PRP, Ca2+-activated PRP, A-PRF, and PRF, along with a lack of information on the release of PDGF-BB, TGF-ß1, and VEGF among the different incubation methods. The lysate preparation was made of non-Ca2+-activated PRP, Ca2+-activated PRP, PRF, and A-PRF, using a room-temperature, 37 °C, or freeze-thaw-freeze incubation method. Afterwards the VEGF, PDGF-BB, and TGF-ß1 content was investigated by running ELISA tests. Growth factor levels were significantly increased in the non-Ca2+-activated PRP with freeze-thaw-freeze incubation, and in the PRF preparation there was a significant disadvantage to using room temperature incubation for releasing growth factors. In conclusion, the freeze-thaw-freeze method is sufficient for releasing growth factors, and calcium activation is not necessary. Finally, the study demonstrates the possibility of preparing PRP products from platelet concentrates, so that preoperative blood sampling might not be required.

Parvovirus B19: What Is the Relevance in Transfusion Medicine?

Parvovirus B19 (B19V) has been discovered in 1975. The association with a disease was unclear in the first time after the discovery of B19V, but meanwhile, the usually droplet transmitted B19V is known as the infectious agent of the "fifth disease," a rather harmless children's illness. But B19V infects erythrocyte progenitor cells and thus, acute B19V infection in patients with a high erythrocyte turnover may lead to a life-threatening aplastic crisis, and acutely infected pregnant women can transmit B19V to their unborn child, resulting in a hydrops fetalis and fetal death. However, in many adults, B19V infection goes unnoticed and thus many blood donors donate blood despite the infection. The B19V infection does not impair the blood cell counts in healthy blood donors, but after the acute infection with extremely high DNA concentrations exceeding 1010 IU B19V DNA/ml plasma is resolved, B19V DNA persists in the plasma of blood donors at low levels for several years. That way, many consecutive donations that contain B19V DNA can be taken from a single donor, but the majority of blood products from donors with detectable B19V DNA seem not to be infectious for the recipients from several reasons: first, many recipients had undergone a B19V infection in the past and have formed protective antibodies. Second, B19V DNA concentration in the blood product is often too low to infect the recipient. Third, after the acute infection, the presence of B19V DNA in the donor is accompanied by presumably neutralizing antibodies which are protective also for the recipient of his blood products. Thus, transfusion-transmitted (TT-) B19V infections are very rarely reported. Moreover, in most blood donors, B19V DNA concentration is below 1,000 IU/ml plasma, and no TT-B19V infections have been found by such low-viremic donations. Cutoff for an assay for B19V DNA blood donor screening should, therefore, be approximately 1,000 IU/ml plasma, if a general screening of blood donors for single donation blood components is considered at all: for the overwhelming majority of transfusion recipients, B19V infection is not relevant as well as for the blood donors. B19V DNA screening of vulnerable patients after transfusion seems to be a more reasonable approach than general blood donor screening.