CD21 deficiency in 2 siblings and frequency of the associated mutation in the Danish population.

The clinical presentation of CD21 deficiency in 2 siblings caused by a novel mutation in the CD21 gene is reported, and the frequency of this mutation in the Danish population is explored. Successful treatment with IgG replacement in both patients with CD21 deficiency is also reported.

A Danish national, multicentre evaluation of the new donor vigilance system among different staff groups.

BACKGROUND AND OBJECTIVES: Two years after implementing a new national donor vigilance system, the Danish Haemovigilance Committee conducted a nationwide survey to evaluate the implementation among different staff groups. We present the results here. MATERIALS AND METHODS: The study was designed as an anonymous online survey to evaluate the satisfaction with the new registration, understanding of the parameters used and the user-friendliness. The REDCap platform was used. The questionnaire consisted of 22 questions. Ordinal variables were answered using five-point Likert scale (1 = strongly disagree to 5 = strongly agree). The data were analysed using descriptive statistics. Successful implementation was defined as mean overall satisfaction ≥4 and mean understanding of the individual components (adverse reaction category, severity and imputability) in the registration ≥4. RESULTS: In all, 104 staff members (77.9% donation staff) participated. The mean (SD) overall satisfaction among all participants was 3.96 (0.94), highest among medical doctors (4.43 (0.78)) and lowest for administrative or other personnel (2.78 (1.09)). The mean scores for understanding the adverse reaction categories, severity and imputability were 3.92 (0.94), 3.92 (0.94) and 3.88 (1.00), respectively. Experience with a previous donor vigilance system was associated with lower scores. The most successful implementation programme included a medical doctor for introduction and a contact person. CONCLUSION: The goal for successful implementation was not met. However, the overall attitude towards the new registration was positive and indicates that the system is suitable for different staff groups. Our results suggest that implementation could benefit from special attention to administrative staff and those accustomed to another donor vigilance system.

The new donor vigilance system in Denmark reveals regional differences in adverse reactions supposedly caused by variation in the registration.

BACKGROUND AND OBJECTIVES: In recent years, there has been an increased focus among blood bank professionals on the health and safety of blood donors. In 2019, the Danish Haemovigilance Committee designed a national donor vigilance system to improve the registration of adverse reactions (AR) in blood donors. The new donor vigilance system was implemented on 1 January 2020 and we here present the results from the first year of registration. MATERIALS AND METHODS: AR categories, severity level and imputability score were defined based on the definitions from the International Society of Blood Transfusion, AABB and the European Commission directive 2005/61/EC, respectively. RESULTS: Across all severity levels, AR in Danish blood donors were found to be rare (1498 per 100,000 donations). Only 0.2% of the registered reactions were classified as serious (2.7 per 100,000 donations). Large regional differences were seen in the registration of citrate reactions and haematomas. CONCLUSION: Significant differences across regions in what to categorize as an AR were persistent even when including a severity score in the reporting. The Danish Haemovigilance Committee will commence a national work to align the definitions but suggests that this matter is raised to an international level as part of the current work to agree upon definitions for assessment of donor AR.

Freeze-dried allograft-mediated gene or protein delivery of growth and differentiation factor 5 reduces reconstructed murine flexor tendon adhesions.

Advances in allograft processing have opened new horizons for clinical adaptation of flexor tendon allografts as delivery scaffolds for antifibrotic therapeutics. Recombinant adeno-associated-virus (rAAV) gene delivery of the growth and differentiation factor 5 (GDF-5) has been previously associated with antifibrotic effects in a mouse model of flexor tendoplasty. In this study, we compared the effects of loading freeze-dried allografts with different doses of GDF-5 protein or rAAV-Gdf5 on flexor tendon healing and adhesions. We first optimized the protein and viral loading parameters using reverse transcription polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and in vivo bioluminescent imaging. We then reconstructed flexor digitorum longus (FDL) tendons of the mouse hindlimb with allografts loaded with low and high doses of recombinant GDF-5 protein and rAAV-Gdf5 and evaluated joint flexion and biomechanical properties of the reconstructed tendon. In vitro optimization studies determined that both the loading time and concentration of the growth factor and viral vector had dose-dependent effects on their retention on the freeze-dried allograft. In vivo data suggest that protein and gene delivery of GDF-5 had equivalent effects on improving joint flexion function, in the range of doses used. Within the doses tested, the lower doses of GDF-5 had more potent effects on suppressing adhesions without adversely affecting the strength of the repair. These findings indicate equivalent antifibrotic effects of Gdf5 gene and protein delivery, but suggest that localized delivery of this potent factor should also carefully consider the dosage used to eliminate untoward effects, regardless of the delivery mode.

A mouse model of flexor tendon repair.

Mouse models offer invaluable cellular and molecular tools for the study of human pathologies including those associated with fibrotic and musculoskeletal diseases. In this methods manuscript, we describe a mouse model of repair and segmental reconstruction of flexor tendons, which in our laboratory has been an invaluable model to study tendon scarring and adhesions. Specifically, we describe in details all the surgical procedures involved, as well as the associated endpoint biomechanical assessments including a novel test of the flexion of the metatarsophalangeal joint as a measure of adhesions, and a standard protocol for biomechanical assessment of the tensile strength of the tendon and repair tissue.

Remodeling of murine intrasynovial tendon adhesions following injury: MMP and neotendon gene expression.

Tendon injury frequently results in the formation of adhesions that reduce joint range of motion. To study the cellular, molecular, and biomechanical events involved in intrasynovial tendon healing and adhesion formation, we developed a murine flexor tendon healing model in which the flexor digitorum longus (FDL) tendon of C57BL/6 mice was transected and repaired using suture. This model was used to test the hypothesis that murine flexor tendons heal with differential expression of matrix metalloproteases (MMPs), resulting in the formation of scar tissue as well as the subsequent remodeling of scar and adhesions. Healing tendons were evaluated by histology, gene expression via real-time RT-PCR, and in situ hybridization, as well as biomechanical testing to assess the metatarsophalangeal (MTP) joint flexion range of motion (ROM) and the tensile failure properties. Tendons healed with a highly disorganized fibroblastic tissue response that was progressively remodeled through day 35 resulting in a more organized pattern of collagen fibers. Initial repair involved elevated levels of Mmp-9 at day 7, which is associated with catabolism of damaged collagen fibers. High levels of Col3 are consistent with scar tissue, and gradually transition to the expression of Col1. Scleraxis expression peaked at day 7, but the expression was limited to the original tendon adjacent to the injury site, and no expression was present in granulation tissue involved in the repair response. The MTP joint ROM with standardized force on the tendon was decreased on days 14 and 21 compared to day 0, indicating the presence of adhesions. Peak expressions of Mmp-2 and Mmp-14 were observed at day 21, associated with tendon remodeling. At day 28, two genes associated with neotendon formation, Smad8 and Gdf-5, were elevated and an improvement in MTP ROM occurred. Tensile strength of the tendon progressively increased, but by 63 days the repaired tendons had not reached the tensile strength of normal tendon. The murine model of primary tendon repair, described here, provides a novel mechanism to study the tendon healing process, and further enhances the understanding of this process at the molecular, cellular, and biomechanical level.

Freeze-dried tendon allografts as tissue-engineering scaffolds for Gdf5 gene delivery.

Tendon reconstruction using grafts often results in adhesions that limit joint flexion. These adhesions are precipitated by inflammation, fibrosis, and the paucity of tendon differentiation signals during healing. In order to study this problem, we developed a mouse model in which the flexor digitorum longus (FDL) tendon is reconstructed using a live autograft or a freeze-dried allograft, and identified growth and differentiation factor 5 (Gdf5) as a therapeutic target. In this study we have investigated the potential of rAAV-Gdf5 -loaded freeze-dried tendon allografts as "therapeutically endowed" tissue-engineering scaffolds to reduce adhesions. In reporter gene studies we have demonstrated that recombinant adeno-associated virus (rAAV)-loaded tendon allografts mediate efficient transduction of adjacent soft tissues, with expression peaking at 7 days. We have also demonstrated that the rAAV-Gdf5 vector significantly accelerates wound healing in an in vitro fibroblast scratch model and, when loaded onto freeze-dried FDL tendon allografts, improves the metatarsophalangeal (MTP) joint flexion to a significantly greater extent than the rAAV-lacZ controls do. Collectively, our data demonstrate the feasibility and efficacy of therapeutic tendon allograft processing as a novel paradigm in tissue engineering in order to address difficult clinical problems such as tendon adhesions.

Adhesions in a murine flexor tendon graft model: autograft versus allograft reconstruction.

Reconstruction of flexor tendons often results in adhesions that compromise joint flexion. Little is known about the factors involved in the formation of flexor tendon graft adhesions. In this study, we developed and characterized a novel mouse model of flexor digitorum longus (FDL) tendon reconstruction with live autografts or reconstituted freeze-dried allografts. Grafted tendons were evaluated at multiple time points up to 84 days post-reconstruction. To assess the flexion range of the metatarsophalangeal joint, we developed a quantitative outcome measure proportional to the resistance to tendon gliding due to adhesions, which we termed the Gliding Coefficient. At 14 days post-grafting, the Gliding Coefficient was 29- and 26-fold greater than normal FDL tendon for both autografts and allografts, respectively (p < 0.001), and subsequently doubled for 28-day autografts. Interestingly, there were no significant differences in maximum tensile force or stiffness between live autograft and freeze-dried allograft repairs over time. Histologically, autograft healing was characterized by extensive remodeling and exuberant scarring around both the ends and the body of the graft, whereas allograft scarring was abundant only near the graft-host junctions. Gene expression of GDF-5 and VEGF were significantly increased in 28-day autografts compared to allografts and to normal tendons. These results suggest that the biomechanical advantages for tendon reconstruction using live autografts over devitalized allografts are minimal. This mouse model can be useful in elucidating the molecular mechanisms in tendon repair and can aid in preliminary screening of molecular treatments of flexor tendon adhesions.