Validation and cost-effectiveness of an in-house dithiothreitol (DTT) treatment protocol for daratumumab patients in a large tertiary care hospital provides gateway for implementation in smaller community hospitals.

BACKGROUND: Treatment of multiple myeloma with daratumumab (DARA) is increasing fast. Unfortunately, this antibody also attaches to red blood cells (RBCs) and mimics an autoantibody's panreactivity during pre-transfusion testing, necessitating specialized techniques, (e.g. dithiothreitol (DTT)) for alloantibody detection. Many hospitals use a reference lab for such testing, increasing both cost and turn-around time (TAT). Herein, we compare the cost and TAT, pre and post-implementation of an in-house DTT protocol. METHODS: We designed a validation of our in-house DTT protocol from Nov to Dec 2017 with full implementation on January 1, 2018. We retrospectively reviewed all pre-transfusion tests on DARA patients from Feb 2016 to April 2018, pre and post-implementation of in-house DTT testing. Descriptive statistics were used for patient demographics and a Student t-test was used to compare cost and TATs (pre and post-implementation). RESULTS: We identified 49 patients on DARA treatment requiring transfusion. Samples from these patients were sent to the reference lab 104 times and were tested in-house 28 times. The average TAT for the reference lab was 19h25 m compared to our in-house TAT of 5h9m (an average time-savings of 14h16 m). We spent approximately $33,800 ($325 per test) for 104 reference lab samples versus $806.12 (˜$28.79 per test) for in-house testing of 28 samples. CONCLUSION: We provide an easily implementable DTT protocol for pre-transfusion testing community hospitals and beyond. As more monoclonal antibodies are developed and approved for clinical use, the lessons learned with DARA will expand to deal with interference from future targeted therapies.

Integrated mRNA and miRNA profiling revealed deregulation of cellular stress response in bone marrow mesenchymal stem cells derived from patients with immune thrombocytopenia.

Our understanding of the pathogenesis of immune thrombocytopenia (ITP) remains limited due to the complexity and heterogeneity of the disease. Recently, we observed that bone marrow mesenchymal stem cells (MSCs) derived from ITP patients exhibited growth defects and functional abnormalities that might be involved in the breakdown of self-tolerance. However, the underlying mechanism remains unclear. In this study, we profiled the expression of both mRNAs and miRNAs by utilizing the microarray technique and deciphered the mechanism underlying the impairment of MSCs derived from ITP patients (MSC-ITP). In total, we identified 740 genes and 32 miRNAs that were differentially expressed between ITP patients and controls. A compromised unfolded protein response (UPR) and decreased DNA transcription were shown to be significantly related to MSC-ITP. The interaction of miRNA with mRNA suggested that the cellular stress response, the UPR, and DNA transcription may be involved in the defects observed in MSC-ITP. Key differentially expressed genes were further validated by RT-PCR. Our results highlight that defects in the cellular stress response, as shown by a compromised UPR and differential DNA transcription, play key roles in causing the abnormalities observed in MSC-ITP. These data might contribute to a better understanding of the abnormal bone marrow niche and provide new insights into the pathogenesis of ITP.

ADAMTS13 and its variants promote angiogenesis via upregulation of VEGF and VEGFR2.

Severe plasma ADAMTS13 deficiency results in the clinical disorder thrombotic thrombocytopenic purpura. However, other potential pathophysiological roles of ADAMTS13 in endothelial cell biology remain unexplored. The goals of this study were to understand the angiogenic pathways ADAMTS13 activates and to identify the important structural components of ADAMTS13 that stimulate angiogenesis. Incubation of human umbilical vein endothelial cells (HUVEC) with 150 ng/mL (1 nM) of recombinant human ADAMTS13 induced VEGF expression by 53 % and increased VEGF mRNA by over sixfold, both within 10 min; the measured VEGF levels steadily decreased over 2 h, as shown by Western blot and ELISA. Phosphorylation of VEGFR2 was significantly enhanced in HUVEC after incubation with ADAMTS13 (1 nM). Structure-function analysis showed that an ADAMTS13 variant containing thrombospondin type 1 (TSP1) 2-8 repeats (TSP1 2-8), TSP1 2-8 plus CUB domains (TSP1 2-8 plus CUB), or TSP1 5-8 repeats plus CUB domains (TSP1 5-8 plus CUB) increased HUVEC proliferation by 41-54 % as compared to the EBM-2 controls. Chemotaxis assays further demonstrated that the TSP1 domains of ADAMTS13 increased HUVEC migration by 2.65-fold. Incubation of HUVEC with both ADAMTS13 variants containing TSP1 repeats and anti-VEGF IgG abrogated the enhanced effect of ADAMTS13 on proliferation, migration, and VEGFR2 phosphorylation. In conclusion, ADAMTS13-induced endothelial cell angiogenesis occurs via the upregulation of VEGF and phosphorylation of VEGFR2. This angiogenic activity depends on the C-terminal TSP1 repeats of ADAMTS13.