Steroid resistance in Diamond Blackfan anemia associates with p57Kip2 dysregulation in erythroid progenitors

Despite the effective clinical use of steroids for the treatment of Diamond Blackfan anemia (DBA), the mechanisms through which glucocorticoids regulate human erythropoiesis remain poorly understood. We report that the sensitivity of erythroid differentiation to dexamethasone is dependent on the developmental origin of human CD34+ progenitor cells, specifically increasing the expansion of CD34+ progenitors from peripheral blood (PB) but not cord blood (CB). Dexamethasone treatment of erythroid-differentiated PB, but not CB, CD34+ progenitors resulted in the expansion of a newly defined CD34+CD36+CD71hiCD105med immature colony-forming unit-erythroid (CFU-E) population. Furthermore, proteomics analyses revealed the induction of distinct proteins in dexamethasone-treated PB and CB erythroid progenitors. Dexamethasone treatment of PB progenitors resulted in the specific upregulation of p57Kip2, a Cip/Kip cyclin-dependent kinase inhibitor, and we identified this induction as critical; shRNA-mediated downregulation of p57Kip2, but not the related p27Kip1, significantly attenuated the impact of dexamethasone on erythroid differentiation and inhibited the expansion of the immature CFU-E subset. Notably, in the context of DBA, we found that steroid resistance was associated with dysregulated p57Kip2 expression. Altogether, these data identify a unique glucocorticoid-responsive human erythroid progenitor and provide new insights into glucocorticoid-based therapeutic strategies for the treatment of patients with DBA.

Neutralizing Antibodies against SARS-CoV-2 and Other Human Coronaviruses

Coronavirus (CoV) disease 2019 (COVID-19) caused by severe acute respiratory syndrome (SARS)-CoV-2 (also known as 2019-nCoV) is threatening global public health, social stability, and economic development. To meet this challenge, this article discusses advances in the research and development of neutralizing antibodies (nAbs) for the prevention and treatment of infection by SARS-CoV-2 and other human CoVs.

Developmental differences between neonatal and adult human erythropoiesis

Studies of human erythropoiesis have relied, for the most part, on the in vitro differentiation of hematopoietic stem and progenitor cells (HSPC) from different sources. Here, we report that despite the common core erythroid program that exists between cord blood (CB)- and peripheral blood (PB)-HSPC induced toward erythroid differentiation in vitro, significant functional differences exist. We undertook a comparative analysis of human erythropoiesis using these two different sources of HSPC. Upon in vitro erythroid differentiation, CB-derived cells proliferated 4-fold more than PB-derived cells. However, CB-derived cells exhibited a delayed kinetics of differentiation, resulting in an increased number of progenitors, notably colony-forming unit (CFU-E). The phenotypes of early erythroid differentiation stages also differed between the two sources with a significantly higher percentage of IL3R^- GPA^- CD34⁺ CD36⁺ cells generated from PB- than CB-HSPCs. This subset was found to generate both burst-forming unit (BFU-E) and CFU-E colonies in colony-forming assays. To further understand the differences between CB- and PB-HSPC, cells at eight stages of erythroid differentiation were sorted from each of the two sources and their transcriptional profiles were compared. We document differences at the CD34, BFU-E, poly- and orthochromatic stages. Genes exhibiting the most significant differences in expression between HSPC sources clustered into cell cycle- and autophagy-related pathways. Altogether, our studies provide a qualitative and quantitative comparative analysis of human erythropoiesis, highlighting the impact of the developmental origin of HSPCs on erythroid differentiation.

Histocompatibility and immunogenetics in cord blood transplantation

This review of the immunogenetics of cord blood transplantation attempts to highlight the connections between classical studies and conclusions of the tissue transplantation field as a scholarly endeavor, exemplified by the work of Professor Hoecker, with the motivations and some recent and key results of clinical cord blood transplantation. The authors review the evolution of understanding of transplantation biology and find that the results of the application of cord blood stem cells to Transplantation Medicine are consistent with the careful experiments of the pioneers in the field, from the results of tumor and normal tissue transplants, histocompatibility immunogenetics, to cell and molecular biology. Recent results of the National Cord Blood Program of the New York Blood Center describe the functioning in cord blood transplantation of factors, well known in transplantation immunogenetics, like the Fl anti-parent effect and the tolerance-like status of donors produced by non-inherited maternal HLA antigens. Consideration of these factors in donor selection strategies can improve the prognosis of transplantation by characterizing "permissibility" in HLA-incompatible transplantation thereby increasing the probability of survival and reducing the likelihood of leukemic relapse.

A randomized, controlled Phase III trial of therapeutic plasma exchange with fresh-frozen plasma (FFP) prepared with amotosalen and ultraviolet A light compared to untreated FFP in thrombotic thrombocytopenic purpura

BACKGROUND

Photochemical treatment of fresh-frozen plasma (FFP) with amotosalen and ultraviolet (UV) A light (PCT FFP) results in inactivation of a broad spectrum of pathogens while retaining coagulation factor activity, antithrombotic proteins, and von Willebrand factor-cleaving protease (VWF-CP) activity.

STUDY DESIGN AND METHODS

A randomized, controlled, double-blind Phase III trial was conducted with PCT FFP or control FFP for therapeutic plasma exchange (TPE) in patients with thrombotic thrombocytopenic purpura (TTP). Owing to the rarity of this diagnosis, the trial was not powered to demonstrate small differences between treatment groups. Patients were treated with study FFP for a maximum of 35 days until remission was achieved (for a maximum of 30 daily study TPEs with no remission) plus an additional 5 days after remission.

RESULTS

Among the 35 patients treated, the primary endpoint, remission within 30 days, was achieved by 14 of 17 (82%) PCT patients and 16 of 18 (89%) control patients (p = 0.658) The 90 percent confidence interval for treatment difference in remission rate for test - control was (-0.291 to 0.163). Time to remission, relapse rates, time to relapse, total volume and number of FFP units exchanged, and number of study TPEs were not significantly different between groups. Improvement in VWF-CP and inhibitors was similar for both groups. The overall safety profile of PCT FFP was similar to control FFP. No antibodies to amotosalen neoantigens were detected.

CONCLUSION

The comparable results between treatment groups observed from this small trial suggest that TPE with PCT FFP was safe and effective for treatment of TTP.

Use of sentinel sites for daily monitoring of the US blood supply

BACKGROUND

This report describes the first year of a government-sponsored program that uses daily reports from 29 sentinel sites to monitor the capacity of the US blood supply to meet demand.

STUDY DESIGN AND METHODS

From August 15, 2001, to August 14, 2002, 29 sentinel sites provided daily reports of the number of units of RBCs in inventory, transfused, exported, and outdated by ABO and Rh, and platelets by random or apheresis donor. Days supply of each component category was calculated as the number of units in inventory reported on a day divided by the sum of units transfused, exported, and outdated on that day. Sites also provided daily responses to questions about threatened or actual shortages.

RESULTS

The median of the days supply of RBCs at the 26 hospital transfusion services was 7.2 days. However, median days supply varied substantially by site and by day of the week. A+, O+, and O- units accounted for 30, 35, and 12 percent of total inventory and were maintained at a median supply of 7.4, 6.4, and 9.5 days, respectively. Reports of threatened RBC shortages peaked in early January 2002 and again in early July 2002. The July 2002 peak was about twice the January 2002 peak. Inventories at community-based centers were similar to those at hospital transfusion services. Hospitals maintained only a 1-day supply of platelets. Eight percent of random and 4 percent of apheresis platelets were outdated. There were 20 reports that surgery had to be postponed or canceled because platelets were unavailable.

CONCLUSIONS

Inventories of RBCs maintained at the participating sites were sufficient, with only one brief exception, to meet local demand during the first year of this monitoring program. The weekly rate of threatened shortage reports was more sensitive than days inventory as a predictor of actual shortages of RBCs. Unlike RBCs, platelet days supply, reports of threatened or actual platelet shortages, and platelet outdate rates did not vary seasonally.