Prior COVID-19 infection may increase risk for developing endothelial dysfunction following hematopoietic cell transplantation.

Endothelial dysfunction underlies many of the major complications following hematopoietic cell transplantation (HCT), including transplant-associated thrombotic microangiopathy (TA-TMA), veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS), and engraftment syndrome (ES). Emerging evidence similarly implicates endothelitis and microangiopathy in severe COVID-19-related multi-system organ dysfunction. Given the overlap in these two illness states, we hypothesize that prior COVID-19 infection may increase risk for HCT-related endotheliopathies. This retrospective, multicenter study included patients aged 0-25 years who underwent autologous or allogeneic HCT for any indication between January 1, 2020 and September 21, 2021, with close attention to those infected with COVID-19 in either the six months prior to transplant or twelve months following transplant. Incidences of TA-TMA, VOD/SOS, and ES were compared among patients with COVID-19 infection pre-HCT and post-HCT, as well as with historical controls who were never infected with SARS-CoV-2. Those who underwent HCT following COVID-19 infection displayed significantly increased rates of TA-TMA compared to those who were never infected. Additionally, our data suggests a similar trend for increased VOD/SOS and ES rates, although this did not reach statistical significance. Therefore, a history of COVID-19 infection prior to undergoing HCT may be a nonmodifiable risk factor for endothelial-related complications following HCT. Further studies are warranted to better clarify this relationship among larger cohorts and in the era of the Omicron SARS-CoV-2 variants.

Quality Improvement in Hematopoietic Stem Cell Transplant and Cellular Therapy: Using the Model for Improvement to impact Outcomes.

Quality improvement and quality assurance form a complementary and independent relationship. Quality assurance measures compliance against industry standards using audits, whereas quality improvement is a continuous process focused on processes and systems that can improve care. The Model for Improvement is a robust quality improvement tool that transplant and cellular therapy teams can use to redesign healthcare processes. The Model for Improvement uses several components addressed in sequence to organize and critically evaluate improvement activities. Unlike other health sciences clinical research, quality improvement projects, and research are based on dynamic hypotheses that develop into observable, serial tests of change with continuous collection and feedback of performance data to stakeholders.

No evidence for significant transdifferentiation of bone marrow into pancreatic beta-cells in vivo.

Several recent studies have suggested that the adult bone marrow harbors cells that can differentiate into tissues from all three germ layers. Other reports have contradicted these findings or attributed them to cell fusion. In this study, we investigated whether bone marrow-derived cells contribute to the renewal of adult pancreatic endocrine cells, in particular insulin-producing beta-cells, in vivo. To address this issue, we studied mice transplanted with green fluorescent protein (GFP)-positive, sex-mismatched bone marrow. We also extended our studies to pancreatic injury models (partial pancreatectomy and streptozotocin administration). All animals showed stable full donor chimerism in the peripheral blood and microscopic analysis at 4-6 weeks and 3 months after transplantation, indicating that the GFP(+) and Y chromosome-positive donor bone marrow contributed substantially to blood, lymphatic, and interstitial cells in the pancreas. However, after examining >100,000 beta-cells, we found only 2 beta-cells positive for GFP, both of which were in control animals without pancreatic injury. Thus our study results did not support the concept that bone marrow contributes significantly to adult pancreatic beta-cell renewal.

Redifferentiation of insulin-secreting cells after in vitro expansion of adult human pancreatic islet tissue.

Cellular replacement therapy holds promise for the treatment of diabetes mellitus but donor tissue is severely limited. Therefore, we investigated whether insulin-secreting cells could be differentiated in vitro from a monolayer of cells expanded from human donor pancreatic islets. We describe a three-step culture protocol that allows for the efficient generation of insulin-producing cell clusters from in vitro expanded, hormone-negative cells. These clusters express insulin at levels of up to 34% that of average freshly isolated human islets and secrete C-peptide upon membrane depolarization. They also contain cells expressing the other major islet hormones (glucagon, somatostatin, and pancreatic polypeptide). The source of the newly differentiated endocrine cells could either be indigenous stem/progenitor cells or the proliferation-associated dedifferentiation and subsequent redifferentiation of mature endocrine cells. The in vitro generated cell clusters may be efficacious in providing islet-like tissue for transplantation into diabetic recipients.