Previously we reported on the mid- to long-term follow-up in the first clinical trial to use a completely autologous tissue-engineered graft in the high pressure circulation. In these early studies, living grafts were built from autologous fibroblasts and endothelial cells obtained from small skin and vein biopsies. The graft was assembled using a technique called tissue-engineering by self-assembly (TESA), where robust conduits were grown without support from exogenous biomaterials or synthetic scaffolding. One limitation with this earlier work was the long lead times required to build the completely autologous vascular graft. Here we report the first implant of a frozen, devitalized, completely autologous Lifeline™ vascular graft. In a departure from previous studies, the entire fibroblast layer, which provides the mechanical backbone of the graft, was air-dried then stored at −80°C until shortly before implant. Five days prior to implant, the devitalized conduit was rehydrated, and its lumen was seeded with living autologous endothelial cells to provide an antithrombogenic lining. The graft was implanted as an arteriovenous shunt between the brachial artery and the axillary vein in a patient who was dependent upon a semipermanent dialysis catheter placed in the femoral vein. Eight weeks postoperatively, the graft functions without complication. This strategy of preemptive skin and vein biopsy and cold-preserving autologous tissue allows the immediate availability of an autologous arteriovenous fistula, and is an important step forward in our strategy to provide allogeneic tissue-engineered grafts available “off-the-shelf”.

Aims: Angiotensin-converting enzyme 2 (ACE2) is the cellular entry point for severe acute respiratory syndrome coronavirus (SARS-CoV-2)—the cause of coronavirus disease 2019 (COVID-19). However, the effect of renin-angiotensin system (RAS)-inhibition on ACE2 expression in human tissues of key relevance to blood pressure regulation and COVID-19 infection has not previously been reported. Methods and results: We examined how hypertension, its major metabolic co-phenotypes, and antihypertensive medications relate to ACE2 renal expression using information from up to 436 patients whose kidney transcriptomes were characterized by RNA-sequencing. We further validated some of the key observations in other human tissues and/or a controlled experimental model. Our data reveal increasing expression of ACE2 with age in both human lungs and the kidney. We show no association between renal expression of ACE2 and either hypertension or common types of RAS inhibiting drugs. We demonstrate that renal abundance of ACE2 is positively associated with a biochemical index of kidney function and show a strong enrichment for genes responsible for kidney health and disease in ACE2 co-expression analysis. Conclusion: Our results indicate that neither hypertension nor antihypertensive treatment is likely to alter the expression of the key entry receptor for SARS-CoV-2 in the human kidney. Our data further suggest that in the absence of SARS-CoV-2 infection, kidney ACE2 is most likely nephro-protective but the age-related increase in its expression within lungs and kidneys may be relevant to the risk of SARS-CoV-2 infection.

Background: Acute myocardial infarction (MI) leads to an irreversible loss of proper cardiac function. Application of stem cell therapy is an attractive option for MI treatment. Adipose tissue has proven to serve as a rich source of stem cells (ADSCs). Taking into account the different morphogenesis, anatomy, and physiology of adipose tissue, we hypothesized that ADSCs from different adipose tissue depots may exert a diverse multipotency and cardiogenic potential. Methods: The omental, pericardial, and epicardial adipose tissue samples were obtained from organ donors and patients undergoing heart transplantation at our institution. Human foreskin fibroblasts were used as the control group. Isolated ADSCs were analyzed for adipogenic and osteogenic differentiation capacity and proliferation potential. The immunophenotype and constitutive gene expression of alkaline phosphatase (ALP), GATA4, Nanog, and OCT4 were analyzed. DNA methylation inhibitor 5-azacytidine was exposed to the cells to stimulate the cardiogenesis. Finally, reprogramming towards cardiomyocytes was initiated with exogenous overexpression of seven transcription factors (ESRRG, GATA4, MEF2C, MESP1, MYOCD, TBX5, ZFPM2) previously applied successfully for fibroblast transdifferentiation toward cardiomyocytes. Expression of cardiac troponin T (cTNT) and alpha-actinin (Actn2) was analyzed 3 weeks after initiation of the cardiac differentiation. Results: The multipotent properties of isolated plastic adherent cells were confirmed with expression of CD29, CD44, CD90, and CD105, as well as successful differentiation toward adipocytes and osteocytes; with the highest osteogenic and adipogenic potential for the epicardial and omental ADSCs, respectively. Epicardial ADSCs demonstrated a lower doubling time as compared with the pericardium and omentum-derived cells. Furthermore, epicardial ADSCs revealed higher constitutive expression of ALP and GATA4. Increased Actn2 and cTNT expression was observed after the transduction of seven reprogramming factors, with the highest expression in the epicardial ADSCs, as compared with the other ADSC subtypes and fibroblasts. Conclusions: Human epicardial ADSCs revealed a higher cardiomyogenic potential as compared with the pericardial and omental ADSC subtypes as well as the fibroblast counterparts. Epicardial ADSCs may thus serve as the valuable subject for further studies on more effective methods of adult stem cell differentiation toward cardiomyocytes.