Systematic review and meta-analysis of cell therapy for COVID-19: global clinical trial landscape, published safety/efficacy outcomes, cell product manufacturing and clinical delivery

During the pandemic of severe respiratory distress syndrome coronavirus 2 (SARS-CoV2), many novel therapeutic modalities to treat Coronavirus 2019 induced disease (COVID-19) were explored. This study summarizes 195 clinical trials of advanced cell therapies targeting COVID-19 that were registered over the two years between January 2020 to December 2021. In addition, this work also analyzed the cell manufacturing and clinical delivery experience of 26 trials that published their outcomes by July 2022. Our demographic analysis found the highest number of cell therapy trials for COVID-19 was in United States, China, and Iran (N=53, 43, and 19, respectively), with the highest number per capita in Israel, Spain, Iran, Australia, and Sweden (N=0.641, 0.232, 0,223, 0.194, and 0.192 trials per million inhabitants). The leading cell types were multipotent mesenchymal stromal/stem cells (MSCs), natural killer (NK) cells, and mononuclear cells (MNCs), accounting for 72%, 9%, and 6% of the studies, respectively. There were 24 published clinical trials that reported on infusions of MSCs. A pooled analysis of these MSC studies found that MSCs provide a relative risk reduction for all-cause COVID-19 mortality of RR=0.63 (95% CI 0.46 to 0.85). This result corroborates previously published smaller meta-analyses, which suggested that MSC therapy demonstrated a clinical benefit for COVID-19 patients. The sources of the MSCs used in these studies and their manufacturing and clinical delivery methods were remarkably heterogeneous, with some predominance of perinatal tissue-derived products. Our results highlight the important role that cell therapy products may play as an adjunct therapy in the management of COVID-19 and its related complications, as well as the importance of controlling key manufacturing parameters to ensure comparability between studies. Thus, we support ongoing calls for a global registry of clinical studies with MSC products that could better link cell product manufacturing and delivery methods to clinical outcomes. Although advanced cell therapies may provide an important adjunct treatment for patients affected by COVID-19 in the near future, preventing pathology through vaccination still remains the best protection to date. We conducted a systematic review and meta-analysis of advanced cell therapy clinical trials as potential novel treatment for COVID-19 (resulting from SARS-CoV-2 coronavirus infection), including analysis of the global clinical trial landscape, published safety/efficacy outcomes (RR/OR), and details on cell product manufacturing and clinical delivery. This study had a 2-year observation interval from start of January 2020 to end of December 2021, including a follow-up period until end of July to identify published outcomes, which covers the most vivid period of clinical trial activity, and is also the longest observation period studied until today. In total, we identified 195 registered advanced cell therapy studies for COVID-19, employing 204 individual cell products. Leading registered trial activity was attributed to the USA, China, and Iran. Through the end of July 2022, 26 clinical trials were published, with 24 out of 26 articles employing intravenous infusions (IV) of mesenchymal stromal/stem cell (MSC) products. Most of the published trials were attributed to China and Iran. The cumulative results from the 24 published studies employing infusions of MSCs indicated an improved survival (RR=0.63 with 95% Confidence Interval 0.46 to 0.85). Our study is the most comprehensive systematic review and meta-analysis on cell therapy trials for COVID-19 conducted to date, clearly identifying the USA, China, and Iran as leading advanced cell therapy trial countries for COVID-19, with further strong contributions from Israel, Spain, Australia and Sweden. Although advanced cell therapies may provide an important adjunct treatment for patients affected by COVID-19 in the future, preventing pathology through vaccination remains the best protection.

Control of neutrophil influx during peritonitis by transcriptional cross-regulation of chemokine CXCL1 by IL-17 and IFN-γ

Neutrophil infiltration is a hallmark of peritoneal inflammation, but mechanisms regulating neutrophil recruitment in patients with peritoneal dialysis (PD)-related peritonitis are not fully defined. We examined 104 samples of PD effluent collected during acute peritonitis for correspondence between a broad range of soluble parameters and neutrophil counts. We observed an association between peritoneal IL-17 and neutrophil levels. This relationship was evident in effluent samples with low but not high IFN-γ levels, suggesting a differential effect of IFN-γ concentration on neutrophil infiltration. Surprisingly, there was no association of neutrophil numbers with the level of CXCL1, a key IL-17-induced neutrophil chemoattractant. We investigated therefore the production of CXCL1 by human peritoneal mesothelial cells (HPMCs) under in vitro conditions mimicking clinical peritonitis. Stimulation of HPMCs with IL-17 increased CXCL1 production through induction of transcription factor SP1 and activation of the SP1-binding region of the CXCL1 promoter. These effects were amplified by TNFα. In contrast, IFN-γ dose-dependently suppressed IL-17-induced SP1 activation and CXCL1 production through a transcriptional mechanism involving STAT1. The SP1-mediated induction of CXCL1 was also observed in HPMCs exposed to PD effluent collected during peritonitis and containing IL-17 and TNFα, but not IFN-γ. Supplementation of the effluent with IFN-γ led to a dose-dependent activation of STAT1 and a resultant inhibition of SP1-induced CXCL1 expression. Transmesothelial migration of neutrophils in vitro increased upon stimulation of HPMCs with IL-17 and was reduced by IFN-γ. In addition, HPMCs were capable of binding CXCL1 at their apical cell surface. These observations indicate that changes in relative peritoneal concentrations of IL-17 and IFN-γ can differently engage SP1-STAT1, impacting on mesothelial cell transcription of CXCL1, whose release and binding to HPMC surface may determine optimal neutrophil recruitment and retention during peritonitis. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Increased gene expression of the cardiac endothelin system in obese mice

Obesity is a well-known risk factor of atherosclerosis and heart failure. In the human heart, a local endothelin system containing prepro-endothelin-1, endothelin-converting enzyme-1, and endothelin receptors A and B has been described. The endothelin system is activated in heart failure; however, the impact of obesity on the cardiac endothelin system is unknown. In this study, 18-week-old male C57BL/6 mice fed either a control diet or a high-fat diet for 10 weeks were analyzed. High-fat diet significantly increased the body weight of the animals and augmented low-density lipoprotein, high-density lipoprotein, and cholesterol plasma levels, compared to control. The animal groups showed no significant differences in left ventricular size or function (heart rate, ejection fraction, fractional shortening, left ventricular posterior wall thickness, cardiac output) after control or high-fat diet. We did not observe signs of cardiac hypertrophy or changes in markers of cardiac fibrosis in these heart samples. The cardiac expression of prepro-endothelin-1 mRNA, endothelin-converting enzyme-1 mRNA, and protein and endothelin receptors A and B mRNA was increased in 18-week-old obese C57BL/6 mice compared to animals with normal weight (p<0.05 vs. control). Furthermore, endothelin-1 plasma levels showed an increasing trend. In conclusion, an increased expression of genes of the endothelin system was observed in the hearts of 18-week-old mice after high-fat diet, possibly contributing to later cardiovascular complications of obesity.

Abstract 442: Cardiomyocyte Specific mTORC1 Deletion Precipitates Interstitial Fibrosis, Heart Failure And Loss Of Female Cardio Protection

Mechanistic target of rapamycin (mTOR) kinase operates in two functionally and structurally distinct multiprotein complexes mTORC1 and mTORC2. mTORC1 including its defining raptor protein is a critical mediator of myocardial growth. We induced cardiomyocyte specific raptor-KO (cKO) deletion to investigate a sex specific role of mTORC1 during cardiac adaptation in normotensive DOCA-salt mice. Untypical for this mild cardiac stress model, raptor-cKO females had sharper decrease in EF (51 vs. 26%) than males (50 vs. 32%) already at 3 weeks after start of DOCA-salt challenge. Male raptor-cKO mice mounted eccentric hypertrophic response upon DOCA-salt indicated by heart weight/tibia length ratios (6.7 to 8.0) as compared to their WT litters (6.6 to 7.6). In contrast female raptor-cKO (5.8 to 6.4) minimally differed from their litters (5.8 to 6.6). Severe dilative phenotype was detected in both sexes regardless of DOCA-salt challenge. In addition, we found tremendous diffuse left ventricular fibrosis which was also more prominent in raptor-cKO females. Collagen depositions in the LV visualized by Sirius red staining increased 10fold in males (1.0 to 10.6%) and 15fold in females (0.9 to 15.7%), respectively. Expression of raptor protein in the heart was diminished by 80% in raptor cKO mice of both sexes what lead to similar extent of decreased activity of direct mTORC1 downstream targets phospho-S6 ribosomal protein and phospho-4E-BP1Ser65 (68% reduction in males vs. 61% in females. Over-compensatory mTORC2 activation in cKO animals via phospho-AKTSer473 (12fold increase) and induction of anti-apoptotic signaling was similar in both sexes. However, raptor-cKO females failed to up-regulate expression of mitochondrial genes such as Mtnd1 (ND1), mt-Co1 (COX1) and Atp5i (ATP5k), stressing sex differences in mTORC1 dependent mitochondrial adaptation. In addition, transmission electron microscopy (TEM) points towards structural alterations of mitochondrial morphology.

Intact mTORC1 function is important for myocardial adaptation in both sexes. More severe phenotype in females further implicates mTORC1 to be essential for intrinsic female cardio protection.

Low-density lipoproteins induce the renin-angiotensin system and their receptors in human endothelial cells

Increased levels of low-density lipoproteins are well-established risk factors of endothelial dysfunction and the metabolic syndrome. In this study, we evaluated the effect of native low-density lipoprotein (nLDL) and oxidized LDL (oxLDL) on the expression of genes of the renin-angiotensin system (angiotensin-converting enzyme, ACE; angiotensin II type 1 receptor, AT(1)) and their receptors (low-density lipoprotein receptor: LDLR; lectin-like oxLDL receptor: LOX-1; toll-like receptor 4: TLR4) in primary cultures of human umbilical vein endothelial cells. ACE and AT(1) expressions were significantly increased after stimulation with nLDL and oxLDL. OxLDL receptor LOX-1 showed a maximum induction after 7 hours. Increased LOX-1 protein expression in response to oxLDL could be blocked by a LOX-1-specific antibody. TLR4 expression was increased by nLDL and oxLDL as well. We conclude that LDL and oxLDL can activate the renin-angiotensin system and their receptors LDLR, LOX-1, and TLR4 in human endothelial cells. These data suggest a novel link between hypercholesterolemia and hypertension in patients with the metabolic syndrome.

Upregulation of endothelin receptor B in human endothelial cells by low-density lipoproteins

Low-density lipoproteins (LDLs) represent the most important treatable risk factors for coronary artery disease. Although it has been previously shown that hypercholesterolemia stimulates the endothelin system, the effects of increased levels of LDL on endothelial endothelin receptors have not been previously studied. In particular, the influence of native and oxidatively modified LDLs (nLDLs and oxLDLs) and the regulatory mechanisms in endothelial cells are currently unknown. Human endothelial cells almost exclusively express the endothelin receptor type B (ET(B)). Therefore, the effect of nLDL and oxLDL on the expression of ET(B) was studied in primary cultures of human umbilical vein endothelial cells (HUVEC). HUVEC were stimulated by nLDL and oxLDL in a time-dependent (1-12 hrs) and dose-dependent (25-100 microg/ml) manner. To analyze signal transduction pathways involved in the regulation of ET(B), protein kinase C (PKC) was inhibited using 100 nM Ro-31-8220. The mRNA expression of ET(B) was determined by quantitative reverse transcription-polymerase chain reaction and ET(B) protein expression by Western blot. Native LDL induced ET(B) mRNA after 1 hr (100 microg/ml, 199 +/- 35%, n = 15, P < 0.05 vs. control). Stimulation of HUVEC with oxLDL increased ET(B) mRNA expression (1 hr, 100 microg/ml oxLDL: 308 +/- 48%, n = 15, P < 0.05 vs. control) as well. Induction of ET(B) was also found on the protein level. nLDL was even more potent than oxLDL in inducing ET(B) protein expression. Induction of ET(B) expression by oxLDL is mediated by PKC. These data demonstrate that low-density lipoproteins even independent of oxidative modification are potent inducers of ET(B) receptors at the mRNA and protein level in HUVEC. Given the nitric oxide-releasing capacity of endothelial ET(B) receptors, this effect may represent a possible vasoprotective mechanism.

Novel Nox inhibitor of oxLDL-induced reactive oxygen species formation in human endothelial cells

In this study, we investigated effects of a novel NAD(P)H oxidase (Nox)-inhibitor 3-benzyl-7-(2-benzoxazolyl)thio-1,2,3-triazolo[4,5-d]pyrimidine (VAS2870) on oxidized low-density lipoprotein (oxLDL)-mediated reactive oxygen species (ROS) formation in human endothelial cells. Primary cultures of human umbilical vein endothelial cells were cultured to confluence and ROS formation was induced with 50microg/ml oxLDL for 2h. ROS formation was detected by chemiluminescence (CL) using the Diogenes reagent. OxLDL induced ROS formation in human endothelial cells (171+/-12%; n=10, P<0.05 vs. control). This augmented ROS formation in response to oxLDL was completely inhibited by the Nox inhibitor VAS2870 (101+/-9%; n=7, P<0.05 vs. oxLDL). Similar results were obtained with superoxide dismutase (91+/-7%; n=7, P<0.05 vs. oxLDL). However, the Nox4 mRNA expression level was neither changed by oxLDL nor VAS2870. We conclude that VAS2870 could provide a novel strategy to inhibit the augmented endothelial superoxide anion formation in response to cardiovascular risk factors.

Native and oxidized low-density lipoproteins stimulate endothelin-converting enzyme-1 expression in human endothelial cells

This study addressed the question how different lipoproteins modulate the expression of endothelin-converting enzyme-1 (ECE-1) in human endothelial cells. The effect of native and oxidized low-density lipoproteins (nLDL, oxLDL) on expression of ECE-1, prepro-endothelin-1, and endothelin-1 peptide was studied in primary cultures of human endothelial cells. Native and oxidized LDL increased ECE-1 mRNA after 1 h, reaching its maximum at 100 microg/ml (1.9- and 2.5-fold, respectively). Furthermore, ECE-1 protein expression, prepro-endothelin-1 mRNA, and endothelin-1 peptide release were increased in response to nLDL or oxLDL. Induction of ECE-1 by nLDL and of prepro-endothelin-1 by oxLDL was reduced by protein kinase C inhibition. Increased expression of ECE-1 mRNA by oxLDL and of prepro-endothelin-1 by nLDL was blocked by an angiotensin II receptor type 1 antagonist. Our data provide evidence for a new mechanism how increased LDL plasma levels might contribute to enhanced endothelin-1 release in patients with hypercholesterolemia.