Proceedings of the ISCT scientific signature series symposium, "Advances in cell and gene therapies for lung diseases and critical illnesses": International Society for Cell & Gene Therapy, Burlington VT, US, July 16, 2021.

The ISCT Scientific Signature Series Symposium "Advances in Cell and Gene Therapies for Lung Diseases and Critical Illnesses" was held as an independent symposium in conjunction with the biennial meeting, "Stem Cells, Cell Therapies, and Bioengineering in Lung Biology and Diseases," which took place July 12-15, 2021, at the University of Vermont. This is the third Respiratory System-based Signature Series event; the first 2, "Tracheal Bioengineering, the Next Steps" and "Cellular Therapies for Pulmonary Diseases and Critical Illnesses: State of the Art of European Science," took place in 2014 and 2015, respectively. Cell- and gene-based therapies for respiratory diseases and critical illnesses continue to be a source of great promise and opportunity. This reflects ongoing advancements in understanding of the mechanisms by which cell-based therapies, particularly those using mesenchymal stromal cells (MSCs), can mitigate different lung injuries and the increasing sophistication with which preclinical data is translated into clinical investigations. This also reflects continuing evolution in gene transfer vectors, including those designed for in situ gene editing in parallel with those targeting gene or cell replacement. Therefore, this symposium convened global thought leaders in a forum designed to catalyze communication and collaboration to bring the greatest possible innovation and value of cell- and gene-based therapies for patients with respiratory diseases and critical illnesses.

Design and Characterization of Protein E-PilA, a Candidate Fusion Antigen for Nontypeable Haemophilus influenzae Vaccine.

Nontypeable Haemophilus influenzae (NTHi) is a pathogen known for being a frequent cause of acute otitis media in children and respiratory tract infections in adults with chronic obstructive pulmonary disease. In the present study, a vaccine antigen based on the fusion of two known NTHi adhesive proteins, protein E (PE) and a pilin subunit (PilA), was developed. The quality of the combined antigen was investigated through functional, biophysical, and structural analyses. It was shown that the PE and PilA individual structures are not modified in the PE-PilA fusion and that PE-PilA assembles as a dimer in solution, reflecting PE dimerization. PE-PilA was found to bind vitronectin by enzyme-linked immunosorbent assay, as isolated PE does. Disulfide bridges were conserved and homogeneous, which was determined by peptide mapping and top-down analysis of PE, PilA, and PE-PilA molecules. Finally, the PE-PilA crystal showed a PE entity with a three-dimensional (3D) structure similar to that of the recently published isolated PE, while the structure of the PilA entity was similar to that of a 3D model elaborated from two other type 4 pilin subunits. Taken together, our observations suggest that the two tethered proteins behave independently within the chimeric molecule and display structures similar to those of the respective isolated antigens, which are important characteristics for eliciting optimal antibody-mediated immunity. PE and PilA can thus be further developed as a single fusion protein in a vaccine perspective, in the knowledge that tethering the two antigens does not perceptibly compromise the structural attributes offered by the individual antigens.

A semi-automated mass spectrometric immunoassay coupled to selected reaction monitoring (MSIA-SRM) reveals novel relationships between circulating PCSK9 and metabolic phenotypes in patient cohorts.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a key regulator of circulating low density lipoprotein cholesterol (LDL-C) levels. Besides its full-length mature form, multiple variants of PCSK9 have been reported such as forms that are truncated, mutated and/or with posttranslational modifications (PTMs). Previous studies have demonstrated that most of these variants affect PCSK9's function and thereby LDL-C levels. Commercial ELISA kits are available for quantification of PCSK9, but do not allow discrimination between the various forms and PTMs of the protein. To address this issue and given the complexity and wide dynamic range of the plasma proteome, we have developed a mass spectrometric immunoassay coupled to selected reaction monitoring (MSIA-SRM) for the multiplexed quantification of several forms of circulating PCSK9 in human plasma. Our MSIA-SRM assay quantifies peptides spanning the various protein domains and the S688 phosphorylation site. The assay was applied in two distinct cohorts of obese patients and healthy pregnant women stratified by their circulating LDL-C levels. Seven PCSK9 peptides were monitored in plasma samples: one in the prodomain prior to the autocleavage site at Q152, one in the catalytic domain prior to the furin cleavage site at R218, two in the catalytic domain following R218, one in the cysteine and histidine rich domain (CHRD) and the C-terminal peptide phosphorylated at S688 and unmodified. The latter was not detectable in sufficient amounts to be quantified in human plasma. All peptides were measured with high reproducibility and with LLOQ and LOD below the clinical range. The abundance of 5 of the 6 detectable PCSK9 peptides was higher in obese patients stratified with high circulating LDL-C levels as compared to those with low LDL-C (p < 0.05). The same 5 peptides showed good and statistically significant correlations with LDL-C levels (0.55 < r < 0.65; 0.0002 ⩽ p ⩽ 0.002), but not the S688 phosphorylated peptide. However, this phosphopeptide was significantly correlated with insulin resistance (r = 0.48; p = 0.04). In the pregnant women cohort, none of the peptides were associated to LDL-C levels. However, the 6 detectable PCSK9 peptides, but not PCSK9 measured by ELISA, were significantly correlated with serum triglyceride levels in this cohort. Our results also suggest that PCSK9 circulates with S688 phosphorylated at high stoichiometry. In summary, we have developed and applied a robust and sensitive MSIA-SRM assay for the absolute quantification of all PCSK9 domains and a PTM in human plasma. This assay revealed novel relationships between PCSK9 and metabolic phenotypes, as compared to classical ELISA assays.

Efficacy and Safety of Umbilical Cord-Derived Mesenchymal Stromal Cell Therapy in Preclinical Models of Sepsis: A Systematic Review and Meta-analysis.

BACKGROUND: In preclinical studies, mesenchymal stromal cells (MSCs), including umbilical cord-derived MSCs (UC-MSCs), demonstrate the ability to modulate numerous pathophysiological processes related to sepsis; however, a systematic synthesis of the literature is needed to assess the efficacy of UC-MSCs for treating sepsis. OBJECTIVE: To examine the effects of UC-MSCs on overall mortality (primary outcome) as well as on organ dysfunction, coagulopathy, endothelial permeability, pathogen clearance, and systemic inflammation (secondary outcomes) at prespecified time intervals in preclinical models of sepsis. METHODS: A systematic search was conducted on Embase, Ovid MEDLINE, and Web of Science up to June 20, 2023. Preclinical controlled studies using in vivo sepsis models with systemic UC-MSC administration were included. Meta-analyses were conducted and expressed as odds ratios (OR) and ratios of the weighted means with 95% CI for categorical and continuous data, respectively. Risk of bias was assessed with the SYRCLE tool. RESULTS: Twenty-six studies (34 experiments, n = 1258 animals) were included in this review. Overall mortality was significantly reduced with UC-MSC treatment as compared to controls (OR: 0.26, 95% CI: 0.18-0.36). At various prespecified time intervals, UC-MSCs reduced surrogate measures of organ dysfunction related to the kidney, liver, and lung; reduced coagulopathy and endothelial permeability; and enhanced pathogen clearance from multiple sites. UC-MSCs also modulated systemic inflammatory mediators. No studies were rated as low risk across all SYCLE domains. CONCLUSIONS: These results demonstrate the efficacy of UC-MSC treatment in preclinical sepsis models and highlight their potential as a therapeutic intervention for septic shock.

Comparison of freshly cultured versus cryopreserved mesenchymal stem cells in animal models of inflammation: A pre-clinical systematic review.

Background: Mesenchymal stem cells (MSCs) are multipotent cells that demonstrate therapeutic potential for the treatment of acute and chronic inflammatory-mediated conditions. Although controversial, some studies suggest that MSCs may lose their functionality with cryopreservation which could render them non-efficacious. Hence, we conducted a systematic review of comparative pre-clinical models of inflammation to determine if there are differences in in vivo measures of pre-clinical efficacy (primary outcomes) and in vitro potency (secondary outcomes) between freshly cultured and cryopreserved MSCs. Methods: A systematic search on OvidMEDLINE, EMBASE, BIOSIS, and Web of Science (until January 13, 2022) was conducted. The primary outcome included measures of in vivo pre-clinical efficacy; secondary outcomes included measures of in vitro MSC potency. Risk of bias was assessed by the SYRCLE 'Risk of Bias' assessment tool for pre-clinical studies. Results: Eighteen studies were included. A total of 257 in vivo pre-clinical efficacy experiments represented 101 distinct outcome measures. Of these outcomes, 2.3% (6/257) were significantly different at the 0.05 level or less; 2 favoured freshly cultured and 4 favoured cryopreserved MSCs. A total of 68 in vitro experiments represented 32 different potency measures; 13% (9/68) of the experiments were significantly different at the 0.05 level or less, with seven experiments favouring freshly cultured MSC and two favouring cryopreserved MSCs. Conclusions: The majority of preclinical primary in vivo efficacy and secondary in vitro potency outcomes were not significantly different (p<0.05) between freshly cultured and cryopreserved MSCs. Our systematic summary of the current evidence base may provide MSC basic and clinical research scientists additional rationale for considering a cryopreserved MSC product in their pre-clinical studies and clinical trials as well as help identify research gaps and guide future related research. Funding: Ontario Institute for Regenerative Medicine.

Comparison of freshly cultured versus freshly thawed (cryopreserved) mesenchymal stem cells in preclinical in vivo models of inflammation: a protocol for a preclinical systematic review and meta-analysis.

BACKGROUND: Mesenchymal stem cells (MSCs) are multipotent cells that demonstrate therapeutic potential for the treatment of acute and chronic inflammatory-mediated conditions. Especially for acute conditions, it is critical to have a readily available freshly thawed (cryopreserved) MSC product for rapid administration. Although controversial, some studies suggest that MSCs may lose their functionality with cryopreservation which in turn could render them non-efficacious. OBJECTIVE: In controlled preclinical in vivo models of inflammation, to determine if there are differences in surrogate measures of preclinical efficacy between freshly cultured and freshly thawed MSCs METHODS/DESIGN: A systematic search for pre-clinical in vivo inflammatory model studies will compare freshly cultured to freshly thawed MSCs from any source. The primary outcomes will include measures of in vivo preclinical efficacy; secondary outcomes will include measures of in vitro MSC potency. Electronic searches for MEDLINE and EMBASE will be constructed and reviewed by the Peer Review of Electronic Search Strategies (PRESS) process. If applicable, study outcomes will be meta-analyzed using a random effects model. Risk of bias will be assessed by the SYRCLE "Risk of Bias" assessment tool for preclinical in vivo studies. DISCUSSION: The results of this systematic review will provide translational scientists, clinical trialists, health regulators, and the clinical and public community with the current pre-clinical evidence base related to the efficacy and potency of freshly cultured versus freshly thawed MSCs, help identify evidence gaps, and guide future related research. SYSTEMATIC REVIEW REGISTRATION: Protocol is submitted to PROSPERO for registration (pending confirmation) and will be submitted to Collaborative Approach to Meta-Analysis and Review of Animal Data from Experimental Studies (CAMARADES) for public posting.

Cell therapy with intravascular administration of mesenchymal stromal cells continues to appear safe: An updated systematic review and meta-analysis.

BACKGROUND: Characterization of the mesenchymal stromal cell (MSC) safety profile is important as this novel therapy continues to be evaluated in clinical trials for various inflammatory conditions. Due to an increase in published randomized controlled trials (RCTs) from 2012-2019, we performed an updated systematic review to further characterize the MSC safety profile. METHODS: MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and Web of Science (to May 2018) were searched. RCTs that compared intravascular delivery of MSCs to controls in adult populations were included. Pre-specified adverse events were grouped according to: (1) immediate, (2) infection, (3) thrombotic/embolic, and (4) longer-term events (mortality, malignancy). Adverse events were pooled and meta-analyzed by fitting inverse-variance binary random effects models. Primary and secondary clinical efficacy endpoints were summarized descriptively. FINDINGS: 7473 citations were reviewed and 55 studies met inclusion criteria (n = 2696 patients). MSCs as compared to controls were associated with an increased risk of fever (Relative Risk (RR) = 2·48, 95% Confidence Interval (CI) = 1·27-4·86; I2 = 0%), but not non-fever acute infusional toxicity, infection, thrombotic/embolic events, death, or malignancy (RR = 1·16, 0·99, 1·14, 0·78, 0·93; 95% CI = 0·70-1·91, 0·81-1·21, 0·67-1·95, 0·65-0·94, 0·60-1·45; I2 = 0%, 0%, 0%, 0%, 0%). No included trials were ended prematurely due to safety concerns. INTERPRETATIONS: MSC therapy continues to exhibit a favourable safety profile. Future trials should continue to strengthen study rigor, reporting of MSC characterization, and adverse events. FUNDING: Stem Cell Network, Ontario Institute for Regenerative Medicine and Ontario Research Fund.

Posttranslational modification of proprotein convertase subtilisin/kexin type 9 is differentially regulated in response to distinct cardiometabolic treatments as revealed by targeted proteomics.

BACKGROUND: The proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secreted protein that interacts with the low-density lipoprotein (LDL) receptor at the surface of hepatocytes to regulate circulating LDL cholesterol levels. High circulating PCSK9 levels have been associated with elevated LDL cholesterol. Recently, the Food and Drug Administration of the United States approved new LDL cholesterol-lowering drugs that specifically target the inhibition of PCSK9. Similar to most human proteins, PCSK9 exists in multiple forms as it is the target of posttranslational modifications (PTMs) such as proteolytic cleavage, phosphorylation, and others, which can affect its biological activity. However, commercially available assays, such as enzyme-linked immunosorbent assays, do not discriminate between these forms. OBJECTIVE: To investigate, in 2 patient cohorts, the relationships between circulating levels of multiple forms of PCSK9 and cardiometabolic interventions or treatments known to reduce LDL cholesterol levels. METHODS: PCSK9 forms were measured in plasma: (1) in 20 patients before and 6 months after bariatric surgery and (2) in 132 patients before and 12 months after daily statin treatment. A series of specific peptides used as surrogates for various PCSK9 forms were quantified by a novel semiautomated proteomic assay termed protein affinity capture coupled to quantitative mass spectrometry. RESULTS: Bariatric surgery resulted in a decrease in the plasma level of PCSK9 prodomain (P < .05), but did not result in a significant change in other measured PCSK9 forms. Statin treatment resulted in an increase in all measured plasma PCSK9 peptides (P < .001), but a 25% decrease in the phosphorylated state of PCSK9 at S688 (P < .05). CONCLUSIONS: These unexpected findings indicate that measuring the circulating levels of the various domains and PTMs of PCSK9 provides more in depth information than total PCSK9 and that the prodomain and the phosphorylated state of S688 may represent novel biomarkers to explore in cardiometabolic diseases and response to treatment. In addition, our data generated new hypotheses on the function of PCSK9 PTMs in health and disease.

Effect of high dose folic acid supplementation in pregnancy on pre-eclampsia (FACT): double blind, phase III, randomised controlled, international, multicentre trial.

OBJECTIVE: To determine the efficacy of high dose folic acid supplementation for prevention of pre-eclampsia in women with at least one risk factor: pre-existing hypertension, prepregnancy diabetes (type 1 or 2), twin pregnancy, pre-eclampsia in a previous pregnancy, or body mass index ≥35. DESIGN: Randomised, phase III, double blinded international, multicentre clinical trial. SETTING: 70 obstetrical centres in five countries (Argentina, Australia, Canada, Jamaica, and UK). PARTICIPANTS: 2464 pregnant women with at least one high risk factor for pre-eclampsia were randomised between 2011 and 2015 (1144 to the folic acid group and 1157 to the placebo group); 2301 were included in the intention to treat analyses. INTERVENTION: Eligible women were randomised to receive either daily high dose folic acid (four 1.0 mg oral tablets) or placebo from eight weeks of gestation to the end of week 16 of gestation until delivery. Clinicians, participants, adjudicators, and study staff were masked to study treatment allocation. MAIN OUTCOME MEASURE: The primary outcome was pre-eclampsia, defined as hypertension presenting after 20 weeks' gestation with major proteinuria or HELLP syndrome (haemolysis, elevated liver enzymes, low platelets). RESULTS: Pre-eclampsia occurred in 169/1144 (14.8%) women in the folic acid group and 156/1157 (13.5%) in the placebo group (relative risk 1.10, 95% confidence interval 0.90 to 1.34; P=0.37). There was no evidence of differences between the groups for any other adverse maternal or neonatal outcomes. CONCLUSION: Supplementation with 4.0 mg/day folic acid beyond the first trimester does not prevent pre-eclampsia in women at high risk for this condition. TRIAL REGISTRATION: Current Controlled Trials ISRCTN23781770 and ClinicalTrials.gov NCT01355159.

Effect of folic acid supplementation in pregnancy on preeclampsia: the folic acid clinical trial study.

Preeclampsia (PE) is hypertension with proteinuria that develops during pregnancy and affects at least 5% of pregnancies. The Effect of Folic Acid Supplementation in Pregnancy on Preeclampsia: the Folic Acid Clinical Trial (FACT) aims to recruit 3,656 high risk women to evaluate a new prevention strategy for PE: supplementation of folic acid throughout pregnancy. Pregnant women with increased risk of developing PE presenting to a trial participating center between 8(0/7) and 16(6/7) weeks of gestation are randomized in a 1 : 1 ratio to folic acid 4.0 mg or placebo after written consent is obtained. Intent-to-treat population will be analyzed. The FACT study was funded by the Canadian Institutes of Health Research in 2009, and regulatory approval from Health Canada was obtained in 2010. A web-based randomization system and electronic data collection system provide the platform for participating centers to randomize their eligible participants and enter data in real time. To date we have twenty participating Canadian centers, of which eighteen are actively recruiting, and seven participating Australian centers, of which two are actively recruiting. Recruitment in Argentina, UK, Netherlands, Brazil, West Indies, and United States is expected to begin by the second or third quarter of 2013. This trial is registered with NCT01355159.

Effect of an organized lipid matrix on lipid absorption and clinical outcomes in patients with cystic fibrosis.

OBJECTIVES: To compare the absorption of a lysophosphatidylcholine, monoglyceride, and fatty acid matrix (organized lipid matrix, OLM) with that of a triacylglycerol (TG)-based fat meal in patients with cystic fibrosis (CF). STUDY DESIGN: Five adolescents with CF and 3 control patients were given fat meals supplemented with retinyl palmitate of either OLM or TG at a 2-week interval. In a clinical trial, 73 patients with CF were randomly assigned to nutritional supplements containing either OLM or TG for a 1-year double-blind trial followed by a 6-month observation period. RESULTS: The peak increases and areas under the curve for TG and retinyl palmitate after the fat meal were 10-fold higher after OLM than after the TG fat load and did not differ from values obtained in control patients. OLM led to better clinical outcomes in terms of energy intake from the diet, weight-for-age Z score, essential fatty acid status, vitamin E, and retinol binding protein. Height-for-age Z score and FEV(1) only reached statistical significance at the end of the 6-month observation period. CONCLUSIONS: These results suggest that OLM is a readily absorbable source of fat and energy in CF and is an effective nutritional supplement.