ECMO for the immunocompromised pediatric patient: Our experience

Objectives: To present a series of immunosuppressed patients (oncohematological disease, congenital immunosuppression, hematopoietic stem cell (HSCT), and solid organ transplant) assisted on ECMO. Method(s): Descriptive, retrospective study (2011-2020) of a cohort of 9 immunosuppressed patients, supported on ECMO. Medical records were reviewed and demographic, clinical, and analytical variables were collected. Result(s): In our series of 9 patients, 5 were male, the median age was 8 years [RIC 3-11 years]. Considering the underlying disease, 6 were oncologic, 1 liver transplant and 2 with congenital immunodeficiency after HSCT. 4 were under active chemotherapy (median 6 days after the last cycle [RIC 5-188]). 6 were admitted due to acute respiratory failure, 3 due to hemodynamic instability (3/9), (one septic shock). The median PEEP was 12 [RIC 9-15] and FiO2 100% (81-100%). 78% (6) required vasoactive drugs (median inotropic score 35 [RIC 0-75]. 40%. 5 had severe neutropenia and/or plateletopenia in the 24 hours prior to ECMO, and alterations in acid-base balance (median pH 7. 1 [RIC 6.9-7.15]. 5 were on multiorgan failure. TPrimary ECMO transport was performed in 4 patients (44%). Cannulation was peripheral in 80% (57% cervical, 43% femoral) and central in 20%;70% VA-ECMO. Median time of assistance was 15 days [RIC 3.5-31.5] in cardiac ECMO (4), and 29 days [RIC 13.5-42] and in pulmonary ECMO (n=5). The median total time of admission was 45 days [RIC 27-59]. 9 had an infection, 2 COVID after HSCT, and 8 bleeding complications, but only one required surgical revision. Renal replacement therapy was used in 5 (median 9 days [RIC 5-34.5]). Other therapies used were polymyxin hemadsorption(2), intratracheal surfactant(2), plasma exchange(1), infusion of mesenchymal cells(1) and specific memory T lymphocytes(2). 4 patients died, 5 survived decannulation, 2 died later, with an overall survival rate to hospital discharge of 33% (3/9). Conclusion(s): Despite having a worse prognosis, ECMO can increase survival in immunosuppressed patients, in situations that are challenging and require a multidisciplinary approach.

Characterization of Mesenchymal Cell from BAL of post COVID-19 patient whit fibrosis

Increasing number of severe COVID 19 patients develop pulmonary Fibrosis, but the management of this complication is still unclear due to a lack of clinical trials. Aim of this study was to characterize mesenchymal cells (MC) isolated from 10 broncho-alveolar lavage (BAL, at 2 months after discharge) from patients with COVID19 fibrosis (COVID19-f) and to compare them with those isolated from 8 patients with collagen tissue diseaseassociated interstitial fibrosis(CTD-ILD). BAL fluid (BALf) levels of TGFbeta, VEGF, TIMP2, RANTES, IL6, IL8, and PAI1 were assessed by ELISA. Primary MC foci were cultured and expanded in D-MEM +10% FBS, characterized by flow cytometry and osteogenic and adipogenic differentiation. Collagen 1 production (+/-TGF-beta) was tested by WB and mRNA expression. BALf cytokine and GF levels were comparable in the two groups. Efficiency of MC isolation from BAL was 100% in COVID-f compared to 65% in CTD-ILD. MC antigen surface expression of CD105, CD73, CD90 (>90%, respectively), CD45, CD34, CD19 and HLA-DR (<5%, respectively) was comparable. None of MC samples differentiated in adipocytes, while COVID19-f were positive for calcium deposition. COVID19-f MC showed at WB, higher Collagen 1 production with respect to CTD-ILD with TGF-beta stimulation. Our preliminary data suggest MC from COVID19-f share several features with CTD-ILD but might have a higher response to fibrogenic and differentiation signals.

Generation Of Macro-scale And Mature Lung Organoids Through Engineering Cell Microenvironment

Purpose/Objectives: <Most used lower respiratory tract models consist of cell monolayers which lack of tissue and organ level response and of in-vivo phenotype. Ex-vivo lung tissues have short viability and limited availability. Lung organoids, which recapitulates better the 3D cellular complex structures, architecture, and in-vivo function, fail to reach maturity even after 85 -185 days of culture. Therefore, these models have a limited use to study fetal lung diseases. Other lung models, consist of only one structure of the lower track, such as bronchial tubes or alveoli, but fail to recapitulate the whole organ structure. In this work, cell microenvironment was used to promote the self-organization of epithelial and mesenchymal cells into macro-structures, aiming to mimic the whole and adult lower respiratory tract model> Methodology: <Different parts of the microenvironment were considered to create a compliant matrix. Alginate-Gelatin hydrogels were used for 3D encapsulation of mesenchymal origin cells. This hydrogel provided a stiffness like the one on the lung. Base membrane zone proteins were used to induce the attachment and guidance of epithelial cells into 3D structures. The interactions between both cell types, further guided them into lung fate. The morphology of resulting organoids was analyzed using immunostaining and confocal microscopy, LSM710, with the purpose of evaluate polarization, protein markers, and different cell populations. Quantitative PCR was performed to evaluate and compare the expression of lung fate genes with traditional cell monocultures.> Results: <The engineered microenvironment and protocol development done in this work resulted in macro-scale structures, in which branching morphogenesis occurred at day 21. Different structures were identified in the organoid including bronchial tube, bronchioles, and alveoli. Polarization of the organoids was confirmed by visualization of E-cadherin, and ZO-1. Expression of Surfactant Protein B and C into the organoids confirmed the presence of alveolar type II cells, which are only present in the later development stage. Surfactant Protein B, Transmembrane protease, serine 2, TMPRSS-2, and Angiotensin-converting enzyme 2, ACE2 were found to be significantly higher expressed into the organoids in comparison with traditional epithelial cells monolayers.> Conclusion/Significance: <Growth factors are normally used to induce the fate of stem cells into lung organoids;however, these fail to reach maturity. Here, we developed a new methodology to induce the formation of the organoids based on the cell microenvironment. The resulting organoids require less time for development. The initial stage of adult cells can be modulated through culture conditions induce a 3D structure like the adult lung. As such, these organoids have the potential to be used for modeling adult diseases and to develop specific models from patient cells, which is one step forward to personalized medicine. SFTPB is one of the main proteins which facilitates the breathing process. Its high expression into our model may indicate that breathing occurs into our lung organoids. The higher expression of TMPRSS-2 and ACE2 into the organoids has a major significance in the field of virology since both proteins are the mainly entrance of SARS-CoV-2, and influenza H1N1.>.