MSC confirmation and patients characteristics
Flow cytometry was performed to identify the immunophenotyping of menstrual blood-derived MSCs, and the expression of CD29, CD73, and CD105 were positive, while CD34, CD45, CD117, and HLA-DR were negative (Fig. S1A). And MSCs can be differentiated into adipogenic, osteogenic, and chondrogenic cells (Fig. S1B), which is the same as our previous studies [24].
The first patient had a history of hypertension for several years and worked in Wuhan for a long time. He insisted on oral nifedipine to control blood pressure. Physical examination showed fever, with a body temperature of 39.6 °C, breathing rate of 19 times per minute, the pulse of 110 times per minute. The partial pressure of oxygen (PO2) is 60.1 mmHg and oxygenation index(PO2 /FiO2) is 120.2 on the basis of 50% fraction of inspiration oxygen (FiO2). The laboratory examination of results showed in Table S1 with an increased leukocyte count (13.60 * 109/l), decreased lymphocytes (0.5 * 109/l), normal hemoglobin (148 g/l). The inflammatory indicator of and the immune indicator which showed in Table S1. The chest computed tomography (CT) indicates large lungs, strands, patches are visible in the two lungs, the border is blurred, part of the paving stones are changed, part of the consolidation, part of the air bronchus signs (Fig. 1A). The patient tested negative for eight common respiratory pathogens, which were respiratory syncytial virus, adenovirus, influenza A virus, Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella pneumophila, parainfluenza virus, and influenza B virus, and the influenza A antigen screening was also negative. Finally, he was diagnosed with COVID-19 based on the rRT-PCR amplification of the viral DNA from a sputum sample. He was transferred to intensive care unit (ICU) because of severe dyspnea at 28 Jan, 2020. The patient was treated with human immunoglobulin on 27 Jan and 28 Jan. During the ICU from 28 Jan to 05 Feb, methylprednisolone, lopinavir and ritonavir tablets, and arbidol were given to the patient. At the same time, the patient received MSC treatment on 28 Jan, 30 Jan and 01 Feb, 2020. After MSC treatment, the symptoms of fever and dyspnea were significantly improved (Fig. 1B). The PO2 is 123 mmHg and PO2/FiO2 is 332.4 even at 37% FiO2 on 5 Feb. Hence, the patient was out of the ICU to the general ward at this day and continue methylprednisolone, lopinavir and ritonavir tablets and arbidol treatment. The dynamic changes of blood routine, oxygenation indicators, coagulation function, inflammatory indicators and immune indicators are shown in Table S2.
The second patient was found to have little rough breaths. Laboratory examinations showed normal leukocytes (9.3*10E9/L), neutrophils (6*10E9/L), and lymphocytes (2.3*10E9/L). The hypersensitive c-reactive protein (CRP) was 10.8 mg/L. The initial chest CT showed a few interstitial changes in both lungs and ground-glass opacities (GGOs) in the subpleural area of the right lower lobe in right long. He was given supportive care, and antiviral treatment with lopinavir and ritonavir, and arbidol. Immunoglobulin (20 g daily) was also administrated to modulate the inflammatory response. From day 2 to 7 of hospitalization, the patient continued to have fever, with a daily maximum temperature in the range of 38-39.5℃. On day 5, the patient complained a headache and began to have an obvious coughing, with PaO2 of 75 mmHg, arterial partial pressure of carbon dioxide (PaCO2) of 33 mmHg, oxygenation index (OI) of 228 mmHg under nasal oxygen breath of 3 L/min. A follow-up chest CT showed an increased density of GGOs in the right lower lobe, which then developed into consolidations with perilobular thickening. Moreover, new patchy shadow appeared in the subpleural area of left lung. Laboratory examination showed almost normal index except increased leukocytes (10.7*10E9/L). Apart from symptom management, the patient received methylprednisolone (40 mg daily). On day 7, the development of high fevers reached 39.4℃ and the patient got oppression in chest. PaO2 of 68 mmHg, PaCO2 of 34 mmHg, OI of 208 mmHg under nasal oxygen breath of 3L/min. The following chest CT showing multifocal peripheral patchy areas of nodular consolidations and GGO lesions were newly developed in the subpleural areas of left lung. Due to the patient’s recurrent fevers and presentation in chest CT, blood cultures were collected on Day 5, whereas have no growth to date. The patient was permitted interferon alpha inhalation and antibiotic therapies of piperacillin-tazobactam based on the previous comprehensive treatments. Then the physical examination revealed a BT decreased to 38.5℃ on Day 11, still accompanied by obvious chest stuffiness and cough with a small amount of sputum expectoration. The Laboratory examination showed sharply increased leukocyte (25.9*10E9/L), neutrophils (23.2*10E9/L), and CRP was 43.5 mg/L. The inflammation cytokines during this time were also significantly increased. IL-6 was 71.5 pg/ml, IL-10 was 7.8 pg/ml, tumour necrosis factor α (TNF-α) 84.3 pg/ml, tumour necrosis factor γ (TNF-γ) was 34.7 pg/ml. Up to day 11, the patient underwent persistent positive SARS-CoV-2 RNA at sputum daily. Given the severe pulmonary injury caused by inflammatory response and side effects, the glucocorticoid and antiviral and antibiotic therapies had been withdrawn. The MSCs adoptive transfer therapy was also proposed under the guidance of the specialist group. Treatment with intravenous MSCs therapy was progressed on hospital at Day 11 (29 Jan), 12 (30 Jan), 14 (1 Feb) respectively. During the following three days, the patient felt improved breathe with intermittent dry cough and decreased chest stuffiness. The physical examination revealed improved clinical condition with an obviously decreased BT of 37.4℃. Owing to the changing clinical presentations, methylprednisolone has been given the half dose (20 mg daily). The subsequent chest CT on day 17 revealed significant absorption of worsening patches infiltrating in both lungs. In the meantime, the result of SARS-CoV-2 RNA test at sputum turned negative for the first time, although a repeated rRT-PCR of SARS-CoV-2 RNA was positive on Day 20. Then the persistent negative results of SARS-CoV-2 RNA both at sputum and stool were confirmed in the following days. The temperature of the patient dropped to normal and the symptoms disappeared. On day 23, the chest CT showed almost absorption of leaving a few fibrous lesions maybe represent residual organizing pneumonia. The laboratory results revealed well-improved leukocyte (14.6*10E9/L), neutrophils (10.4*10E9/L), and levels of inflammation factors. Liver function reflected elevated alanine aminotransferase (ALT = 190 U/L), aspartate aminotransferase (AST = 41 U/L). Given the almost favorable performance of the clinical conditions, on day 24, the patient was discharged.
MSCs improved COVID-19 patients via reducing inflammatory cytokines
We found that after the MSC treatment, the oxygenation indicators (such as FiO2%, PO2, and PO2/FiO2) significantly improved, the immune indicators (including CD4, CD8, T lymphocyte, B lymphocyte, and NK cells) were increased and the inflammation indicators (IL-2, IL-6, IL-10, TNF, IFN) were significantly decreased. Repeat chest CT showed stranded and multiple patchy high-density shadows in both lungs, and the exudation lesions in both lungs are significantly better than before (Fig. 1). Additionally, the fibrosis has obviously decreased after MSC transplantation. Finally, the COVID-19 nucleic acid test turned negative at twice. The patient was out of the hospital at 19 Feb without oxygen inhalation and stop methylprednisolone therapy. However, lopinavir and ritonavir tablets and arbidol were continue given to the patient. We follow up the patient at 26 Feb (one week after discharged from hospital) and found that conventional index was normal (Table S1). At last the patient withdrawal all medications. The detailed CONSORT diagram for the treatment of the patient is presented in Fig. 1.
MSCs attenuated inflammation of pulmonary fibrosis in mice
To investigate the effects of MSCs on BLM-induced pulmonary fibrosis, MSCs carried luciferase were transplanted into mice through tail vein twice a week after BLM administration. Live imaging result showed that BLM-treated group recruited more MenSCs migrated into injured lung compared to untreated group (Fig. S2A), while little expression of human specific-surfactant protein D (SPD) revealed that MenSCs did not differentiate into lung epithelia cells (Fig. S2B). According to the results, BLM group displayed less amounts of epithelia cells compared to control group, while this apoptosis was reduced after MSCs administration (Fig. 2A). These results indicated that MSCs migrated to injured lung indicating an anti-apoptosis effect. H&E staining and Masson staining showed that mice from BLM-induced group caused serious damage in the structure of lung alveoli, a large amount of inflammatory cells infiltration and mass deposition of collagen especially around bronchi and vessels compared to control group (Fig. 2B). Although, alveolar structure, inflammatory cells and collagen deposition were decreased when compared to BLM group post MSCs transplantation (Fig. 2B). Additionally, fibrosis area and modified Ashcroft score evaluation were corresponded to the section observation (Fig. 2C and 2D). MSCs transplantation also increased the dry/wet radio of lung tissues (Fig. 2E). There was significantly increased in collagen deposition in BLM group compared to Control group, while MSCs transplantation showed a decreasing trend of collagen deposition compared to BLM group (Fig. 2F), it was consistent with Masson staining. The body weight of mice in BLM group showed a significant reduction compared to Control group after BLM administration 21 days, and showed a recovery trend after MSCs transplantation (Fig. 2G). These results demonstrated that administration of MSCs improved the symptoms of fibrosis.
According to the cell smears, the number of inflammatory cells were significantly increased in BLM group compared to control group, but it was decreased after MSCs administration (Fig. S3A). Total protein of BALF was increased in BLM group but decreased in MSC group (Fig. S3B and S3C). Meanwhile, the level of BALF inflammatory cytokines showed same trend. After MSCs administration, the level of IL-10, IL-1β,IL-6, TGF-β1 were decreased (Fig. S3D). Additionally, serum concentration of IL-10, IL-1β༌IL-6, TGF-β1 exhibited a same trend as BALF (Fig. S3E). These results indicated that MSCs has a potential effect on immune-regulation for reducing lung inflammation.
MSCs reduced BLM-induced apoptosis and EMT of MLE-12 cells
CCK8 assay showed that MSCs significantly reduced BLM-induced MLE-12 cells injury (Fig. 3A) and MSCs promoted the clonogenic potential of MLE-12 cells compared BLM group (Fig. 3B). Additionally, flow cytometry assay confirmed that co-cultured with MSCs significantly reduced the rate of apoptotic MLE-12 cells (Fig. 3C), and MSCs significantly attenuated BLM-induced cell cycle arrest in G2/M phase (Fig. 3D). These results indicated that MSCs had the anti-apoptosis effect on the proliferation of MLE-12 cells after treated with BLM. To assess whether MSCs has an impact on BLM-induced EMT, we investigated the expression of EMT-related proteins. Immunoflurescence assay showed that E-cadherin significantly increased after coculture with MSCs, while N-cadherin significantly decreased (Fig. 3E). Furthermore, wounding healing assay and invasion assay showed that the ability of migration and invasion of BLM-treated MLE-12 cells was significantly inhibited by MSC (Fig. 3F). These results suggested that MSCs has a potential effect in inhibiting EMT in MLE-12 cells.
MSCs relieved BLM-induced pulmonary fibrosis through anti-inflammatory and anti-apoptotic effects
We used an antibody array to examine cytokine levels in the supernatants. PCA analysis showed little differences in the same group, and different groups can be distinguished by a large separation (Fig. 4A). As shown in Fig. 4B, several cytokines (i.e., RANTES, GM-CSF, MIG-1 g, MCP-5, Eotaxin) were significantly decreased; while OPG, FetuinA, Dkk-1, Renin-1 were highly expressed. Go and KEGG pathway showed that inflammation factors chemotaxis and cytokine-cytokine receptor interaction pathway may be the most important pathway (Fig. 4C and 4D). Furthermore, RNA-Seq was performed on the Illumina Hiseq platform. A total of 2503 genes were found to be significantly differential expressed between Control and BLM group, and 252 significantly differential expressed genes between BLM and MenSC group (Fig. 5A). Among them, 955 genes were found to be up-regulated and 1549 genes down-regulated between Control and BLM group, and 188 genes were found to be up-regulated and 64 genes down-regulated between BLM and MenSC group (Fig. 5B). GO and KEGG analysis showed that apelin signaling pathway, focal adhesion, and NF-kappa B signaling are related to the development of fibrosis (Fig. 5C and 5D). Additionally, a-SMA, CTGF and cdh1 were related to fibrosis in the apelin signaling pathway (Fig. S4).
As expected, IHC result showed that, after MSCs transplantation, the expression of TGF-β1, CTGF, a-SMA protein significantly decreased while the expression of E-cadherin was increased compared to BLM group (Fig. 6A). We also measured the expression of upstream protein, results showed that MSC transplantation reduced the expression of phosphorylation of Smad3 (Fig. 6B), although phosphorylation of Smad2 and Smad4 has no significant difference (data not shown). Moreover, Bcl2/Bax/active caspase-3 were considered as the apoptosis-related protein. As shown in Fig. 6B, MSCs treatment resulted in a significant increase of Bcl2 and decrease of BAX and active caspase-3 compared to BLM group. According to these results, we speculated that MSCs has an anti-apoptosis effect to reduce BLM induced pulmonary fibrosis.