Human Umbilical Cord Mesenchymal Stem Cells for Adjuvant Treatment of a Critically Ill COVID-19 Patient: A Case Report

Background

The COVID-19 has become a global public health emergency since patients were first detected in Wuhan, China, in December 2019, which spread quickly to 211 countries worldwide and presented a serious threat to public health.¹ It is mainly characterized by fever, dry cough, shortness of breath and dyspnea.² Currently, there are no satisfying antiviral medications and vaccines available. Hence, there is an unmet need of a safe and effective treatment for COVID-19 patients, especially the critically ill cases.

Recently, some clinical researches on the COVID-19 suggested that various inflammatory cells’ infiltration and inflammatory cytokines’ secretion were found in patients’ lungs, alveolar epithelial cells and capillary endothelial cells were damaged, causing acute lung injury.^1,3 So it is suggested that inhibiting inflammatory response maybe the key way to cure the COVID-19. The first step of the SARS-CoV-2 pathogenesis is that the virus specifically recognizes the angiotensin I converting enzyme 2 receptor (ACE 2) by its spike Protein.^3,4 This receptor is abundant in lung and small intestinal tissues, but is also highly expressed in vascular endothelial cells and smooth muscle cells in almost all organs, including the nervous system and skeletal muscle.⁵ Therefore, when the initial symptom is discomfort of other systems in the early stage, it is often easy to be misdiagnosed and delay treatment.

Mesenchymal stem cells (MSCs) are widely used in basic research and clinical application. MSCs, owing to their powerful immunomodulatory ability, may have beneficial effects on preventing or attenuating the cytokine storm. They proved to migrate to damaged tissues, exert anti-inflammatory and immunoregulatory functions, promote the regeneration of damaged tissues and inhibit tissue fibrosis.^6–8 MSCs could secrete many types of cytokines by paracrine secretion or make direct interactions with immune cells, leading to immunomodulation.^9,10 They significantly reduced acute lung injury in mice caused by H9N2 and H5N1 viruses by reducing the levels of proinflammatory cytokines and the recruitment of inflammatory cells into the lungs.¹⁰ MSCs also can secretion MSC-secretome, made of free-soluble protein and EVs, emerges as a promising cell-free therapeutic tool for the treatment of acute and chronic lung diseases, as it displays anti-inflammatory, immunomodulatory, regenerative, pro-angiogenic and anti-protease properties.^11–13 MSC-secretome formulated as a freeze-dried powder and administered by intravenous injection (or inhalation), may represent a well-suited approach for the treatment of patients with COVID-19 pneumonia, especially for the ones in critically severe condition.¹² Compared with MSCs from other sources, UC-MSCs have been widely applied to various diseases due to their convenient collection, no ethical controversy, low immunogenicity, and rapid proliferation rate.^14,15

Here, we introduce a COVID-19 case of a critically ill male patient in China. Then we explore the safety and effectiveness of UC-MSC treatment and provide a new potential means for COVID-19.

Case Presentation

A 48-year-old male patient with COVID-19 without previous medical history. The patient developed a cough with a small amount of white sticky sputum on January 21, 2020. On January 31, he underwent Chest computerized tomography (CT) images in Wuhan Yangtze River Shipping General Hospital, and showed ground glass opacity in both lungs, which indicated that he had a bilateral pulmonary infectious disease. On February 1, he developed fever, with the highest body temperature of 39.2°C, so he received treatment in Tongji Hospital Sino-French New City Campus for 2 days, this patient was not confirmed as COVID-19, he was treated with routine bacterial pneumonia. On February 3, the nucleic acid test was confirmed he was diagnosed as COVID-19, and the patient was admitted to our hospital on February 4. On admission, his temperature was 38.4°C while other vital signs were normal. Meanwhile, on February 4, he showed higher than abnormal levels of neutrophil (NEU) ratio (90.7%), aspartate aminotransferase (AST) (89.9 U/L), alanine transaminase (ALT) (100 U/L), blood urea nitrogen (Bun) (8.41 mmol/L), indicators of inflammation C-reactive protein (CRP) (150 mg/L) and procalcitonin (PCT) (0.766 ng/mL). At the same time, the patient had low blood oxygen saturation (SpO₂: 90%), so the nasal catheter was given oxygen with a flow rate of 3 L/min.

On February 6, the patient’s SpO₂ fluctuated at 75–80%, and the asthmatic chest tightness was obvious in the quiet state. Then he was given noninvasive ventilator (FiO₂: 100%) to assist ventilation, and the SpO₂ rose to 91%.

On February 7, NEU and NEU rate increased to 6.32×10⁹/L and 94.2%, respectively. The concentrations of Bun (10.47 mmol/L) and D-dimer (15.46 μg/mL) were higher than 3 days ago.

On February 7, the patient was confirmed as critically ill COVID-19, presenting with acute respiratory distress, multiple organ injury (hepatic respiratory system), immunosuppression and other symptoms. These resulted suggested that the current therapy was not effective, considering the severe organ damage caused by the inflammatory response and side effects, the adoptive transfer therapy of UC-MSCs was proposed under the recommendation and guidance of the expert group.

Cell transplantation: The clinical grade UC-MSCs were supplied for free by Shanghai University, Qingdao Co-orient Watson Biotechnology group co. LTD and the Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences. The cell product has been certified by the National Institutes for Food and Drug Control of China (authorization number: 2004L04792, 2006L01037, CXSB1900004). Before the intravenous drip, UC-MSCs were suspended in 100 mL of normal saline, and the dosage was calculated by 1 × 10⁶ cells per kilogram of weight. The injection was performed about one hour with a speed of ~25 drops per minute. Antibiotics were discontinued on the day of UC-MSC input, and the rest of the treatment remained unchanged.

The patient was assessed by the investigators through the 14-day observation after UC-MSC treatment. The clinical laboratory and radiological outcomes were recorded and certified by a trained group of doctors.

First, we summarized the symptoms and treatment of the critically ill COVID-19 patient. In Figure 1, the patient was admitted with fever, cough, sputum, dyspnea, poor appetite, poor mental state and fatigue. After the UC-MSC transfusion, no obvious side effects were observed, indicating it was well tolerated. On February 9, the patient’s SpO₂ returned to the normal level (95%). On February 13, the patient tried to take off the ventilator. After the weaning, the patient’s condition was stable and the SpO₂ remained stable at the normal level. At the same time, the cough symptoms of the patient were relieved after treatment, and there was no sputum when coughing.

Figure 1 The major symptoms and treatment of this critically ill COVID-19 patient. Light color indicates mild symptoms, while dark color indicates severe symptoms.

The clinical laboratory features of the patient are shown in Table 1. The number of NEU returned to normal on 20 February (5.88 × 10⁹/L). The number of lymphocyte was 0.23 × 10⁹/L on February 7, gradually recovered after intravenous injection of UC-MSCs, and returned to normal on February 20 (1.32 × 10⁹/L). Before February 9, AST and ALT levels were higher, and on February 17, both decreased to normal (AST: 18.3 U/L, ALT: 46.4 U/L). BUN also decreased gradually from 10.47 mmol/L on February 7, and returned to the normal of 6.01 mmol/L on February 12, which decreased by half. CRP gradually decreased from 150 mg/L before treatment, and returned to the normal level of 1.28 mg/L on February 20. PCT decreased from 0.766 ng/mL to 0.024 ng/mL, returned to normal level. The patient’s throat swab tested positive for the novel coronavirus nucleic acid on 9 February and negative on 20 February.

Table 1 The Clinical Laboratory Characteristics of This Critically Ill COVID-19 Patient

The CT and X-ray are shown in Figure 2. On February 4, CT showed multiple patchy ground glass density shadows, blurred boundary, and severe pulmonary fibrosis in double lungs. CT showed that the ground-glass opacity and pneumonia infiltration had obviously reduced on the 7th day after UC-MSC transplantation. The SpO₂ increased to the normal range after UC-MSC transplantation 2 days, and the non-invasive ventilator was successfully removed after 6 days.

Figure 2 CT and X-ray images of this critically ill COVID-19 patient.

From Table 2, the percentages of various types of lymphocytes in the patient were within the normal range, but the absolute number of lymphocytes had been at a low level. After the UC-MSC reinfusion treatment, the absolute number of lymphocytes increased to a certain extent, from 201/μL to 330/μL on the second day after treatment, and to 651/μL one week later. On February 7, the total absolute number of T lymphocytes was 152/μL, rose to 251/μL on February 9, and 547/μL on February 15. The absolute number of B lymphocytes increased from 21.8/μL to 46.8/μL, while the absolute number of NK cells increased from 17.9/μL to 29.3/μL. After the UC-MSC adjuvant treatment, the absolute number of lymphocytes of the patient was significantly increased. Thus, we speculated that UC-MSCs might adjust the body’s immune function, to improve inflammatory reaction, improve lung function and multiple organ functions to improve the outcome of this critically ill patient.

Table 2 Lymphocyte Subpopulation Analysis of This Critically Ill COVID-19 Patient

Conclusions

The patient with COVID-19 was a 48-year-old man without previous medical history. This hospitalization was due to the infection of SARS-CoV-2. This was a typical case of COVID-19. If the low SpO₂ could not be corrected in time, the patient might die at any time. From Table 2, the percentages of various types of lymphocytes in the patient were within the normal range, but the absolute number of lymphocytes had been at a low level. After the UC-MSC adjuvant treatment, the absolute number of lymphocytes of the patient was significantly increased. Thus, we speculated that UC-MSCs might adjust the body’s immune function, to improve inflammatory reaction, improve lung function and multiple organ functions to improve the outcome of this critically ill patient.

We proposed that the adoptive transfer therapy of UC-MSCs might be an ideal choice to be used. Although only one case was shown here, it would also be very important to inspire more similar clinical practice to treat such critically ill COVID-19 patients.