The present study aimed to investigate whether co-administration of mesenchymal stromal cells (MSC) and
linezolid (LZD) into a rabbit model of methicillin-resistant Staphylococcus aureus (MRSA)-infected
pneumonia would bring a synergistic
therapeutic effect. Human umbilical cord-derived MSCs (hUMSCs) were isolated and characterized. A rabbit model of
pneumonia was constructed by delivering 1 × 1010 CFU MRSA via a
bronchoscope into the basal segment of lower lobe of right lung. Through analyzing vital sign, pulmonary auscultation, SpO2, chest imaging, bronchoscopic manifestations, pathology, neutrophil percentage, and inflammatory factors, we verified that a rabbit model of MRSA-induced
pneumonia was successfully constructed. Individual treatment with LZD (50 mg/kg for two times/day) resulted in improvement of
body weight, chest imaging, bronchoscopic manifestations, histological parameters, and
IL-10 concentration in plasma (P<0.01), decreasing pulmonary auscultation, and reduction of
IL-8,
IL-6, CRP, and TNF-α concentrations in plasma (P<0.01) compared with the
pneumonia model group at 48 and 168 h. Compared with LZD group, co-administration of hUMSCs (1 × 106/kg for two times at 6 and 72 h after MRSA instillation) and LZD further increased the
body weight (P<0.05). The changes we observed from chest imaging, bronchoscopic manifestations and pathology revealed that co-administration of hUMSCs and LZD reduced
lung inflammation more significantly than that of LZD group. The plasma levels of
IL-8,
IL-6, CRP, and TNF-α in combined group decreased dramatically compared with the LZD group (P<0.05). In conclusion, hUMSCs administration significantly improved
therapeutic effects of LZD on
pneumonia resulted from MRSA
infection in a rabbit model.