Human Metapneumovirus Infection Modifies Cytoskeletal Architecture and Growth Factors of Mesenchymal Stem Cells.

BACKGROUND

Human metapneumovirus (HMPV) is a leading cause of acute respiratory infection worldwide, and most people over the age of 10 have been infected. Despite its high prevalence, its pathogenesis is not yet fully elucidated. Many cell types, including stem cells, are susceptible to HMPV infection. Our previous results suggested that mesenchymal stem cells (MSCs) are susceptible and permissive to HMPV infection. This study aimed to understand the effects of HMPV on stem cell biology. Specifically, we focused on the expression and localization of cytoskeletal proteins and their role during syncytium formation.

METHODS

To this end, we evaluated the surface markers CD90, CD73, and CD105 in infected and non-infected cells using flow cytometry; assessed infection-induced modifications in cytoskeletal proteins using immunofluorescence, and analyzed changes in the secretion pattern of the growth factors including Ang-2, EGF, EPO, FGF-basic, G-CSF, GM-CSF, HGF, M-CSF, PDGF-AA, PDGF-BB, SCF, TGF-α, and VEGF.

RESULTS

We observed changes in the distribution of tubulin and actin. Annexin V levels were also increased following HMPV infection, likely due to membrane modifications associated with viral fusion during entry and/or viral exit by budding. HMPV infection induced a significant decrease in EGF and VEGF secretion compared with mock-infected cultures. In contrast, Ang-2 and PDGF-AA levels were significantly elevated in infected MSCs.

CONCLUSIONS

HMPV infection alters the structure and surface marker expression of PL-MSCs; however, these cells retain their ability to differentiate into various tissue types. Nevertheless, the virus disrupts growth factor production, creating a complex balance between cellular damage and the remaining potential for tissue repair.