Secretome-Mediated Neuroprotective Effects of the hiPSC-derived Glial and Neuronal Progenitor Cells in the Hypoxia-Induced Neuronal Damage (Comparative Study)

Background: Stem cell secretomes hold great promise for regenerative medicine. This study is focused on the secretome-mediated neuroprotective effects of the human induced pluripotent stem cell-derived neuronal and glial progenitor cells. Therapeutic properties of the secretomes were assessed under conditions of the hypoxia-induced neuronal damage in vitro and in vivo. Methods: Secretory activity of the cultured neuronal and glial progenitor cells was analyzed by proteomic and immunosorbent-based approaches. Conditioned media collected from the cultures was tested for neuroprotective properties in vitro and in vivo.In vitro experiments involved exposure of SH-SY5Y cells to the conditioned media during the recovery from the cobalt chloride-induced hypoxia. Neuroprotective effects were assessed by cell survival and neurite outgrowth. Cell survival indicators included MTT and LDH tests, vital staining with propidium iodide and Hoechst 33342, and polymerase chain reaction assay for the expression of apoptosis-related genes. Neurite outgrowth was assessed by alterations in SH-SY5Y cell morphology and MAP2/GAP43 gene expression dynamics. In vivo experiments involved intra-arterial administration of the conditioned media to laboratory rats during the recovery from experimental ischemic stroke. Neuroprotective effects were assessed by overall survival, neurologic deficit and infarct volume dynamics, as well as by the end-point values of the apoptosis- and inflammation-related gene expression levels, the extent of microglia/macrophage infiltration, and the numbers of newly formed blood vessels in the affected area of the brain. Results: Secretomes of glial and neuronal progenitor cells partially overlapped, with specific proteins (found in secretome of one of the studied cultures and absent from the other) constituting, respectively, 31% and 45%. The glial progenitor cell-conditioned media showed higher content of neurotrophins (BDNF, GDNF, CNTF and NGF).Moreover, the glial progenitor cell-conditioned media was superior to the neuronal progenitor cell-conditioned media in facilitating neurite outgrowth and increasing SHSY-5Y cell survival after the cobalt dichloride-induced hypoxia. In addition, intra-arterial infusion of the glial progenitor cell-conditioned media to the animals after experimental ischemic stroke significantly enhanced functional recovery and promoted tissue repair at the site of brain damage, as indicated by reduced microglia/macrophage infiltration, decreased expression of pro-apoptotic gene Bax and pro-inflammatory cytokine gene Tnf, increased expression of anti-inflammatory cytokine genes (Il4, Il10, Il13), and increased numbers of newly formed blood vessels within the damaged area. None of these effects were exerted by the neuronal progenitor cell-conditioned media. Conclusions: The results indicate pronounced cytoprotective, anti-inflammatory and angionenic properties of soluble factors secreted by glial progenitor cells.