RESUMO
Transplanted stromal cells have demonstrated considerable promise as therapeutic agents in diverse disease settings. Paracrine signaling can be an important mediator of these therapeutic effects at the sites of acute or persistent injury and inflammation. As many stromal cell types, including bone marrow-derived stromal cells (BMSCs), display tissue-specific responses, there is a need to explore their secretory dynamics in the context of tissue and injury type. Paracrine signals are not static, and could encode contextual dynamics in the kinetic changes of the concentrations of the secreted ligands. However, precise measurement of dynamic and context-specific cellular secretory signatures, particularly in adherent cells, remains challenging. Here, by creating an experimental and computational analysis platform, we reconstructed dynamic secretory signatures of cells based on a very limited number of time points. By using this approach, we demonstrate that the secretory signatures of CD133-positive BMSCs are uniquely defined by distinct biological contexts, including signals from injured cardiac cells undergoing oxidative stress, characteristic of cardiac infarction. Furthermore, we show that the mixture of recombinant factors reproducing the dynamics of BMSC-generated secretion can mediate a highly effective rescue of cells injured by oxidative stress and an improved cardiac output. These results support the importance of the dynamic multifactorial paracrine signals in mediating remedial effects of stromal stem cells, and pave the way for stem cell-inspired cell-free treatments of cardiac and other injuries.
Assuntos
Inflamação/genética , Células-Tronco Mesenquimais , Infarto do Miocárdio/genética , Neovascularização Fisiológica/genética , Antígeno AC133/genética , Animais , Medula Óssea/metabolismo , Células da Medula Óssea/metabolismo , Células da Medula Óssea/patologia , Diferenciação Celular/genética , Células Cultivadas , Humanos , Inflamação/metabolismo , Inflamação/patologia , Ligantes , Infarto do Miocárdio/patologia , Infarto do Miocárdio/terapia , Estresse Oxidativo/genética , Comunicação Parácrina/genéticaRESUMO
Direct intercellular transfer of cellular components is a recently described general mechanism of cellcell communication. It is a more non-specific mode of intercellular communication that is not actively controlled by the participating cells. Though membrane bound proteins and small non-protein cytosolic components have been shown to be transferred between cells, the possibility of transfer of cytosolic proteins has not been clearly established, and its mechanism remains unexplained. Using a cellcell pair of metastatic melanoma and endothelial cells, known to interact at various stages during cancer progression, we show that cytosolic proteins can indeed be transferred between heterotypic cells. Using precise relative cell patterning we provide evidence that this transfer depends on extent of the interface between heterotypic cell populations. This result is further supported by a mathematical model capturing various experimental conditions. We further demonstrate that cytosolic protein transfer can have important functional consequences for the tumorstroma interactions, e.g., in heterotypic transfer of constitutively activated BRAF, a common melanoma associated mutation, leading to an enhanced activation of the downstream MAPK pathway. Our results suggest that cytosolic protein transfer can have important consequences for regulation of processes involving physical co-location of heterotypic cell types, particularly in invasive cancer growth.
Assuntos
Comunicação Celular , Células Endoteliais/metabolismo , Células Endoteliais/patologia , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Melanoma/metabolismo , Melanoma/secundário , Linhagem Celular , Técnicas de Cocultura/métodos , Humanos , Melanoma/patologia , Transporte ProteicoRESUMO
TreeSAAP has been used in a variety of protein studies for detecting adaptation in terms of the physicochemical properties involved in amino acid replacement. The accuracy of TreeSAAP was here tested using simulated protein-coding DNA data. A sampling of 1402 simulated amino acid replacements resulted in a default accuracy of 81.1%, with most properties exhibiting >90% accuracy. More than half of the false-positive results were traced to just 11 of the 180 possible single-step amino acid exchanges. Overall accuracy increased as the number of magnitude partitions used in the analysis decreased. Sliding window size did not significantly affect accuracy.