Enriched protein screening of human bone marrow mesenchymal stromal cell secretions reveals MFAP5 and PENK as novel IL-10 modulators

The secreted proteins from a cell constitute a natural biologic library that can offer significant insight into human health and disease. Discovering new secreted proteins from cells is bounded by the limitations of traditional separation and detection tools to physically fractionate and analyze samples. Here, we present a new method to systematically identify bioactive cell-secreted proteins that circumvent traditional proteomic methods by first enriching for protein candidates by differential gene expression profiling. The bone marrow stromal cell secretome was analyzed using enriched gene expression datasets in combination with potency assay testing. Four proteins expressed by stromal cells with previously unknown anti-inflammatory properties were identified, two of which provided a significant survival benefit to mice challenged with lethal endotoxic shock. Greater than 85% of secreted factors were recaptured that were otherwise undetected by proteomic methods, and remarkable hit rates of 18% in vitro and 9% in vivo were achieved

Recovery of warm ischemic rat liver grafts by normothermic extracorporeal perfusion

Liver transplantation is currently the only established treatment of end-stage liver disease, but it is limited by a severe shortage of viable donor livers. Donors after cardiac death (DCD) are an untapped source that could significantly increase the pool of available livers. Preservation of these DCD livers by conventional static cold storage (SCS) is associated with an unacceptable risk of primary nonfunction and delayed graft failure. Normothermic extracorporeal liver perfusion (NELP) has been suggested as an improvement over SCS. Livers recovered from male Lewis rats were subjected to 1 hr of warm ischemia and preserved with 5 hr of SCS or NELP, and transplanted into syngeneic recipients. As additional controls, non-ischemic livers preserved with 6 hr of SCS or NELP and unpreserved ischemic livers were transplanted. After NELP, ischemically damaged livers could be orthotopically transplanted into syngeneic recipients with 92% survival (n=13) after 4 weeks, which was comparable with control animals that received healthy livers preserved by SCS (n=9) or NELP (n=11) for 6 hr. On the other hand, animals from ischemia/SCS control group all died within 12 hr postoperatively (n=6). Similarly, animals that received ischemic livers without preservation all died within 24 hr after transplantation (n=6). These results suggest that NELP has the potential to reclaim warm ischemic livers that would not be transplantable otherwise. The rat model in this study is a useful platform to further optimize NELP as a method of recovery and preservation of DCD livers

Aire controls mesenchymal stem cell-mediated suppression in chronic colitis

Mesenchymal stem cells (MSCs) are emerging as a promising immunotherapeutic, based largely on their overt suppression of T lymphocytes under inflammatory and autoimmune conditions. While paracrine cross-talk between MSCs and T cells has been well-studied, an intrinsic transcriptional switch that programs MSCs for immunomodulation has remained undefined. Here we show that bone marrow-derived MSCs require the transcriptional regulator Aire to suppress T cell-mediated pathogenesis in a mouse model of chronic colitis. Surprisingly, Aire did not control MSC suppression of T cell proliferation in vitro. Instead, Aire reduced T cell mitochondrial reductase by negatively regulating a proinflammatory cytokine, early T cell activation factor (Eta)-1. Neutralization of Eta-1 enabled Aire(−/−) MSCs to ameliorate colitis, reducing the number of infiltrating effector T cells in the colon, and normalizing T cell reductase levels. We propose that Aire represents an early molecular switch imposing a suppressive MSC phenotype via regulation of Eta-1. Monitoring Aire expression in MSCs may thus be a critical parameter for clinical use