Bioengineered Human Pyloric Sphincters Using Autologous Smooth Muscle and Neural Progenitor Cells.

Gastroparesis leads to inadequate emptying of the stomach resulting in severe negative health impacts. Appropriate long-term treatments for these diseases may require pyloric sphincter tissue replacements that possess functional smooth muscle cell (SMC) and neural components. This study aims to bioengineer, for the first time, innervated human pylorus constructs utilizing autologous human pyloric sphincter SMCs and human neural progenitor cells (NPCs). Autologous SMCs and NPCs were cocultured in dual-layered hydrogels and formed concentrically aligned pylorus constructs. Innervated autologous human pylorus constructs were characterized through biochemical and physiologic assays to assess the phenotype and functionality of SMCs and neurons. SMCs within bioengineered human pylorus constructs displayed a tonic contractile phenotype and maintained circumferential alignment. Neural differentiation within bioengineered constructs was verified by positive expression of ßIII-tubulin, neuronal nitric oxide synthase (nNOS), and choline acetyltransferase (ChAT). Autologous bioengineered innervated human pylorus constructs generated a robust spontaneous basal tone and contracted in response to potassium chloride (KCl). Contraction in response to exogenous neurotransmitter acetylcholine (ACh), relaxation in response to vasoactive intestinal peptide (VIP), and electrical field stimulation (EFS) were also observed. Neural network integrity was demonstrated by inhibition of EFS-induced relaxation in the presence of a neurotoxin or nNOS inhibitors. Partial inhibition of ACh-induced contraction and VIP-induced relaxation following neurotoxin treatment was observed. These studies provide a proof of concept for bioengineering functional innervated autologous human pyloric sphincter constructs that generate a robust basal tone and contain circumferentially aligned SMCs, which display a tonic contractile phenotype and functional differentiated neurons. These autologous constructs have the potential to be used as (1) functional replacement organs and (2) physiologically relevant models to investigate human pyloric sphincter disorders.

Pancreatic Cancer Cells Isolated from Muc1-Null Tumors Favor the Generation of a Mature Less Suppressive MDSC Population.

Mucin 1 (MUC1) is a transmembrane mucin glycoprotein that is over-expressed and aberrantly glycosylated in >80% of human pancreatic ductal adenocarcinoma (PDA) and is associated with poor prognosis. To understand the role of MUC1 in PDA, we have recently developed two mouse models of spontaneous PDA, one that expresses full-length human MUC1 transgene (KCM mice) and one that is null for MUC1 (KCKO mice). We have previously reported that KCM mice express high levels of myeloid derived suppressor cells (MDSCs) in their tumors and develop highly aggressive PDA. To further understand the underlying mechanism for high MDSC levels in KCM-tumors, we generated primary cell lines from KCM and KCKO-tumors. In this study, we report that MDSCs derived using KCM cells express significantly higher levels of arginase 1 and inducible nitric oxide synthase (markers associated with immune suppression) and lower levels of CD115 (a marker associated with maturation of myeloid cells) as compared to KCKO-derived MDSCs. Functionally, KCM-derived MDSCs secrete significantly higher levels of urea and nitric oxide (NO) when co-cultured with normal splenic cells as compared to KCKO-derived MDSCs. Data indicates that KCM-derived MDSCs remain immature and are more suppressive as compared to KCKO-derived MDSCs. This was further corroborated in vivo where MDSCs isolated from KCM-tumor-bearing mice retained their immature state and were highly suppressive as compared to MDSCs derived from KCKO-tumor-bearing mice. Finally, we show that KCM cells secrete significantly higher levels of prostaglandin E2 (PGE2), a COX-2 metabolite and a known driver of suppressive MDSCs as compared to KCKO cells. Thus, inhibiting PGE2 with a specific COX-2 inhibitor reverses the immunosuppressive and immature phenotype of KCM-derived MDSCs. This is the first report that clearly suggests a functional role of pancreatic tumor-associated MUC1 in the development of functional MDSCs.

Soluble tumor necrosis factor receptors shed by breast tumor cells inhibit macrophage chemotaxis.

Breast tumor cells alter their microenvironment in part through the expression of protumor molecules that influence macrophages during tumor progression and metastasis. Macrophage recruitment is stimulated by chemotactic factors, including tumor necrosis factor alpha (TNF-α), which also stimulates the cytotoxic/tumor cell killing macrophage phenotype. Through TNF-α converting enzyme (TACE/ADAM17) activities, breast tumor cells shed membrane-bound proteins, including their TNF receptors (sTNFR1/2), which serve as decoys sequestering TNF-α and preventing TNF-α-driven apoptosis of tumor cells, thereby decreasing TNF-α bioavailability. Here we investigated the levels of sTNFRs shed by breast tumor cells and determined the effects of shed sTNFRs on macrophage migration toward TNF-α. TNF-α and sTNFRs concentrations were measured in murine normal epithelial, stromal, and mammary tumor cells. The migration of murine macrophages towards TNF-α in the presence of tumor derived soluble factors (TDSFs) shed by TACE was determined. TNF-α concentrations secreted by tumor and normal epithelial cells were below the detection limit contrasting with stromal cells, especially macrophages, which expressed higher levels of TNF-α (P<0.001). Regardless of the cell tested, treatment with the TACE inhibitor TAPI-0 led to a significant decrease in sTNFR2 shed (P<0.05). The dose-dependent macrophage migration toward TNF-α prevented by incubation with TDSFs was not observed with TDSFs collected following TAPI-0 treatment (P<0.05). Furthermore, the TNF-α-driven increased pAkt expression in macrophage was inhibited by TACE shed TDSFs (P<0.05). These results highlight the role of tumor-shed sTNFRs in TNF-α -driven macrophage chemotaxis.