Summary Within the gastrointestinal stem cell niche, nerves help to regulate both normal and neoplastic stem cell dynamics. Here, we reveal the mechanisms underlying the cancer-nerve partnership. We find that Dclk1+ tuft cells and nerves are the main sources of acetylcholine (ACh) within the gastric mucosa. Cholinergic stimulation of the gastric epithelium induced nerve growth factor (NGF) expression, and in turn NGF overexpression within gastric epithelium expanded enteric nerves and promoted carcinogenesis. Ablation of Dclk1+ cells or blockade of NGF/Trk signaling inhibited epithelial proliferation and tumorigenesis in a muscarinic acetylcholine receptor-3 (M3R)-dependent manner, in part through suppression of Yes-Associated Protein (YAP) function. This feed-forward ACh-NGF axis activates the gastric cancer niche and offers a compelling target for tumor treatment and prevention.

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Summary The existence of adult pancreatic progenitor cells has been debated. While some favor the concept of facultative progenitors involved in homeostasis and repair, neither a location nor markers for such cells have been defined. Using genetic lineage tracing, we show that Doublecortin like kinase-1 (Dclk1) labels a rare population of long-lived, quiescent pancreatic cells. In vitro, Dclk1+ cells proliferate readily and sustain pancreatic organoid growth. In vivo, Dclk1+ cells are necessary for pancreatic regeneration following injury and chronic inflammation. Accordingly, their loss has detrimental effects after cerulein-induced pancreatitis. Expression of mutant Kras in Dclk1+ cells does not affect their quiescence or longevity. However, experimental pancreatitis converts Kras mutant Dclk1+ cells into potent cancer initiating cells. As a potential effector of Kras, Dclk1 contributes functionally to the pathogenesis of pancreatic cancer. Taken together, Dclk1 marks quiescent pancreatic progenitors that are candidates for the origin of pancreatic cancer.

Chaperone-mediated autophagy (CMA), a cellular process that contributes to protein quality control through targeting of a subset of cytosolic proteins to lysosomes for degradation, undergoes a functional decline with age. We have used a mouse model with liver-specific defective CMA to identify changes in proteostasis attributable to reduced CMA activity in this organ with age. We have found that other proteolytic systems compensate for CMA loss in young mice which helps to preserve proteostasis. However, these compensatory responses are not sufficient for protection against proteotoxicity induced by stress (oxidative stress, lipid challenges) or associated with aging. Livers from old mice with CMA blockage exhibit altered protein homeostasis, enhanced susceptibility to oxidative stress and hepatic dysfunction manifested by a diminished ability to metabolize drugs, and a worsening of the metabolic dysregulation identified in young mice. Our study reveals that while the regulatory function of CMA cannot be compensated for in young organisms, its contribution to protein homeostasis can be handled by other proteolytic systems. However, the decline in the compensatory ability identified with age explains the more severe consequences of CMA impairment in older organisms and the contribution of CMA malfunction to the gradual decline in proteostasis and stress resistance observed during aging.

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Burn injuries have been reported to be an important cause of morbidity and mortality and they are still considered as unmet clinical need. Although there is a myriad of effective stem cells that have been suggested for skin regeneration, there is no one ideal scaffold. The aim of this study was to develop a three-dimensional (3D) bi-layer scaffold made of biological decellularized human amniotic membrane (AM) with viscoelastic electrospun nanofibrous silk fibroin (ESF) spun on top. The fabricated 3D bi-layer AM/ESF scaffold was submerged in ethanol to induce β-sheet transformation as well as to get a tightly coated and inseparable bi-layer. The biomechanical and biological properties of the 3D bi-layer AM/ESF scaffold were investigated. The results indicate significantly improved mechanical properties of the AM/ESF compared with the AM alone. Both the AM and AM/ESF possess a variety of suitable adhesion cells without detectable cytotoxicity against adipose tissue-derived mesenchymal stem cells (AT-MSCs). The AT-MSCs show increased expression of two main pro-angiogenesis factors, vascular endothelial growth factor and basic fibroblast growth factor, when cultured on the AM/ESF for 7 days, when comparing with AM alone. The results suggest that the AM/ESF scaffold with autologous AT-MSCs has excellent cell adhesion and proliferation along with production of growth factors which serves as a possible application in a clinical setting for skin regeneration.

The aim of this study is to develop a simple and cost-effective method for decellularization and preservation of human amniotic membrane (HAM) as a soft tissue replacement and a delivery system for stem cells. The HAM is decellularized (D) using new chemical and mechanical techniques. The decellularization scaffold is evaluated histologically and fully characterized. The cell adhesion and proliferation on the scaffold are also investigated and the biocompatibility of D tissues is evaluated in vivo. The histological studies reveal that the cells are successfully removed from the D tissue. The DNA extraction shows more than 95% cell removal (p = 0.001). The in vitro results indicate that the decellularisation process does not deteriorate the mechanical properties of the tissue, whereas it increases the in vitro biodegradation value (p < 0.05). In the D samples, there is no significant cytotoxicity, and no changes are found in the rate of cell proliferation (p > 0.05). Immunohistochemistry staining indicates that all the tested components remain unchanged within the D tissues. The count of inflammatory cells show that the decellularization process slightly increases the biocompatibility of the tissue after 7 days post-surgery. The results indicate that scaffold proves to be reproducible, rapid, and cost-effective, with a potential role for clinical application.