Gastrointestinal Manifestations of COVID-19 Infection: Clinicopathologic Findings in Intestinal Resections Performed at Single Institution

Three-Dimensional Cell Cultures: The Bridge between In Vitro and In Vivo Models

Although historically, the traditional bidimensional in vitro cell system has been widely used in research, providing much fundamental information regarding cellular functions and signaling pathways as well as nuclear activities, the simplicity of this system does not fully reflect the heterogeneity and complexity of the in vivo systems. From this arises the need to use animals for experimental research and in vivo testing. Nevertheless, animal use in experimentation presents various aspects of complexity, such as ethical issues, which led Russell and Burch in 1959 to formulate the 3R (Replacement, Reduction, and Refinement) principle, underlying the urgent need to introduce non-animal-based methods in research. Considering this, three-dimensional (3D) models emerged in the scientific community as a bridge between in vitro and in vivo models, allowing for the achievement of cell differentiation and complexity while avoiding the use of animals in experimental research. The purpose of this review is to provide a general overview of the most common methods to establish 3D cell culture and to discuss their promising applications. Three-dimensional cell cultures have been employed as models to study both organ physiology and diseases; moreover, they represent a valuable tool for studying many aspects of cancer. Finally, the possibility of using 3D models for drug screening and regenerative medicine paves the way for the development of new therapeutic opportunities for many diseases.

The spectrum of pneumatosis intestinalis in the adult. A surgical dilemma

Pneumatosis intestinalis (PI) is a striking radiological diagnosis. Formerly a rare diagnostic finding, it is becoming more frequently diagnosed due to the wider availability and improvement of computed tomography scan imaging. Once associated only with poor outcome, its clinical and prognostic significance nowadays has to be cross-referenced to the nature of the underlying condition. Multiple mechanisms of pathogenesis have been debated and multiple causes have been detected during the years. All this contributes to creating a broad range of clinical and radiological presentations. The management of patients presenting PI is related to the determining cause if it is identified. Otherwise, in particular if an association with portal venous gas and/or pneumoperitoneum is present, the eventual decision between surgery and non-operative management is challenging, even for stable patients, since this clinical condition is traditionally associated to intestinal ischemia and consequently to pending clinical collapse if not treated. Considering the wide variety of origin and outcomes, PI still remains for surgeons a demanding clinical entity. The manuscript is an updated narrative review and gives some suggestions that may help make the decisional process easier, identifying patients who can benefit from surgical intervention and those who can benefit from non-operative management avoiding unnecessary procedures.

The Spectrum of Digestive Tract Histopathologic Findings in the Setting of Severe Acute Respiratory Syndrome Coronavirus-2 Infection: What Pathologists Need to Know

Although the novel severe acute respiratory syndrome coronavirus-2 is known primarily to affect the respiratory system, current evidence supports its capability to infect and induce gastrointestinal tract injury. Data describing the histopathologic alterations of the digestive system in patients infected with severe acute respiratory syndrome coronavirus-2 are becoming more detailed, as the number of studies is increasing and the quality of our insight into the infection and the histopathologic findings is improving. This review highlights the range of pathologic findings that could be observed in gastrointestinal specimens from patients infected with coronavirus disease 2019 and the potential underlying pathogenetic mechanisms of this disease.