Schouten, I. | Search bioRxiv

bioRxiv2024

Human adipose-derived mesenchymal stromal cells improved wound healing in enterocutaneous fistulizing disease mouse model

A significant complication of Crohns disease is the formation of perianal fistulas. While local application of human adipose tissue-derived mesenchymal stromal cells (AT-MSC INN Darvadstrocel, Takeda) is an approved therapy for this condition, challenges in studying human clinical tissue and the absence of a robust experimental model have hindered deeper understanding of the preclinical efficacy and mechanisms behind the therapy. We have developed a model that closely mimics the clinical scenario, using human gut tissue transplanted subcutaneously into SCID mice. In this model, enterocutaneous fistulas are reliably induced by combining imiquimod-induced psoriatic dermatitis above the transplant with systemic lipopolysaccharide (LPS), a major component of the bacterial cell wall. Similar to clinical observations, local application of AT-MSC significantly improved fistula wound healing and re-epithelialization. This model system enabled comprehensive tissue harvesting for histopathological analysis, spatial transcriptomics, and protein profiling. Our findings demonstrate that AT-MSC applied around the fistula wound survive for up to three weeks, migrating into the fistula tract and further into the inflamed human gut tissue. Within the fistula tract, AT-MSCs acquired immune-active properties, with increased expression of SOD2 and CCL2, and were associated with a substantial population of M2 macrophages. In contrast, AT-MSC located in healthy tissue near the fistula remained stationary, adopting a fibroblast-like phenotype within a collagen-rich extracellular matrix. These preclinical results support the safety and efficacy of AT-MSC for treating fistulizing gut disease. Furthermore, our data suggest that the inflamed fistula tract acts as a scaffold promoting AT-MSC activity and migration. Enhancing SOD2 and CCL2 expression through pre-activation or genetic modification may further improve the therapeutic potential of these cells.

pathology↗

bioRxiv2021

Hyperinflammation evokes different antiviral TMPRSS2 and ADAM17 expression responses in human gut xenograft versus host mouse gut although overall genomic responses are similar

The global spread of the newly emerged severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the pandemic outbreak of coronavirus disease 2019 (COVID-19), an inflammatory disease that is primarily affecting the respiratory system. However, gastrointestinal symptoms in COVID-19 patients suggests that the gut may present another viral target organ. Disease development and severity is dependent on viral interaction with two cell surface human proteins, ACE2 and TMPRSS2, and on antiviral response which may lead to systemic hyperinflammatory syndrome and multiorgan dysfunction. Understanding the host response to SARS-CoV-2 infection and the pathology of the disease will be greatly enhanced by the development of appropriate animal models. Laboratory mice have been the mainstay of therapeutic and vaccine development, however, the virus does not grow in wild type mice and only induced mild disease in transgenic animals expressing human ACE2. As there are known differences between immune response in laboratory mice and humans we evaluated the response of human gut developed as xenografts and host mouse gut following systemic LPS injections as a hyperinflammation model system. The orthologous gene expression levels in the mouse and human gut were highly correlated (Spearmans rank correlation coefficient: 0.28-0.76) and gene set enrichment analysis of significantly upregulated human and mouse genes revealed that a number of inflammatory and immune response pathways are commonly regulated in the two species. However, species differences were also observed, most importantly, in the inflamed human gut but not in the mouse gut, there was clear upregulation of mRNAs coding for TMPRSS2, ADAM17 and for RIG-I-like receptors, which are involved in the recognition of viruses and in antiviral innate immune response. Moreover, using species-specific immunofluorescence microscopy, we demonstrated the expression and localization of human ACE2 and TMPRSS2 proteins, which are essential elements of the molecular machinery that enables SARS-CoV-2 to infect and replicate in human gut cells. Our findings demonstrate that the intestinal immune response to inflammation in humans and mice are generally very similar. However, certain human-specific diseases, such as COVID-19, can only be successfully studied in an experimental model of human tissue, such as the gut xenograft.

immunology↗