Cell-based Therapy for Perianal Fistulising Crohn's Disease

Vascular endothelial growth factor secretion and immunosuppression are distinct potency mechanisms of human bone marrow mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) are investigated as cellular therapeutics for inflammatory bowel diseases and associated perianal fistula, although consistent efficacy remains a concern. Determining host factors that modulate MSCs' potency including their secretion of angiogenic and wound-healing factors, immunosuppression, and anti-inflammatory properties are important determinants of their functionality. We investigated the mechanisms that regulate the secretion of angiogenic and wound-healing factors and immune suppression of human bone marrow MSCs. Secretory analysis of MSCs focusing on 18 angiogenic and wound-healing secretory molecules identified the most abundancy of vascular endothelial growth factor A (VEGF-A). MSC viability and secretion of other angiogenic factors are not dependent on VEGF-A secretion which exclude the autocrine role of VEGF-A on MSC's fitness. However, the combination of inflammatory cytokines IFNγ and TNFα reduces MSC's VEGF-A secretion. To identify the effect of intestinal microvasculature on MSCs' potency, coculture analysis was performed between human large intestine microvascular endothelial cells (HLMVECs) and human bone marrow-derived MSCs. HLMVECs do not attenuate MSCs' viability despite blocking their VEGF-A secretion. In addition, HLMVECs neither attenuate MSC's IFNγ mediated upregulation of immunosuppressive enzyme indoleamine 2,3-dioxygenase nor abrogate suppression of T-cell proliferation despite the attenuation of VEGF-A secretion. We found that HLMVECs express copious amounts of endothelial nitric oxide synthase and mechanistic analysis showed that pharmacological blocking reverses HLMVEC-mediated attenuation of MSC's VEGF-A secretion. Together these results suggest that secretion of VEGF-A and immunosuppression are separable functions of MSCs which are regulated by distinct mechanisms in the host.

Perianal disease: Updates and controversies in closing the gaps

Perianal complications are common and morbid in children with Crohn's disease. In this review, we describe the epidemiology, the presentation and diagnosis, evaluation and management. We focus on updates such as the increasing frequency of biologic medications and MRI for evaluation. We also highlight controversies on the timing and approaches to surgical techniques. Finally, perianal disease requires the coordination of multidisciplinary care with nursing, radiology, gastroenterology, and surgery to optimize outcomes - both medical and patient-centered.

Modern surgical strategies for perianal Crohn's disease

One of the most challenging phenotypes of Crohn’s disease is perianal fistulizing disease (PFCD). It occurs in up to 50% of the patients who also have symptoms in other parts of the gastrointestinal tract, and in 5% of the cases it occurs as the first manifestation. It is associated with severe symptoms, such as pain, fecal incontinence, and a significant reduction in quality of life. The presence of perianal disease in conjunction with Crohn’s disease portends a significantly worse disease course. These patients require close monitoring to identify those at risk of worsening disease, suboptimal biological drug levels, and signs of developing neoplasm. The last 2 decades have seen significant advancements in the management of PFCD. More recently, newer biologics, cell-based therapies, and novel surgical techniques have been introduced in the hope of improved outcomes. However, in refractory cases, many patients face the decision of having a stoma made and/or a proctectomy performed. In this review, we describe modern surgical management and the most recent advances in the management of complex PFCD, which will likely impact clinical practice.