Adaptable and hemodynamic Gut-On-VascularNet models to mitigate radiation injury

About This Grant

Acute radiation syndrome (ARS) is a multi-organ failure (MOF) syndrome, resulting from accidental exposure to irradiation and/or nuclear terrorism. Acute and delayed effects of acute radiation exposure (DEARE) can also be seen in the clinic after radiotherapy. While there are FDA-approved drugs for mitigating hematopoietic ARS (H-ARS), there are no treatment for repairing irradiated intestines, primary cause of death and a critical component of gastrointestinal ARS (GI-ARS). A common feature of radiation injury is damage to the microvascular capillary endothelial cells (ECs) that are not only organotypically programmed to modulate metabolism but also provide tissue-specific angiocrine growth factors that orchestrate intestinal repair and regeneration post-radiation. Indeed, intestinal-specific microvascular ECs (InSECs), defined by the expression of transcription factor NKX2-3, establish instructive vascular niches that are essential for maintenance, repair and regeneration of intestinal stem cells (ISC) of irradiated intestines. We show that InSECs choreograph the polarization of the monocytes into reparative IL1beta macrophages that could play a key role in resolving radiation injury. The objective of this proposal is to leverage reproducible in vitro extra-corporeal perfusable vascularized intestinal organoids models to test approaches to restore normal homeostatic functions of InSEC. Thus, we hypothesize that radiation impairs NKX2-3+ InSEC-derived instructive signals and retards recruitment and programming of intestinotropic macrophages that convey reparative signals for intestinal repair. Restoration of NKX2-3 transcriptional signatures in InSECs would reconstitute angiocrine and intestinotropic macrophage functions, essential for resolution and recovery after radiation injury. Delivery of pro-reparative factors such as amphiregulins and epiregulins supplied by macrophages and InSECs could mitigate radiation-inflicted intestinal injury. These hypotheses will be tested through executing the following specific aims: Aim 1: Develop and characterize GI-ARS injury models in human Gut-On-VascularNet organoid extracorporeal platform. Aim 2: To characterize the “instructive” angiocrine signaling pathways of InSEC on pro-regenerative monocytic polarization that mitigate radiation injury to HIOs. Aim 3: To screen for intestinotrophic radiation MCMs to mitigate GI-ARS by using the Gut-On-VascularNet platform. To this end, Rafii and Guha groups plan to capitalize on an engineered scalable near-physiological and reproducible extra- corporeal human Gut-on-VascularNet platform to study radiation injury in GI-ARS. Leveraging this platform, also allows for examining the role of radiation in perfusable microfluidic devices harboring NKX2-3+ InSECs vascularized intestinal organoids to screen for angiocrine factors and reparative macrophages to mitigate GI- ARS. The human Gut-On-VascularNet platform would bridge the gap between animal models and humans for the approval of radiation countermeasures for mitigation of GI-ARS under the FDA “animal rule” guidance.