In Vitro Modeling of Interorgan Crosstalk: Multi-Organ-on-a-Chip for Studying Cardiovascular-Kidney-Metabolic Syndrome

Abstract

Cardiovascular-kidney-metabolic syndrome is a progressive disorder driven by perturbed interorgan crosstalk among adipose, liver, kidney, and heart, leading to multiorgan dysfunction. Capturing the complexity of human cardiovascular-kidney-metabolic syndrome pathophysiology using conventional models has been challenging. Multi-organ-on-a-chip platforms offer a versatile means to study underlying interorgan signaling at different stages of cardiovascular-kidney-metabolic syndrome and bolster clinical translation.

Keywords: cardiovascular diseases; heart failure; inflammation; kidney; metabolic syndrome.

Figure 1.. Cardiovascular-kidney-metabolic (CKM) syndrome staging and pathophysiology.

CKM syndrome stages 0 through 4; clinical definition and prevalence (left). Interorgan crosstalk between the heart, kidney, and metabolic organs propagate CKM syndrome pathology through the exchange of key signaling molecules (depicted outside of the central blood vessel). Further research will help elucidate novel mediators of interorgan communication in CKM syndrome (within the depicted vessel) to guide the development of new therapies.^, ASCVD indicates atherosclerotic cardiovascular disease; CKD, chronic kidney disease; CVD, cardiovascular disease; EVs, extracellular vesicles; FA, fatty acid; IL-6, interluekin-6; MetS, metabolic syndrome; RAAS, renin-angiotensin-aldosterone system; and TNFα, tumor necrosis factor alpha. Figure created with BioRender.com.

Figure 2.. Conceptualization and assembly of single-organ models.

Devices are constructed using a variety of cell sources ranging from primary cells and cell lines to human induced pluripotent stem cell–derived organ progenitors, which are combined in optimized ratios within hydrogels or engineered matrices to form functional tissues. Cells can be matured within the device using mechanical stimulation (eg, through pulsatile flow or cyclic stretch) or electrical pacing. Integrated analytical components, such as microelectrodes, electrochemical sensors, optical sensors, and strain/impedance sensors are used to provide real-time readouts of tissue performance. Platform biofabrication is achieved using diverse techniques such as microfluidics, micropatterning, injection molding, soft lithography, and 3-dimensional (3D) bioprinting. Compartmentalization of cells is accomplished using permeable membranes, with surface topography and nanofabrication techniques used to guide cell alignment. Figure created with BioRender.com.

Figure 3.. Approaches to modeling cardiovascular-kidney-metabolic (CKM) syndrome using a multi-organ-on-a-chip (multi-OoC).

Multi-organ systems incorporating cardiac, kidney, liver, pancreas, and adipose organ modules connected via endothelium-lined microchannels can be used for systems-level modeling of complex interorgan signaling and soluble drug responses in CKM syndrome. Two major strategies for linking multiple multi-OoCs are the combined and the modular chip approaches—in the former, organ modules are developed in parallel in a common ‘blood mimetic’ medium, offering advantages with regard to ease of assembly. For the modular approach, each tissue chip is developed individually and later linked via microchannels with recirculating flow, allowing for incorporation of organ-specific vasculature and tissue features. Multiple organ modules can be obtained via differentiation of patient-specific human induced pluripotent stem cells (hiPSCs). Endothelium-lined vascular channels are fabricated using a porous membrane that allows for exchange of signaling factors, drugs, and their metabolites; more sophisticated models incorporate continuous or period injection of immune cells. Pumps, mechanical actuators, and electrical field stimulation can be used for systemic or modular exposure to physiological stimuli, with tissue-specific readouts quantified using various sensors. Evolving responses can be evaluated using functional assays, immunohistochemical analysis, transcriptomics/proteomics, and cytokine profiling. ECM indicates extracellular matrix. Figure created with BioRender.com.

Figure 4.. Establishing a multi-organ-on-a-chip (multi-OoC) model of stage 2 cardiovascular-kidney-metabolic (CKM) syndrome.

(1) Individual OoCs for heart, kidney, liver, and adipose are assembled. (2) Adipose and liver dysfunction are induced by pathological inflammation while cardiac and renal tissues are cultured in normal medium. (3) All tissues are linked into a multi-OoC and further stimulated with MetS factors (3.1) or normal medium (3.2). (4) Each tissue module can be analyzed using on-chip or off-chip approaches to decipher the impact of metabolic tissue dysfunction on the multi-OoC system. Omics analysis will reveal key signaling pathways involved. EV indicates extracellular vesicles; FFA, free fatty acid; MetS, metabolic syndrome; and RAAS, renin-angiotension-aldosterone system. Figure created with BioRender.com.

Figure 5.. Emerging challenges in multi-organ-on-a-chip (multi-OoC) development.

Substantial hurdles include optimization of organ modules via incorporation of cellular heterogeneity and tissue vascularization, microfabricating appropriately scaled designs that recreate complex, physiologically relevant stimulation patterns, achieving platform integration and high-throughput screening using automation, and ensuring clinical relevance through benchmarking and in silico models. 3D indicates 3-dimensional; and PDMS, polydimethylsiloxane. Figure created with BioRender.com.