Abstract Fibrosis occurs in many chronic diseases with lymphatic vascular insufficiency (e.g., kidney disease, tumors, and lymphedema). New lymphatic capillary growth can be triggered by fibrosis‐related tissue stiffening and soluble factors, but questions remain for how related biomechanical, biophysical, and biochemical cues affect lymphatic vascular growth and function. The current preclinical standard for studying lymphatics is animal modeling, but in vitro and in vivo outcomes often do not align. In vitro models can also be limited in their ability to separate vascular growth and function as individual outcomes, and fibrosis is not traditionally included in model design. Tissue engineering provides an opportunity to address in vitro limitations and mimic microenvironmental features that impact lymphatic vasculature. This review discusses fibrosis‐related lymphatic vascular growth and function in disease and the current state of in vitro lymphatic vascular models while highlighting relevant knowledge gaps. Additional insights into the future of in vitro lymphatic vascular models demonstrate how prioritizing fibrosis alongside lymphatics will help capture the complexity and dynamics of lymphatics in disease. Overall, this review aims to emphasize that an advanced understanding of lymphatics within a fibrotic disease—enabled through more accurate preclinical modeling—will significantly impact therapeutic development toward restoring lymphatic vessel growth and function in patients.
more »
« less
Application of microscale culture technologies for studying lymphatic vessel biology
Abstract Immense progress in microscale engineering technologies has significantly expanded the capabilities of in vitro cell culture systems for reconstituting physiological microenvironments that are mediated by biomolecular gradients, fluid transport, and mechanical forces. Here, we examine the innovative approaches based on microfabricated vessels for studying lymphatic biology. To help understand the necessary design requirements for microfluidic models, we first summarize lymphatic vessel structure and function. Next, we provide an overview of the molecular and biomechanical mediators of lymphatic vessel function. Then we discuss the past achievements and new opportunities for microfluidic culture models to a broad range of applications pertaining to lymphatic vessel physiology. We emphasize the unique attributes of microfluidic systems that enable the recapitulation of multiple physicochemical cues in vitro for studying lymphatic pathophysiology. Current challenges and future outlooks of microscale technology for studying lymphatics are also discussed. Collectively, we make the assertion that further progress in the development of microscale models will continue to enrich our mechanistic understanding of lymphatic biology and physiology to help realize the promise of the lymphatic vasculature as a therapeutic target for a broad spectrum of diseases.
more »
« less
- Award ID(s):
- 1752106
- PAR ID:
- 10459742
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Microcirculation
- Volume:
- 26
- Issue:
- 8
- ISSN:
- 1073-9688
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
null (Ed.)To understand how the microvasculature grows and remodels, researchers require reproducible systems that emulate the function of living tissue. Innovative contributions toward fulfilling this important need have been made by engineered microvessels assembled in vitro using microfabrication techniques. Microfabricated vessels, commonly referred to as "vessels on a chip," are from a class of cell culture technologies that uniquely integrate microscale flow phenomena, tissue-level biomolecular transport, cell-cell interactions, and proper 3-D extracellular matrix environments under well-defined culture conditions. Here, we discuss the enabling attributes of microfabricated vessels that make these models more physiological compared to established cell culture techniques, and the potential of these models for advancing microvascular research. This review highlights the key features of microvascular transport and physiology, critically discusses the strengths and limitations of different microfabrication strategies for studying the microvasculature, and provides a perspective on current challenges and future opportunities for vessel on a chip models.more » « less
-
Impaired lymphatic drainage and lymphedema are major morbidities whose mechanisms have remained obscure. To study lymphatic drainage and its impairment, we engineered a microfluidic culture model of lymphatic vessels draining interstitial fluid. This lymphatic drainage-on-chip revealed that inflammatory cytokines that are known to disrupt blood vessel junctions instead tightened lymphatic cell–cell junctions and impeded lymphatic drainage. This opposing response was further demonstrated when inhibition of rho-associated protein kinase (ROCK) was found to normalize fluid drainage under cytokine challenge by simultaneously loosening lymphatic junctions and tightening blood vessel junctions. Studies also revealed a previously undescribed shift in ROCK isoforms in lymphatic endothelial cells, wherein a ROCK2/junctional adhesion molecule-A (JAM-A) complex emerges that is responsible for the cytokine-induced lymphatic junction zippering. To validate these in vitro findings, we further demonstrated in a genetic mouse model that lymphatic-specific knockout of ROCK2 reversed lymphedema in vivo. These studies provide a unique platform to generate interstitial fluid pressure and measure the drainage of interstitial fluid into lymphatics and reveal a previously unappreciated ROCK2-mediated mechanism in regulating lymphatic drainage.more » « less
-
The gut–brain axis (GBA) connects the gastrointestinal tract and the central nervous system (CNS) via the peripheral nervous system and humoral (e.g., circulatory and lymphatic system) routes. The GBA comprises a sophisticated interaction between various mammalian cells, gut microbiota, and systemic factors. This interaction shapes homeostatic and pathophysiological processes and plays an important role in the etiology of many disorders including neuropsychiatric conditions. However, studying the underlying processes of GBA in vivo, where numerous confounding factors exist, is challenging. Furthermore, conventional in vitro models fall short of capturing the GBA anatomy and physiology. Microfluidic platforms with integrated sensors and actuators are uniquely positioned to enhance in vitro models by representing the anatomical layout of cells and allowing to monitor and modulate the biological processes with high spatiotemporal resolution. Here, we first briefly describe microfluidic technologies and their utility in modeling the CNS, vagus nerve, gut epithelial barrier, blood–brain barrier, and their interactions. We then discuss the challenges and opportunities for each model, including the use of induced pluripotent stem cells and incorporation of sensors and actuator modalities to enhance the capabilities of these models. We conclude by envisioning research directions that can help in making the microfluidics-based GBA models better-suited to provide mechanistic insight into pathophysiological processes and screening therapeutics.more » « less
-
The role of the circulatory system, containing the blood and lymphatic vasculatures, within the body, has become increasingly focused on by researchers as dysfunction of either of the systems has been linked to serious complications and disease. Currently, in vivo models are unable to provide the sufficient monitoring and level of manipulation needed to characterize the fluidic dynamics of the microcirculation in blood and lymphatic vessels; thus in vitro models have been pursued as an alternative model. Microfluidic devices have the required properties to provide a physiologically relevant circulatory system model for research as well as the experimental tools to conduct more advanced research analyses of microcirculation flow. In this review paper, the physiological behavior of fluid flow and electrical communication within the endothelial cells of the systems are detailed and discussed to highlight their complexities. Cell co-culturing methods and other relevant organ-on-a-chip devices will be evaluated to demonstrate the feasibility and relevance of the in vitro microfluidic model. Microfluidic systems will be determined as a noteworthy model that can display physiologically relevant flow of the cardiovascular and lymphatic systems, which will enable researchers to investigate the systems' prevalence in diseases and identify potential therapeutics.more » « less
An official website of the United States government
