Engineering sensory ganglion multicellular system to model tissue nerve ingrowth

Abstract

Discogenic pain is associated with deep nerve ingrowth in annulus fibrosus tissue (AF) of intervertebral disc (IVD). To model AF nerve ingrowth, primary bovine dorsal root ganglion (DRG) micro-scale tissue units are spatially organized around an AF explant by mild hydrodynamic forces within a collagen matrix. This results in a densely packed multicellular system mimicking the native DRG tissue morphology and a controlled AF-neuron distance. Such a multicellular organization is essential to evolve populational-level cellular functions and in vivo-like morphologies. Pro-inflammatory cytokine-primed AF demonstrates its neurotrophic and neurotropic effects on nociceptor axons. Both effects depend on the AF-neuron distance underpinning the role of recapitulating inter-tissue/organ anatomical proximity when investigating their crosstalk. This is the first in vitro model studying AF nerve ingrowth by engineering mature and large animal tissues in a morphologically and physiologically relevant environment. Our new approach can be used to biofabricate multi-tissue/organ models for untangling pathophysiological conditions and develop novel therapies.

Sound-Based Assembly of Three-Dimensional Cellularized and Acellularized Constructs

“…Sound-based assembly aims to increase the local particulates density at a nearly physiological level through a very mild process that does not harms cells. [24,25] In the present case, sound-based assembly clusters within the "on-target" region (i.e., the anulus within 3.5-4.5 mm from the center) nearly the 60-70% of the total particles while the remaining 30-40% of the total spheroids are angularly evenly distributed at longer distances from the center. This remarks a key difference with the extrusion based bioprinting technologies where 100% of the used particulate system is "on-target" since it is directly deposited by the dispensed hydrogel-based ink.…”

“…[22,23] Interestingly, this phenomenon can be originated in liquids which can be later jellified so that the obtained particles condensate can be fixed by polymerizing the liquid solution and used on demand. [20] This sound-based assembly has been used by several researchers to investigate blood vessels formation, [24] nerve ingrowths in low back pain in vitro model, [25] for tumor in vitro model, [26] to recreate 3D in vitro cardiac tissue, [27] to assemble milli-scale cellu-robots, [28] and more recently to fabricate hepatic lobules. [29] Nevertheless sound-based assembly J o u r n a l P r e -p r o o f demonstrate its superior ability in creating cell condensates, the cell constructs are restricted to a 2.5D dimension because of the underlying physics.…”

Sound-based assembly of three-dimensional cellularized and acellularized constructs

“…Yet, we highlight once more, that this technology is based on an essentially different principles in respect to the conventional bioprinting technologies where the particulate systems are dispensed or preferentially ‘encaged’ in specific positions. Sound-based assembly aims to increase the local particulates density at a nearly physiological level through a very mild process that does not harms cells [ 24 , 25 ]. In the present case, sound-based assembly clusters within the “on-target” region ( i.e., the anulus within 3.5–4.5 mm from the center) nearly the 60–70% of the total particles while the remaining 30–40% of the total spheroids are angularly evenly distributed at longer distances from the center.…”

“…Interestingly, this phenomenon can be originated in liquids which can be later jellified so that the obtained particles condensate can be fixed by polymerizing the liquid solution and used on demand [ 20 ]. This sound-based assembly has been used by several researchers to investigate blood vessels formation [ 24 ], nerve ingrowths in low back pain in vitro model [ 25 ], for tumor in vitro model [ 26 ], to recreate 3D in vitro cardiac tissue [ 27 ], to assemble milli-scale cellu-robots [ 28 ], and more recently to fabricate hepatic lobules [ 29 ]. Nevertheless sound-based assembly demonstrate its superior ability in creating cell condensates, the cell constructs are restricted to a 2.5D dimension because of the underlying physics.…”