Species variation in the cartilaginous endplate of the lumbar intervertebral disc

Abstract

Backgrounds Cartilaginous endplate (CEP) plays an essential role in intervertebral disc (IVD) health and disease. The aim was to compare the CEP structure of lumbar IVD and to reveal the detailed pattern of integration between the CEP and bony endplate (BEP) from different species. Methods A total of 34 IVDs (5 human, 5 goat, 8 pig, 8 rabbit, and 8 rat IVDs) were collected, fixed and midsagittally cut; in each IVD, one‐half was used for histological staining to observe the CEP morphology, and the other half was used for scanning electron microscopy (SEM) analysis to measure the diameters and distributions of collagen fibers in the central and peripheral CEP areas and to observe the pattern of CEP‐BEP integration from different species. Results The human, pig, goat, and rabbit IVDs had the typical BEP‐CEP structure, but the rat CEP was directly connected with the growth plate. Human CEP was the thickest (896.95 ± 87.71 μm) among these species, followed by pig, goat, rat, and rabbit CEPs. Additionally, the mean cellular density of the rabbit CEP was the highest, which was 930 ± 202 per mm2, followed by the rat, goat, pig, and human CEPs. In all the species, the collagen fiber diameter in the peripheral area was much bigger than that in the central area. The collagen fiber diameters of CEP from the human, pig, goat, and rat were distributed between 35 nm and 65 nm. The BEP and CEP were connected by the collagen from the CEP, aggregating into bundles or cross links with each other to form a network, and anchored to BEP. Conclusions Significant differences in the thickness, cellular density, and collagen characterization of CEPs from different species were demonstrated; the integration of BEP‐CEP in humans, pigs, goats, and rabbits was mainly achieved by the collagen bundles anchoring system, while the typical BEP‐CEP interface did not exist in rats.

Facet joint degeneration—An initial procedure of the cervical spine degeneration

“…The two pain‐related phenotypes have been used as evaluation indicators in cartilage endplate tissue and subchondral bone. 31 , 32 , 33 With tissue damaged, DRG neurons are highly sensitive due to the activation of nociceptors by various neurotransmitters, including SP and CGRP, released by nociceptive nerve fibers, resulting in hyperalgesia. Thus, we detected the ingrowth of SP + and CGRP + sensory never fibers in the subchondral bone of C4/5 FJs and the endplate of IVDs in the same segment.…”

“…It has been reported that nerve ingrowth and secretion of pain‐related factors are two common phenotypes of cervical degeneration. The two pain‐related phenotypes have been used as evaluation indicators in cartilage endplate tissue and subchondral bone 31–33 . With tissue damaged, DRG neurons are highly sensitive due to the activation of nociceptors by various neurotransmitters, including SP and CGRP, released by nociceptive nerve fibers, resulting in hyperalgesia.…”

Homing of vertebral‐delivered mesenchymal stromal cells for degenerative intervertebral discs repair – an in vivo proof‐of‐concept study

“…Specifically, the rat IVD is hallmarked by differences in its dimensions, cell populations (predominantly notochordal cells instead of chondrogenic NP cells), endplate organization, and so forth. 25 , 27 , 57 , 58 , 59 , 60 , 61 Moreover, the model employed involves a more acute disc degeneration model rather than the commonly chronic degenerative processes involved in human discogenic pain. 58 , 62 How these differences might negatively or positively impact the therapeutic potential of a vertebral MSC transplantation strategy remains to be determined.…”

“…Moreover, the translatability of the results in our rat model to a human scenario remains to be confirmed. Specifically, the rat IVD is hallmarked by differences in its dimensions, cell populations (predominantly notochordal cells instead of chondrogenic NP cells), endplate organization, and so forth 25,27,57–61 . Moreover, the model employed involves a more acute disc degeneration model rather than the commonly chronic degenerative processes involved in human discogenic pain 58,62 .…”

Cartilaginous endplates: A comprehensive review on a neglected structure in intervertebral disc research

“…Resist fluid flow in and out of the disc and maintain a uniform stress distribution across the IVD, 86,223,224 and prevent the disc from herniating or bulging 9,223,224 Distribute load during joint movement and provide lubricated (low friction) movement 37 Withstand compressive loads to the IVD and maintain the BEP-CEP interface through fluid pressure 1 Confine the NP laterally, 7 and anchor for the IVD to the VB. 48…”