BMSCs-Derived Exosomes Ameliorate Pain Via Abrogation of Aberrant Nerve Invasion in Subchondral Bone in Lumbar Facet Joint Osteoarthritis.

Lumbar facet joint osteoarthritis (LFJ OA) is regarded as one of the common causes of low back pain (LBP). The pathogenesis and underlying mechanism of this disease are largely unknown, there is still no effective disease-modifying therapy. This study aims to investigate the efficacy of exosomes derived from bone marrow mesenchymal stem cells (BMSCs) on the pathogenesis and behavioral signs of LBP in the LFJ OA mouse model. The pathogenetic change in cartilage and aberrant nerve invasion in the subchondral bone of LFJ in a mouse model after treatment with BMSC-exosomes was evaluated. BMSC-exosomes could relieve pain via abrogation of aberrant CGRP-positive nerve and abnormal H-type vessel formation in the subchondral bone of LFJ. Moreover, BMSC-exosomes attenuated cartilage degeneration and inhibited tartrate-resistant acid phosphatase expression and RANKL-RANK-TRAF6 signaling activation to facilitate subchondral bone remodeling. These results indicated that BMSC-exosomes could relive behavioral signs of LBP and pathological processes in LFJ OA. BMSC-exosomes have a prominent protective effect and might be a potential therapeutic option for the treatment of LFJ OA causing LBP. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:670-679, 2020.

Acetabular labrum of hip joint in osteoarthritis: A qualitative original study and short review of the literature.

PURPOSE: Histological architecture of normal acetabular labrum regarding free nerve endings (FNEs) and mechanoreceptors (MRs) has been satisfactorily described in the literature. However, the presence of FNEs and MRs in acetabular labrum of hip joint has been analyzed only once in patients with osteoarthritis (OA). Aim of this article is to report histological distribution pattern of FNEs and MRs in acetabular labrum of patients with severe OA, at the same time conducting a comparison with normal acetabular labrum described in the literature. METHODS: Seven patients with severe hip OA were enrolled in this study. Patient selection was assisted by the utilization of specific clinical scales delineated by the American College of Rheumatology. After successful total hip arthroplasty, tissue samples of acetabular labra of seven patients were histologically processed and stained with the gold standard chloride method, which was subsequently examined under a compound microscope. RESULTS: FNEs and MRs constituted the major histological structures. Identified MRs included Pacini corpuscles, Ruffini corpuscles, and Golgi-Mazzoni corpuscles. The presence of FNEs was predominant in the middle part of the acetabular labrum, featuring a remarkable decrease in peripheral parts. In contrast, MRs were detected basically in peripheral parts and less in the middle part. CONCLUSIONS: Differentiation of the distribution pattern of MRs and FNEs in acetabular labrum of hip joint is remarkable between normal patients and patients with severe OA. The abundance of FNEs in the middle part of the pathologic labrum is mainly responsible for the observed discrimination. A "conversion" of MRs to FNEs may occur during OA progression, modulating therefore this pattern as well as the upcoming clinical manifestations.

Arthroscopic patelloplasty and circumpatellar denervation for the treatment of patellofemoral osteoarthritis.

BACKGROUND: Patellofemoral osteoarthritis commonly occurs in older people, often resulting in anterior knee pain and severely reduced quality of life. The aim was to examine the effectiveness of arthroscopic patelloplasty and circumpatellar denervation for the treatment of patellofemoral osteoarthritis (PFOA). METHODS: A total of 156 PFOA patients (62 males, 94 females; ages 45-81 years, mean 66 years) treated in our department between September 2012 and March 2013 were involved in this study. Clinical manifestations included recurrent swelling and pain in the knee joint and aggravated pain upon ascending/descending stairs, squatting down, or standing up. PFOA was treated with arthroscopic patelloplasty and circumpatellar denervation. The therapeutic effects before and after surgery were statistically evaluated using Lysholm and Kujala scores. The therapeutic effects were graded by classification of the degree of cartilage defect. RESULTS: A total of 149 cases were successfully followed up for 14.8 months, on average. The incisions healed well, and no complications occurred. After surgery, the average Lysholm score improved from 73.29 to 80.93, and the average Kujala score improved from 68.34 to 76.48. This procedure was highly effective for patients with cartilage defects I-III but not for patients with cartilage defect IV. CONCLUSIONS: For PFOA patients, this procedure is effective for significantly relieving anterior knee pain, improving knee joint function and quality of life, and deferring arthritic progression.

Neurovascular invasion at the osteochondral junction and in osteophytes in osteoarthritis.

BACKGROUND: Normal adult articular cartilage is thought to be avascular and aneural. OBJECTIVE: To describe neurovascular structures at the osteochondral junction and in osteophytes in tibiofemoral osteoarthritis (OA) displaying a range of severity of cartilage changes. METHODS: Articular surfaces were obtained from 40 patients at total knee joint replacement surgery for tibiofemoral OA (TKR) and seven patients post mortem (PM). Antibodies directed against CD34 (vascular endothelium), protein gene product 9.5 (pan-neuronal marker), substance P and calcitonin gene-related peptide (sensory nerves) and C-flanking peptide of neuropeptide Y (sympathetic nerves) were used to localise blood vessels and nerves by immunohistochemistry. Severity of OA cartilage changes was graded histologically. RESULTS: TKR and PM samples displayed a range of OA cartilage changes including tidemark breaching by vascular channels. Sympathetic and sensory nerves were both present within vascular channels in the articular cartilage, in both mild and severe OA. Perivascular and free nerve fibres, and nerve trunks were observed within the subchondral bone marrow and within the marrow cavities of osteophytes. Sensory and sympathetic nerves displayed similar distributions in each region studied. CONCLUSION: Vascularisation and the associated innervation of articular cartilage may contribute to tibiofemoral pain in OA across a wide range of structural disease severity.

Mechanoreceptors and nerve endings of the triangular fibrocartilage in the human wrist.

PURPOSE: To increase our understanding of the mechanism of pain and the sensation of wrist instability by studying the distribution of the mechanoreceptors in the triangular fibrocartilage (TFC). METHODS: The distribution and density of the nerve endings were investigated in 34 TFC specimens obtained from human cadavers. We studied the dorsal, palmar, ulnar, radial, and central areas after staining by a modified gold chloride technique. RESULTS: The free nerve endings, responsible for sensing pain, predominate in the ulnar and dorsal areas. The Vater-Pacini corpuscles predominate in the radial and dorsal area, promoting perception of the onset or cessation of movement and mechanical stress change. The Golgi-Mazzoni corpuscles were more frequent in the ulnar and ventral areas, linking these areas to function of slow adaptation and sensation of extreme movements. The proprioceptive function receptors were found in all areas of TFC because Ruffini corpuscles have homogeneous distribution in this fibrocartilaginous tissue. CONCLUSIONS: Our results showed that the nerve endings were distributed at the periphery of TFC and showed different concentrations of each type of mechanoreceptors per topographic area, suggesting that they play specific roles in the proprioceptive and nociceptive reflexes of the wrist.

The innervation of the triangular fibrocartilage complex: nitric acid maceration rediscovered.

Injury to the triangular fibrocartilage complex (TFCC) is frequently implicated in the etiology of ulnar-sided wrist pain. This study examines the nervous anatomy of the TFCC using a nitric acid maceration technique and attempts to correlate this information with known tear patterns. Ten fresh frozen cadaveric specimens were studied in detail. Gross dissection of each upper-extremity specimen included removal of all flexor and extensor tendons. After identification and labeling with permanent color of the ulnar nerve, dorsal sensory branch of the ulnar nerve, posterior interosseous nerve, anterior interosseous nerve, and median nerve, an en bloc excision of the distal radioulnar region was performed. Digestion of the soft tissue was performed with nitric acid at sequential concentrations of 50% and 33% for 9 of 10 specimens. The digestion was halted by immersing the specimen in a mixture of 10% formaldehyde and 1% glycerine. After removal of bone, the specimens were fixed in paraffin, sectioned, and stained with hematoxylin and eosin. Nine of the 10 specimens were studied microscopically to determine the contribution of the grossly identified nerves to each zone of the triangular fibrocartilage complex as defined by Palmer's classification of acute TFCC tears. The anterior interosseous, median, and superficial radial nerves did not contribute to the innervation of the TFCC. The intraarticular course of the peripheral nerves could not be defined in the one specimen that was not digested with nitric acid. Nitric acid maceration is a rediscovered technique for identifying the nervous anatomy of soft tissues. The study showed that the triangular fibrocartilage complex is innervated by branches of the posterior interosseous, ulnar, and dorsal sensory ulnar nerves in a fairly consistent manner. Improved treatment of TFCC tears may result from an enhanced understanding of the supporting structures' innervation and mechanical function.

Retrograde tracing and neuropeptide immunohistochemistry of sensory neurones projecting to the cartilaginous distal femoral epiphysis of young rats.

Although cartilage is considered to be devoid of innervation, axons occur in the perichondrium and during development in cartilage canals, thereby having a relatively close spatial relationship to chondroblasts and chondrocytes. The present study locates the source of the sensory innervation of the femoral cartilaginous epiphyses of young rats and investigates whether the neuropeptide calcitonin gene-related peptide (CGRP) can influence chondrocytes. Retrograde tracing from the distal femoral epiphysis of young rats with Fast Blue (FB) showed labelled neuronal profiles in the L2-L5 dorsal root ganglia. Sample countings indicated that 50% of the FB-labelled neuronal profiles were located at the L3 level and 25% at the L4 level. The labelled neurones had diameters of 15-40 microm, with a peak at 25-30 microm. Immunohistochemistry showed that about 50% of the FB-labelled profiles contained CGRP. Together with the finding that CGRP influences bone cells to generate the second messenger cAMP, this result suggested the hypothesis that chondrocytes might be similarly influenced by CGRP. However, stimulation of cartilage slices with CGRP in vitro followed by an assay of the cAMP content did not provide support for this hypothesis. We conclude that primary sensory neurones containing CGRP project to the perichondrium and to cartilage canals of growing cartilage, and that exogenous CGRP does not elevate the cAMP content of cartilage slices in vitro.

Morphology and distribution of nerve endings in the human triangular fibrocartilage complex.

We studied the morphology and distribution of nerve endings in the human triangular fibrocartilage complex using both silver staining and immunohistochemical staining using a protein specific to nerve fibres. Free nerve endings were found in the ulnar side of the triangular fibrocartilage complex, especially in the ulnar collateral ligament, meniscus homologue and the adjacent collagen fibre area of the peripheral part of the ulnar side of the articular disc. Meissner's and Krause's corpuscles were observed in the ulnar collateral ligament and meniscus homologue. The fact that free nerve endings were observed in the meniscus homologue and adjacent collagen fibre area of the peripheral part of the ulnar side of the articular disc suggests that this disc may be a source of wrist pain. The presence of nerve end bulbs in the triangular fibrocartilage complex also suggests a possible role for corpuscles as mechanoreceptors.

Cell trafficking, mediator release, and articular metabolism in acute inflammation of innervated or denervated isolated equine joints.

OBJECTIVES: To describe the acute cellular response, inflammatory mediator release, and effect on chondrocyte metabolism of interleukin 1 beta (IL-1 beta) in isolated innervated or denervated equine metacarpophalangeal joints. ANIMALS: One metacarpophalangeal joint of 24 adult horses. PROCEDURES: The metacarpophalangeal joint was isolated for 6 hours in a pump-perfused, auto-oxygenated, innervated or denervated metacarpophalangeal joint preparation. Isolated joints were assigned to 4 groups: control, control-denervated, inflamed, and inflamed-denervated, and inflammation was induced by intra-articular injection of IL-1 beta. Synovial fluid was collected for cytologic examination and determination of IL (IL)-1 beta, (IL-6), prostaglandin E2 (PGE2), and substance P (SP) values. Synovial membrane was immunostained with SP and nerve-specific enolase (NSE) antibodies. Cartilage was collected for determination of proteoglycan (PG) synthesis and degradation. RESULTS: IL-1 beta induced significant neutrophilic leukocytosis in synovial and synovial membrane. IL-1 beta concentration and returned to baseline by 5.5 hours, but IL-6 concentration significantly increased throughout the study. Total SP content was significantly higher in inflamed joints. There was a significant increase in 24- and 48-hour PG degradation in inflamed innervated joints. CONCLUSION: Cellular response to IL-1 beta was rapid and sustained; joint clearance of IL-1 beta was rapid, and endogenous production of IL-1 beta did not follow. The IL-6 and PGE2 concentrations significantly increased, and SP content was increased in association with inflammation but not denervation. A degradative response of cartilage of IL-1 beta was observed, and was enhanced by innervation. This model was useful for investigation of the articular response to acute inflammation and the influence of denervation in modulating this response.

Neural anatomy of the glenohumeral ligaments, labrum, and subacromial bursa.

The neural histology of the human shoulder ligaments, glenoid labrum, and subacromial bursae were studied using a modified gold chloride stain. Two morphological types of mechanoreceptors and free nerve endings were found in the ligaments. Slow adapting Ruffini end organs and rapidly adapting Pacinian corpuscles were identified in the superior, middle, inferior, and the posterior glenohumeral ligaments. These specialized proprioceptive nerve endings were also found in the coracoclavicular, and coracoacromial ligaments. Only free nerve endings were found in the glenoid labrum and these were located in the peripheral half. Scattered free nerve endings were found throughout the subacromial bursae. This is the first histological evidence of neural receptors in the human shoulder ligaments, glenoid labrum, and the subacromial bursae. Any disruption of the labrum or these ligaments by trauma or surgery can deprive the shoulder of mechanical stability, and may cause a decrease in proprioception because of the loss of these afferent neural receptors. Removal of symptomatic, inflamed bursae may decrease pain signals from this area of the shoulder.

Changes in the innervation of rabbit craniomandibular joint tissues associated with experimental induction of anterior disk displacement: histochemical and immunohistochemical studies.

We have previously reported that surgical induction of anterior disk displacement (ADD) in a rabbit craniomandibular joint (CMJ) leads to histopathological changes consistent with osteoarthritis. This paper reports the changes that were noted in the innervation of rabbit CMJ tissues following surgical induction of ADD. The right joint of 30 rabbits was exposed surgically and the discal attachments were severed except for the posterior discal attachment (bilaminar zone). The disk was then displaced anteriorly and sutured to the zygomatic arch. The left joints was used as sham-operated control. CMJ tissues were then removed after fixation and processed for histochemical localization of nerve fibers using the silver impregnation technique and immunohistochemical localization of neurofilaments using monoclonal antibodies. The results showed an absence of nerve fibers in the control and experimental disks and their presence in the control and experimental bilaminar zones. The bilaminar zone adhesions to the experimental condyles were also innervated. The spread of nerve fibers into the pathological fibrous adhesions surrounding the arthritic condyles in this animal model of ADD may indicate a possible mechanism of nociception in this disease.

Neural elements in the human temporomandibular articular disc.

The purpose of this study was to determine the presence and describe the location of neural elements in the articular disc of the human temporomandibular joint. Six articular discs were obtained from three adult human subjects at autopsy. Four discs were cut into segments of known anterior-posterior orientation. The remaining two were processed intact. All tissues were stained in bulk with gold chloride, and frozen, sectioned on a sliding microtome at 70 to 100 microns, mounted on slides, dehydrated, and coverslipped. Nerve fibers were seen penetrating the discs from the pericapsular connective tissue. Structures resembling Ruffini endings, Pacinian corpuscles, and Golgi tendon organs were identified in the pericapsular connective tissue and within the disc. The population density of neural elements was the greatest at the periphery of the disc and progressively decreased towards the center, which was essentially devoid of them. The concentration of neural elements appeared to be greater at the anterior and posterior margins of the disc, with the greatest concentration being posteriorly. These findings support the theory that afferent nerves may arise from neural elements within the disc.

Functional anatomy of the temporomandibular joint.

Some of the features of the anatomical structures of the temporomandibular joint are outlined, and a brief account of development and nerve supply is followed by consideration of some of the biomechanical aspects of the muscles of mastication.

Distribution of substance P-like immunoreactive nerve fibers in temporomandibular joint soft tissues of monkey.

The distribution of substance P-immunoreactive and silver impregnated nerve fibers in the temporomandibular joint soft tissues of the Macaca fascicularis monkey was investigated in frozen sections. The pattern of substance P-immunoreactive structures in the soft tissues and periosteum of the temporomandibular joint was compared with the distribution of silver impregnated nerve fibers within these tissues. Presence of substance P-immunoreactive fibers was demonstrated in the temporomandibular joint capsule, disc attachments, fascia, adjacent periosteum and within the interfascicular connective tissue of the lateral pterygoid muscle. The overall distribution corresponded to that of silver impregnated nerve fibers. Substance P-immunoreactive nerve fibers were found in the adventitia of arteries in all vascularized temporomandibular joint soft tissues but could not be found in the adventitia of veins. No substance P-immunoreactive or silver impregnated nerve fibers were seen in the dense collagenous tissue forming the disc. Substance P is suggested to influence the major features of inflammation and to play a role in acute and chronic pain conditions.

The vascular and nerve supply of the human meniscus.

Twenty-three fresh, cadaver knees were studied to evaluate details of the vascular and nerve supply of the menisci in humans. Vascularity was investigated using dye and latex injections, and the nerve supply was studied microscopically using a variety of special stains. Vessels arise mainly from medial and lateral inferior and middle geniculate arteries. Radial branches from a perimeniscal plexus enter the meniscus at intervals, with a richer supply to the anterior and posterior horns. Vessels supplying the body are limited to the peripheral one-third, except in the fetus. There is an avascular area adjacent to the popliteus tendon. The perimeniscal tissue is richly innervated. Most nerves are associated with vessels. Smaller nerves and axons run radially in convoluted patterns. Single axons course through the perimeniscal tissue, and many nerves are seen in the interstitial tissue of the outer one-third of the meniscus and in the anterior and posterior horns. The inner two-thirds has no nerve fibers.