Which Design and Biomaterial Factors Affect Clinical Wear Performance of Total Disc Replacements? A Systematic Review

Background Total disc replacement was clinically introduced to reduce pain and preserve segmental motion of the lumbar and cervical spine. Previous case studies have reported on the wear and adverse local tissue reactions around artificial prostheses, but it is unclear how design and biomaterials affect clinical outcomes. Questions/purposes Which design and material factors are associated with differences in clinical wear performance (implant wear and periprosthetic tissue response) of (1) lumbar and (2) cervical total disc replacements? Methods We performed a systematic review on the topics of implant wear and periprosthetic tissue response using an advanced search in MEDLINE and Scopus electronic databases. Of the 340 references identified, 33 were retrieved for full-text evaluation, from which 16 papers met the inclusion criteria (12 on lumbar disc replacement and five on cervical disc replacement; one of the included studies reported on both lumbar and cervical disc replacement), which involved semiquantitative analysis of wear and adverse local tissue reactions along with a description of the device used. An additional three papers were located by searching bibliographies of key articles. There were seven case reports, three case series, two case-control studies, and seven analytical studies. The Methodological Index for Non-randomized Studies (MINORS) Scale was used to score case series and case-control studies, which yielded mean scores of 10.3 of 16 and 17.5 of 24, respectively. In general, the case series (three) and case-control (two) studies were of good quality. Results In lumbar regions, metal-on-polymer devices with mobile-bearing designs consistently generated small and large polymeric wear debris, triggering periprosthetic tissue activation of macrophages and giant cells, respectively. In the cervical regions, metal-on-polymer devices with fixed-bearing designs had similar outcomes. All metal-on-metal constructs tended to generate small metallic wear debris, which typically triggered an adaptive immune response of predominantly activated lymphocytes. There were no retrieval studies on one-piece prostheses. Conclusions This review provides evidence that design and biomaterials affect the type of wear and inflammation. However, clinical study design, followup, and analytical techniques differ among investigations, preventing us from drawing firm conclusions about the relationship between implant design and wear performance for both cervical and lumbar total disc replacement

Chemical modification of extracellular matrix by cold atmospheric plasma-generated reactive species affects chondrogenesis and bone formation.

The goal of this study was to investigate whether cold plasma generated by dielectric barrier discharge (DBD) modifies extracellular matrices (ECM) to influence chondrogenesis and endochondral ossification. Replacement of cartilage by bone during endochondral ossification is essential in fetal skeletal development, bone growth and fracture healing. Regulation of this process by the ECM occurs through matrix remodelling, involving a variety of cell attachment molecules and growth factors, which influence cell morphology and protein expression. The commercially available ECM, Matrigel, was treated with microsecond or nanosecond pulsed (μsp or nsp, respectively) DBD frequencies conditions at the equivalent frequencies (1 kHz) or power (~1 W). Recombinant human bone morphogenetic protein-2 was added and the mixture subcutaneously injected into mice to simulate ectopic endochondral ossification. Two weeks later, the masses were extracted and analysed by microcomputed tomography. A significant increase in bone formation was observed in Matrigel treated with μsp DBD compared with control, while a significant decrease in bone formation was observed for both nsp treatments. Histological and immunohistochemical analysis showed Matrigel treated with μsp plasma increased the number of invading cells, the amount of vascular endothelial growth factor and chondrogenesis while the opposite was true for Matrigel treated with nsp plasma. In support of the in vivo Matrigel study, 10 T1/2 cells cultured in vitro on μsp DBD-treated type I collagen showed increased expression of adhesion proteins and activation of survival pathways, which decreased with nsp plasma treatments. These results indicate DBD modification of ECM can influence cellular behaviours to accelerate or inhibit chondrogenesis and endochondral ossification. Copyright © 2016 John Wiley & Sons, Ltd

Reactive oxygen and nitrogen species induce protein and DNA modifications driving arthrofibrosis following total knee arthroplasty

BACKGROUND: Arthrofibrosis, occurring in 3%-4% of patients following total knee arthroplasty (TKA), is a challenging condition for which there is no defined cause. The hypothesis for this study was that disregulated production of reactive oxygen species (ROS) and nitrogen species (RNS) mediates matrix protein and DNA modifications, which result in excessive fibroblastic proliferation. RESULTS: We found increased numbers of macrophages and lymphocytes, along with elevated amounts of myeloperoxidase (MPO) in arthrofibrotic tissues when compared to control tissues. MPO expression, an enzyme that generates ROS/RNS, is usually limited to neutrophils and some macrophages, but was found by immunohistochemistry to be expressed in both macrophages and fibroblasts in arthrofibrotic tissue. As direct measurement of ROS/RNS is not feasible, products including DNA hydroxylation (8-OHdG), and protein nitrosylation (nitrotyrosine) were measured by immunohistochemistry. Quantification of the staining showed that 8-OHdg was significantly increased in arthrofibrotic tissue. There was also a direct correlation between the intensity of inflammation and ROS/RNS to the amount of heterotopic ossification (HO). In order to investigate the aberrant expression of MPO, a real-time oxidative stress polymerase chain reaction array was performed on fibroblasts isolated from arthrofibrotic and control tissues. The results of this array confirmed the upregulation of MPO expression in arthrofibrotic fibroblasts and highlighted the downregulated expression of the antioxidants, superoxide dismutase1 and microsomal glutathione S-transferase 3, as well as the significant increase in thioredoxin reductase, a known promoter of cell proliferation, and polynucleotide kinase 3\u27-phosphatase, a key enzyme in the base excision repair pathway for oxidative DNA damage. CONCLUSION: Based on our current findings, we suggest that ROS/RNS initiate and sustain the arthrofibrotic response driving aggressive fibroblast proliferation and subsequent HO

Mast cells and hypoxia drive tissue metaplasia and heterotopic ossification in idiopathic arthrofibrosis after total knee arthroplasty

ABSTRACT: BACKGROUND: Idiopathic arthrofibrosis occurs in 3-4% of patients who undergo total knee arthroplasty (TKA). However, little is known about the cellular or molecular changes involved in the onset or progression of this condition. To classify the histomorphologic changes and evaluate potential contributing factors, periarticular tissues from the knees of patients with arthrofibrosis were analyzed for fibroblast and mast cell proliferation, heterotopic ossification, cellular apoptosis, hypoxia and oxidative stress. RESULTS: The arthrofibrotic tissue was composed of dense fibroblastic regions, with limited vascularity along the outer edges. Within the fibrotic regions, elevated numbers of chymase/fibroblast growth factor (FGF)-expressing mast cells were observed. In addition, this region contained fibrocartilage and associated heterotopic ossification, which quantitatively correlated with decreased range of motion (stiffness). Fibrotic, fibrocartilage and ossified regions contained few terminal dUTP nick end labeling (TUNEL)-positive or apoptotic cells, despite positive immunostaining for lactate dehydrogenase (LDH)5, a marker of hypoxia, and nitrotyrosine, a marker for protein nitrosylation. LDH5 and nitrotyrosine were found in the same tissue areas, indicating that hypoxic areas within the tissue were associated with increased production of reactive oxygen and nitrogen species. CONCLUSIONS: Taken together, we suggest that hypoxia-associated oxidative stress initiates mast cell proliferation and FGF secretion, spurring fibroblast proliferation and tissue fibrosis. Fibroblasts within this hypoxic environment undergo metaplastic transformation to fibrocartilage, followed by heterotopic ossification, resulting in increased joint stiffness. Thus, hypoxia and associated oxidative stress are potential therapeutic targets for fibrosis and metaplastic progression of idiopathic arthrofibrosis after TKA

Nonthermal atmospheric pressure plasma enhances mouse limb bud survival, growth, and elongation.

The enhanced differentiation of mesenchymal cells into chondrocytes or osteoblasts is of paramount importance in tissue engineering and regenerative therapies. A newly emerging body of evidence demonstrates that appendage regeneration is dependent on reactive oxygen species (ROS) production and signaling. Thus, we hypothesized that mesenchymal cell stimulation by nonthermal (NT)-plasma, which produces and induces ROS, would (1) promote skeletal cell differentiation and (2) limb autopod development. Stimulation with a single treatment of NT-plasma enhanced survival, growth, and elongation of mouse limb autopods in an in vitro organ culture system. Noticeable changes included enhanced development of digit length and definition of digit separation. These changes were coordinated with enhanced Wnt signaling in the distal apical epidermal ridge (AER) and presumptive joint regions. Autopod development continued to advance for approximately 144 h in culture, seemingly overcoming the negative culture environment usually observed in this in vitro system. Real-time quantitative polymerase chain reaction analysis confirmed the up-regulation of chondrogenic transcripts. Mechanistically, NT-plasma increased the number of ROS positive cells in the dorsal epithelium, mesenchyme, and the distal tip of each phalange behind the AER, determined using dihydrorhodamine. The importance of ROS production/signaling during development was further demonstrated by the stunting of digital outgrowth when anti-oxidants were applied. Results of this study show NT-plasma initiated and amplified ROS intracellular signaling to enhance development of the autopod. Parallels between development and regeneration suggest that the potential use of NT-plasma could extend to both tissue engineering and clinical applications to enhance fracture healing, trauma repair, and bone fusion

Inhibition of apoptosis signal-regulating kinase 1 alters the wound epidermis and enhances auricular cartilage regeneration.

Why regeneration does not occur in mammals remains elusive. In lower vertebrates, epimorphic regeneration of the limb is directed by the wound epidermis, which controls blastema formation to promote regrowth of the appendage. Herein, we report that knockout (KO) or inhibition of Apoptosis Signal-regulated Kinase-1 (ASK1), also known as mitogen-activated protein kinase kinase kinase 5 (MAP3K5), after full thickness ear punch in mice prolongs keratinocyte activation within the wound epidermis and promotes regeneration of auricular cartilage. Histological analysis showed the ASK1 KO ears displayed enhanced protein markers associated with blastema formation, hole closure and regeneration of auricular cartilage. At seven days after punch, the wound epidermis morphology was markedly different in the KO, showing a thickened stratum corneum with rounded cell morphology and a reduction of both the granular cell layer and decreased expression of filament aggregating protein. In addition, cytokeratin 6 was expressed in the stratum spinosum and granulosum. Topical application of inhibitors of ASK1 (NQDI-1), the upstream ASK1 activator, calcium activated mitogen kinase 2 (KN93), or the downstream target, c-Jun N-terminal kinase (SP600125) also resulted in enhanced regeneration; whereas inhibition of the other downstream target, the p38 α/β isoforms, (SB203580) had no effect. The results of this investigation indicate ASK1 inhibition prolongs keratinocyte and blastemal cell activation leading to ear regeneration

Skeletal cell differentiation is enhanced by atmospheric dielectric barrier discharge plasma treatment.

Enhancing chondrogenic and osteogenic differentiation is of paramount importance in providing effective regenerative therapies and improving the rate of fracture healing. This study investigated the potential of non-thermal atmospheric dielectric barrier discharge plasma (NT-plasma) to enhance chondrocyte and osteoblast proliferation and differentiation. Although the exact mechanism by which NT-plasma interacts with cells is undefined, it is known that during treatment the atmosphere is ionized generating extracellular reactive oxygen and nitrogen species (ROS and RNS) and an electric field. Appropriate NT-plasma conditions were determined using lactate-dehydrogenase release, flow cytometric live/dead assay, flow cytometric cell cycle analysis, and Western blots to evaluate DNA damage and mitochondrial integrity. We observed that specific NT-plasma conditions were required to prevent cell death, and that loss of pre-osteoblastic cell viability was dependent on intracellular ROS and RNS production. To further investigate the involvement of intracellular ROS, fluorescent intracellular dyes Mitosox (superoxide) and dihydrorhodamine (peroxide) were used to assess onset and duration after NT-plasma treatment. Both intracellular superoxide and peroxide were found to increase immediately post NT-plasma treatment. These increases were sustained for one hour but returned to control levels by 24 hr. Using the same treatment conditions, osteogenic differentiation by NT-plasma was assessed and compared to peroxide or osteogenic media containing β-glycerolphosphate. Although both NT-plasma and peroxide induced differentiation-specific gene expression, neither was as effective as the osteogenic media. However, treatment of cells with NT-plasma after 24 hr in osteogenic or chondrogenic media significantly enhanced differentiation as compared to differentiation media alone. The results of this study show that NT-plasma can selectively initiate and amplify ROS signaling to enhance differentiation, and suggest this technology could be used to enhance bone fusion and improve healing after skeletal injury

Protein markers indicating cellular activities of blastema formation were more prevalent in the ASK1 KO.

<p>A) Sections were stained for H2AX immunofluorescence, positive green nuclear fluorescent dots (white arrows) were consistently observed in the ASK1 KO tissue. The percentage of H2AX-positive cells was determined by counting all the positive cells per total cells in blastemal area in 3 fields from 3 mice. Data are presented as mean ± SEM. B) Similar DAB immunohistochemistry was performed with antibodies to p21 and MMP-13 positively stained cells are shown at black arrows in high magnification inset. Percent of positive stained cells/ total cells was determined and graphed for WT, HET, and ASK1 KO mice. White scale bar = 100 μm, black scale bar = 500 μm in low mag image and 100 μm in high mag. inset.</p