scholarly journals Can UVA-light-activated riboflavin-induced collagen crosslinking be transferred from ophthalmology to spine surgery? A feasibility study on bovine intervertebral disc

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252672
Author(s):  
Ioannis Vasilikos ◽  
Graciosa Q. Teixeira ◽  
Andreas Seitz ◽  
Julia Nothelfer ◽  
Julian Haas ◽  
...  

Background Collagen cross-links contribute to the mechanical resilience of the intervertebral disc (IVD). UVA-light-activated riboflavin-induced collagen crosslinking (UVA-CXL) is a well-established and effective ophthalmological intervention that increases the mechanical rigidity of the collagen-rich corneal matrix in Keratoconus. This study explores the feasibility, safety and efficacy of translating this intervention in reinforcing the IVD. Methods Annulus fibrosus (AF) cells were isolated from bovine IVDs and treated with different combinations of riboflavin (RF) concentrations (0.05–8 mM) and UVA light intensities (0.3–4 mW/cm2). Metabolic activity (resazurin assay), cell viability (TUNEL assay), and gene expression of apoptosis regulators C-FOS and PT5 were assessed immediately and 24 hours after treatment. Biomechanical effects of UVA-CXL on IVDs were measured by indentation analysis of changes in the instantaneous modulus and by peel-force delamination strength analysis of the AF prior and after treatment. Results Different intensities of UVA did not impair the metabolic activity of AF cells. However, RF affected metabolic activity (p < 0.001). PT53 expression was similar in all RF conditions tested while C-FOS expression decreased 24 hours after treatment. Twenty-four hours after treatment, no apoptotic cells were observed in any condition tested. Biomechanical characterizations showed a significant increase in the annular peel strength of the UVA-CXL group, when compared to controls of UVA and RF alone (p < 0.05). UVA-CXL treated IVDs showed up to 152% higher (p < 0.001) instantaneous modulus values compared to the untreated control. Conclusion This is the first study on UVA-CXL treatment of IVD. It induced significantly increased delamination strength and instantaneous modulus indentation values in intact IVD samples in a structure–function relationship. RF concentrations and UVA intensities utilized in ophthalmological clinical protocols were well tolerated by the AF cells. Our findings suggest that UVA-CXL may be a promising tool to reinforce the IVD matrix.

2021 ◽  
Vol 11 (15) ◽  
pp. 7144
Author(s):  
Muriel C. Bischof ◽  
Sonja Häckel ◽  
Andrea Oberli ◽  
Andreas S. Croft ◽  
Katharina A. C. Oswald ◽  
...  

Increasing evidence implicates intervertebral disc (IVD) degeneration as a major contributor to low back pain. In addition to a series of pathogenic processes, degenerated IVDs become vascularized in contrast to healthy IVDs. In this context, angiopoietin (Ang) plays a crucial role and is involved in cytokine recruitment, and anabolic and catabolic reactions within the extracellular matrix (ECM). Over the last decade, a progenitor cell population has been described in the nucleus pulposus (NP) of the IVD to be positive for the Tie2 marker (also known as Ang-1 receptor). In this study, we investigated the influence of Ang-1 and Ang-2 on human NP cell (Tie2+, Tie2- or mixed) populations isolated from trauma patients during 7 days in normoxia (21% O2) or hypoxia (≤ 5% O2). At the end of the process, the proliferation and metabolic activity of the NP cells were analyzed. Additionally, the relative gene expression of NP-related markers was evaluated. NP cells showed a higher proliferation depending on the Ang treatment. Moreover, the study revealed higher NP cell metabolism when cultured in hypoxia. Additionally, the relative gene expression followed, with an increase linked to the oxygen level and Ang concentration. Our study comparing different NP cell populations may be the start of new approaches for the treatment of IVD degeneration.


1994 ◽  
Vol 1 (3) ◽  
pp. 185-190 ◽  
Author(s):  
Hemlata K. Pokharna ◽  
Betty Boja ◽  
Vincent Monnier ◽  
Roland W. Moskowitz

Author(s):  
А.А. Московцев ◽  
Д.М. Зайченко ◽  
В.Н. Хабаров ◽  
Н.П. Михайлова ◽  
Д.Ю. Тявин ◽  
...  

Гетерополисахарид гиалуронан, являясь ключевым компонентом внеклеточного матрикса, играет важную роль в поддержании определенных физико-химических условий в тканях. Кроме того, гиалуронан может модулировать состояние клеток через взаимодействие с рецепторами и эндоцитоз, однако, эти эффекты недостаточно изучены. Благодаря своим уникальным свойствам, гиалуронан нашел широкое применение в разных областях биомедицины, в частности, активно используется в качестве микроимплантатов в дерму для коррекции возрастных изменений кожи. Вместе с тем, нативный гиалуронан нестабилен при инъекции и подвергается быстрой деградации в ткани, что существенно ограничивает продолжительность вызываемых им эффектов. В данной работе исследуется новая композиция на основе гиалуронана - HR-2, которую отличают ковалентные сшивки между цепями, введенные путем разработанной авторами одностадийной технологии твердофазной модификации полисахаридов. Сшивки препятствуют быстрой деградации гиалуронана. Авторами предложена концепция функционирования гиалуронана в ткани в качестве депо протеиногенных аминокислот и витаминов в целях поддержания биосинтетической активности клеток. Ранее было показано, что сшитый по данной технологии гиалуронан более стабилен в дерме, в связи с чем его действие в качестве депо может быть пролонгировано. В данной работе исследуется влияние на эндотелиоцитоподобные клетки и фибробласты препарата HR-2, представляющего собой новую композицию гиалуроната натрия и сополимера гиалуроновой кислоты с аскорбилфосфатом магния с добавлением глицина, пролина, лизина. В работе проводится сравнение с немодифицированным гиалуронатом натрия. Установлено, что композиция HR-2 в сравнительно высоких концентрациях дозозависимо увеличивает активность дегидрогеназ в фибробластах, что может свидетельствовать о метаболическом их стимулировании. Это отличает препарат HR-2 от нативной гиалуроновой кислоты, ингибирующей в этих же концентрациях метаболическую активность фибробластов. Оба препарата - и HR-2, и нативная гиалуроновая кислота - в малых концентрациях вызывают гормезис-подобный, стимулирующий метаболизм эндотелиоцитов эффект. Цитотоксичность композиции HR-2 ниже нативной гиалуроновой кислоты на обоих клеточных типах. Следует также отметить, что не выявлено достоверного пролиферативного действия обоих препаратов. Полученные в работе новые сведения могут быть использованы для оптимизации режимов применения препаратов гиалуроновой кислоты в биомедицине, с целью достижения максимального терапевтического эффекта и снижения нежелательных последствий его применения. Hyaluronan (HA) is a linear heteropolysaccharide, a key component of the extracellular matrix. It plays an important role in maintaining certain physicochemical conditions in tissues. In addition, hyaluronan can modulate the state of cells through interaction with receptors and endocytosis; however, these effects are not well understood. Due to its unique properties, hyaluronan is widely used in various fields of biomedicine, in particular, as microimplant for correction of age-related skin changes. However, native hyaluronan is unstable when injected and undergoes rapid degradation in the tissue, which significantly limits duration of its effects. In this study, we evaluated a new hyaluronan-based composition, HR-2, which is distinguished by covalent cross-links between the chains. Those cross-links were incorporated using a one-stage technology of solid-phase modification of polysaccharides developed by the authors. The cross-links prevent the rapid degradation of hyaluronan. The authors proposed a concept of injecting hyaluronan into tissue as a depot of proteinogenic amino acids and vitamins in order to maintain the biosynthetic activity of cells. Previously it was shown that hyaluronan produced with this technology was more stable in the dermis, and, therefore, its performance as a depot can be prolonged. In this work, we studied the effect on endotheliocyte-like cells and fibroblasts of HR-2, which is a new composition of sodium hyaluronate and a copolymer of hyaluronic acid with magnesium ascorbyl phosphate supplemented with glycine, proline, and lysine. The study compared HR-2 with unmodified sodium hyaluronate. We found that the composition of HR-2 in relatively high concentrations dose-dependently increased dehydrogenase activities in fibroblasts, that might indicate their metabolic stimulation. This differs HR-2 from native hyaluronic acid, which inhibits the metabolic activity of fibroblasts when added in similar concentrations. Low concentrations of both drugs, HR-2 and native hyaluronic acid, exerted a hormesis-like effect on endotheliocyte metabolism. Cytotoxicity of the HR-2 formulation was lower than of native hyaluronic acid in both cell types. It should also be noted that no reliable proliferative effects of both drugs have been identified. The new information obtained in this study can help optimizing the use of hyaluronic acid drugs in biomedicine to achieve the best therapeutic effect and reduce undesirable consequences of its use.


1994 ◽  
Vol 344 ◽  
Author(s):  
D. Raghavan ◽  
K. Tratt ◽  
R. P. Wool

AbstractDisposal of 200 million waste tires in the US each year has become a major problem. An environmentally sound innovative technology of recycling rubber in cement matrix was examined. Using silane coupling agent the rubber was bonded to the hydrating cement making a lighter composite, which absorbed more energy than ordinary Portland cement. The bonding information was obtained by peel strength analysis. SEM was used to understand the mode of fracture in pure cement paste, cement bonded rubber composite and rubber filled cement paste. It was found that cracks propagate through the rubber particle in rubber bonded cement composite while in unbonded rubber cement mix, the cracks propagate around the interface. The density and shrinkage measurements are also discussed.


2012 ◽  
Vol 7 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Murugesan Vanathi ◽  
Ravi Bypareddy ◽  
Anita Panda

2007 ◽  
Vol 35 (5) ◽  
pp. 853-856 ◽  
Author(s):  
D. Susic

Fibrillar proteins, such as collagens type I and III, and elastin are components of the extracellular matrix. They form an intricate widespread network that provides a basis for maintaining the physical structure of the heart and vessels and also play an important role in determining cardiovascular function. Physiologically, collagen and elastin fibres are enzymatically cross-linked to form matrix. In addition to these enzymatically formed cross-links, collagen fibres may be linked non-enzymatically, most notably by formation of AGEs (advanced glycation end-products). AGEs are formed by a reaction between reducing sugars and body proteins; they are formed increasingly in diabetes mellitus and hypertension and they accumulate with aging. There are several mechanisms whereby AGEs may affect cardiovascular structure and function. These include increased myocardial and vascular stiffness and (upon reaction with their receptors) inflammatory reactions, release of growth factors and cytokines, and increased oxidative stress. Therefore breaking AGEs appears as a promising tool in the therapy of cardiovascular injury related to diabetes, hypertension and aging. Breakers of AGE cross-links have been developed and one of them, alagebrium, has been extensively studied. This brief review discusses the formation of AGEs, their role in mediating cardiovascular injury, as well as the results of experimental and clinical studies involving alagebrium.


Antibiotics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 53 ◽  
Author(s):  
Michael R Hamblin ◽  
Heidi Abrahamse

Since the early work of the 1900s it has been axiomatic that photodynamic action requires the presence of sufficient ambient oxygen. The Type I photochemical pathway involves electron transfer reactions leading to the production of reactive oxygen species (superoxide, hydrogen peroxide, and hydroxyl radicals), while the Type II pathway involves energy transfer from the PS (photosensitizer) triplet state, leading to production of reactive singlet oxygen. The purpose of the present review is to highlight the possibility of oxygen-independent photoinactivation leading to the killing of pathogenic bacteria, which may be termed the “Type III photochemical pathway”. Psoralens can be photoactivated by ultraviolet A (UVA) light to produce DNA monoadducts and inter-strand cross-links that kill bacteria and may actually be more effective in the absence of oxygen. Tetracyclines can function as light-activated antibiotics, working by a mixture of oxygen-dependent and oxygen independent pathways. Again, covalent adducts may be formed in bacterial ribosomes. Antimicrobial photodynamic inactivation can be potentiated by addition of several different inorganic salts, and in the case of potassium iodide and sodium azide, bacterial killing can be achieved in the absence of oxygen. The proposed mechanism involves photoinduced electron transfer that produces reactive inorganic radicals. These new approaches might be useful to treat anaerobic infections or infections in hypoxic tissue.


2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Marine Hovakimyan ◽  
Rudolf F. Guthoff ◽  
Oliver Stachs

Collagen cross-linking (CXL) using UVA light and riboflavin (vitamin B2) was introduced as a clinical application to stabilize the cornea by inducing cross-links within and between collagen fibers. CXL has been investigated extensively and has been shown clinically to arrest the progression of keratoconic or post-LASIK ectasia. With its minimal cost, simplicity, and proven positive clinical outcome, CXL can be regarded as a useful approach to reduce the number of penetrating keratoplasties performed. Small case series have also indicated that CXL is beneficial in corneal edema by reducing stromal swelling behavior and in keratitis by inhibiting pathogen growth. Despite these encouraging results, CXL remains a relatively new method that is potentially associated with complications. Aspects such as side effects and recurrence rates have still to be elucidated. In light of the growing interest in CXL, our paper summarizes present knowledge about this promising approach. We have intentionally endeavored to include the more relevant studies from the recent literature to provide an overview of the current status of CXL.


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