The Effect of the Repression of Oxidative Stress on Tenocyte Differentiation: A Preliminary Study of a Rat Cell Model Using a Novel Differential Tensile Strain Bioreactor

Abstract

Because of limitations in the current understanding of the exact pathogenesis of tendinopathy, and the lack of an optimal experimental model, effective therapy for the disease is currently unavailable. This study aims to prove that repression of oxidative stress modulates the differentiation of tendon-derived cells (TDCs) sustaining excessive tensile strains, and proposes a novel bioreactor capable of applying differential tensile strains to cultured cells simultaneously. TDCs, including tendon-derived stem cells, tenoblasts, tenocytes, and fibroblasts, were isolated from the patellar tendons of Sprague‒Dawley rats. Cyclic uniaxial stretching with 4% or 8% strain at 0.5 Hz for 8 h was applied to TDCs. TDCs subjected to 8% strain were treated with epigallocatechin gallate (EGCG), piracetam, or no medication. Genes representing non-tenocyte lineage (Pparg, Sox9, and Runx2) and type I and type III collagen were analyzed by quantitative polymerase chain reaction. The 8% strain group showed increased expression of non-tenocyte lineage genes and type III/type I collagen ratios compared with the control and 4% strain groups, and the increased expression was ameliorated with addition of EGCG and piracetam. The model developed in this work could be applied to future research on the pathophysiology of tendinopathy and development of treatment options for the disease. Repression of oxidative stress diminishes the expression of genes indicating aberrant differentiation in a rat cell model, which indicates potential therapeutic intervention of tendinopathy, the often relentlessly degenerate condition.

Antioxidant effect of nicotinamide mononucleotide in tendinopathy

“…Using an in vivo collagenase-induced tendinopathy model developed in 2019 by Hsiao et al [ 34 ], the present study demonstrates that NMN administration downregulated NOX1 and NOX4 expression, while enhancing SIRT1 levels and SOD activation, resulting in decreased oxidative stress. Accordingly, the in vivo results confirmed the findings observed in vitro.…”

“…Microinjuries associated with overload and repetitive mechanical stimulation induce excessive production of ROS in tendon cells [ 10 , 31 ]. Oxidative stress was shown to inhibit tendon healing in a tendinopathy rat model in vivo [ 33 ], as well as block tenocyte differentiation in vitro [ 34 ]. Furthermore, continuous oxidative stress has been reported to induce apoptotic death in tenocytes through the activation of caspase-3 [ 35 ].…”

Roles of Oxidative Stress in Acute Tendon Injury and Degenerative Tendinopathy—A Target for Intervention

“…The gene expression of non-tenocyte markers after treatment with HA hydrogel and EGCG-loaded HA hydrogel was reduced, but the differences were not statistically significant. However, in another study, the supplementation with antioxidants, EGCG and piracetam, respectively, significantly suppressed the mRNA expression of non-tenocyte markers and type III collagen/type I collagen ratio in intensively loaded tendon cells [ 108 ]. In animals, a single injection of EGCG-loaded hydrogel one day after collagenase injection improved the histological score compared to the saline injection group at day 14 post-injury in the collagenase-induced Achilles tendinopathy model.…”

“…In animals, a single injection of EGCG-loaded hydrogel one day after collagenase injection improved the histological score compared to the saline injection group at day 14 post-injury in the collagenase-induced Achilles tendinopathy model. The mRNA expression of type III collagen/type I collagen ratio decreased, and the mRNA expression of non-tenocyte markers decreased in the tendon in both the HA hydrogel group and the EGCG-loaded HA hydrogel group, but the differences were statistically significant only for the expression of the type III collagen/type I collagen ratio in both groups and PPARg (an adipogenic marker) in the EGCG-loaded HA hydrogel group [ 108 ].…”

A universal multi-platform 3D printed bioreactor chamber for tendon tissue engineering

“…Researchers use either custom-made tensile bioreactors or commercially available systems such as the EBERS TC-3 and the CellScale MC series. Our search of literature published between January 2016 and April 2020 indicates that of 24 published studies on cyclic loading in tendon tissue engineering, three groups published data generated using a CellScale bioreactor 25 , 28 , 34 and one group published using an EBERS TC-3 bioreactor, 41 with the remaining 20 using custom-designed bioreactors 19 – 24 , 26 , 27 , 29 – 33 , 35 – 40 , 42 , 43 (summarised in Table 1 ). There is a clear requirement for greater reproducibility and consistency in the methodological approach to enable both comparative research and translation towards effective clinical therapies.…”